Contact Dermatitis

Consider popular nutritional supplements as a potential source of allergic reactions if the cause of the reaction is otherwise unknown, Alison Ehrlich, MD, said at the annual meeting of the American Contact Dermatitis Society.

Sherri Holdridge

Allergens may be hidden in a range of supplement products, from colorings in vitamin C powders to some vitamins used in hair products and other products.

“In general, our patients do not tell us what supplements they are taking,” said Dr. Ehrlich, a dermatologist who practices in Washington, D.C. Antiaging, sleep, and weight loss/weight control supplements are among the most popular, she said.

Surveys have shown that many patients do not discuss supplement use with their health care providers, in part because they believe their providers would disapprove of supplement use, and patients are not educated about supplements, she said. “This is definitely an area that we should try to learn more about,” she added.

Current regulations regarding dietary supplements stem from the Dietary Supplement Health and Education Act of 1994, which defined dietary supplements as distinct from meals but regulated them as a category of food, not as medications. Dietary supplements can be vitamins, minerals, herbs, and extracts, Dr. Ehrlich said.

“There is not a lot of safety wrapped around how supplements come onto the market,” she explained. “It is not the manufacturer’s responsibility to test these products and make sure they are safe. When they get pulled off the market, it is because safety reports are getting back to the FDA.”

Consequently, a detailed history of supplement use is important, as it may reveal possible allergens as the cause of previously unidentified reactions, she said.

Dr. Ehrlich shared a case involving a patient who claimed to have had a reaction to a “Prevage-like” product that was labeled as a crepe repair cream. Listed among the product’s ingredients was idebenone, a synthetic version of the popular antioxidant known as Coenzyme Q.
 

Be wary of vitamins

Another potential source of allergy is vitamin C supplements, which became especially popular during the pandemic as people sought additional immune system support, Dr. Ehrlich noted. “What kind of vitamin C product our patients are taking is important,” she said. For example, some vitamin C powders contain coloring agents, such as carmine. Some also contain gelatin, which may cause an allergic reaction in individuals with alpha-gal syndrome, she added.

Sally Koch Kubetin/MDedge News

In general, water-soluble vitamins such as vitamins B1 to B9, B12, and C are more likely to cause an immediate reaction, Dr. Ehrlich said. Fat-soluble vitamins, such as vitamins A, D, E, and K, are more likely to cause a delayed reaction of allergic contact dermatitis.

Dr. Ehrlich described some unusual reactions to vitamins that have been reported, including a systemic allergy associated with vitamin B1 (thiamine), burning mouth syndrome associated with vitamin B3 (nicotinate), contact urticaria associated with vitamin B5 (panthenol), systemic allergy and generalized ACD associated with vitamin E (tocopherol), and erythema multiforme–like ACD associated with vitamin K1.

Notably, vitamin B5 has been associated with ACD as an ingredient in hair products, moisturizers, and wound care products, as well as B-complex vitamins and fortified foods, Dr. Ehrlich said.

Herbs and spices can act as allergens as well. Turmeric is a spice that has become a popular supplement ingredient, she said. Turmeric and curcumin (found in turmeric) can be used as a dye for its yellow color as well as a flavoring but has been associated with allergic reactions. Another popular herbal supplement, ginkgo biloba, has been marketed as a product that improves memory and cognition. It is available in pill form and in herbal teas.

“It’s really important to think about what herbal products our patients are taking, and not just in pill form,” Dr. Ehrlich said. “We need to expand our thoughts on what the herbs are in.”
 

Consider food additives as allergens

Food additives, in the form of colorants, preservatives, or flavoring agents, can cause allergic reactions, Dr. Ehrlich noted.

The question of whether food-additive contact sensitivity has a role in the occurrence of atopic dermatitis (AD) in children remains unclear, she said. However, a study published in 2020 found that 62% of children with AD had positive patch test reactions to at least one food-additive allergen, compared with 20% of children without AD. The additives responsible for the most reactions were azorubine (24.4%); formic acid (15.6%); and carmine, cochineal red, and amaranth (13.3% for each).

Common colorant culprits in allergic reactions include carmine, annatto, tartrazine, and spices (such as paprika and saffron), Dr. Ehrlich said. Carmine is used in meat to prevent photo-oxidation and to preserve a red color, and it has other uses as well, she said. Carmine has been associated with ACD, AD flares, and immediate hypersensitivity. Annatto is used in foods, including processed foods, butter, and cheese, to provide a yellow color. It is also found in some lipsticks and has been associated with urticaria and angioedema, she noted.

Food preservatives that have been associated with allergic reactions include butylated hydroxyanisole and sulfites, Dr. Ehrlich said. Sulfites are used to prevent food from turning brown, and it may be present in dried fruit, fruit juice, molasses, pickled foods, vinegar, and wine.

Reports of ACD in response to sodium metabisulfite have been increasing, she noted. Other sulfite reactions may occur with exposure to other products, such as cosmetics, body washes, and swimming pool water, she said.

Awareness of allergens in supplements is important “because the number of our patients taking supplements for different reasons is increasing” and allergens in supplements could account for flares, Dr. Ehrlich said. Clinicians should encourage patients to tell them what supplements they use. Clinicians should review the ingredients in these supplements with their patients to identify potential allergens that may be causing reactions, she advised.

Dr. Ehrlich has disclosed no relevant financial relationships.

A version of this article first appeared on Medscape.com.

Consider popular nutritional supplements as a potential source of allergic reactions if the cause of the reaction is otherwise unknown, Alison Ehrlich, MD, said at the annual meeting of the American Contact Dermatitis Society.

Sherri Holdridge

Allergens may be hidden in a range of supplement products, from colorings in vitamin C powders to some vitamins used in hair products and other products.

“In general, our patients do not tell us what supplements they are taking,” said Dr. Ehrlich, a dermatologist who practices in Washington, D.C. Antiaging, sleep, and weight loss/weight control supplements are among the most popular, she said.

Surveys have shown that many patients do not discuss supplement use with their health care providers, in part because they believe their providers would disapprove of supplement use, and patients are not educated about supplements, she said. “This is definitely an area that we should try to learn more about,” she added.

Current regulations regarding dietary supplements stem from the Dietary Supplement Health and Education Act of 1994, which defined dietary supplements as distinct from meals but regulated them as a category of food, not as medications. Dietary supplements can be vitamins, minerals, herbs, and extracts, Dr. Ehrlich said.

“There is not a lot of safety wrapped around how supplements come onto the market,” she explained. “It is not the manufacturer’s responsibility to test these products and make sure they are safe. When they get pulled off the market, it is because safety reports are getting back to the FDA.”

Consequently, a detailed history of supplement use is important, as it may reveal possible allergens as the cause of previously unidentified reactions, she said.

Dr. Ehrlich shared a case involving a patient who claimed to have had a reaction to a “Prevage-like” product that was labeled as a crepe repair cream. Listed among the product’s ingredients was idebenone, a synthetic version of the popular antioxidant known as Coenzyme Q.
 

Be wary of vitamins

Another potential source of allergy is vitamin C supplements, which became especially popular during the pandemic as people sought additional immune system support, Dr. Ehrlich noted. “What kind of vitamin C product our patients are taking is important,” she said. For example, some vitamin C powders contain coloring agents, such as carmine. Some also contain gelatin, which may cause an allergic reaction in individuals with alpha-gal syndrome, she added.

Sally Koch Kubetin/MDedge News

In general, water-soluble vitamins such as vitamins B1 to B9, B12, and C are more likely to cause an immediate reaction, Dr. Ehrlich said. Fat-soluble vitamins, such as vitamins A, D, E, and K, are more likely to cause a delayed reaction of allergic contact dermatitis.

Dr. Ehrlich described some unusual reactions to vitamins that have been reported, including a systemic allergy associated with vitamin B1 (thiamine), burning mouth syndrome associated with vitamin B3 (nicotinate), contact urticaria associated with vitamin B5 (panthenol), systemic allergy and generalized ACD associated with vitamin E (tocopherol), and erythema multiforme–like ACD associated with vitamin K1.

Notably, vitamin B5 has been associated with ACD as an ingredient in hair products, moisturizers, and wound care products, as well as B-complex vitamins and fortified foods, Dr. Ehrlich said.

Herbs and spices can act as allergens as well. Turmeric is a spice that has become a popular supplement ingredient, she said. Turmeric and curcumin (found in turmeric) can be used as a dye for its yellow color as well as a flavoring but has been associated with allergic reactions. Another popular herbal supplement, ginkgo biloba, has been marketed as a product that improves memory and cognition. It is available in pill form and in herbal teas.

“It’s really important to think about what herbal products our patients are taking, and not just in pill form,” Dr. Ehrlich said. “We need to expand our thoughts on what the herbs are in.”
 

Consider food additives as allergens

Food additives, in the form of colorants, preservatives, or flavoring agents, can cause allergic reactions, Dr. Ehrlich noted.

The question of whether food-additive contact sensitivity has a role in the occurrence of atopic dermatitis (AD) in children remains unclear, she said. However, a study published in 2020 found that 62% of children with AD had positive patch test reactions to at least one food-additive allergen, compared with 20% of children without AD. The additives responsible for the most reactions were azorubine (24.4%); formic acid (15.6%); and carmine, cochineal red, and amaranth (13.3% for each).

Common colorant culprits in allergic reactions include carmine, annatto, tartrazine, and spices (such as paprika and saffron), Dr. Ehrlich said. Carmine is used in meat to prevent photo-oxidation and to preserve a red color, and it has other uses as well, she said. Carmine has been associated with ACD, AD flares, and immediate hypersensitivity. Annatto is used in foods, including processed foods, butter, and cheese, to provide a yellow color. It is also found in some lipsticks and has been associated with urticaria and angioedema, she noted.

Food preservatives that have been associated with allergic reactions include butylated hydroxyanisole and sulfites, Dr. Ehrlich said. Sulfites are used to prevent food from turning brown, and it may be present in dried fruit, fruit juice, molasses, pickled foods, vinegar, and wine.

Reports of ACD in response to sodium metabisulfite have been increasing, she noted. Other sulfite reactions may occur with exposure to other products, such as cosmetics, body washes, and swimming pool water, she said.

Awareness of allergens in supplements is important “because the number of our patients taking supplements for different reasons is increasing” and allergens in supplements could account for flares, Dr. Ehrlich said. Clinicians should encourage patients to tell them what supplements they use. Clinicians should review the ingredients in these supplements with their patients to identify potential allergens that may be causing reactions, she advised.

Dr. Ehrlich has disclosed no relevant financial relationships.

A version of this article first appeared on Medscape.com.

Consider popular nutritional supplements as a potential source of allergic reactions if the cause of the reaction is otherwise unknown, Alison Ehrlich, MD, said at the annual meeting of the American Contact Dermatitis Society.

Sherri Holdridge

Allergens may be hidden in a range of supplement products, from colorings in vitamin C powders to some vitamins used in hair products and other products.

“In general, our patients do not tell us what supplements they are taking,” said Dr. Ehrlich, a dermatologist who practices in Washington, D.C. Antiaging, sleep, and weight loss/weight control supplements are among the most popular, she said.

Surveys have shown that many patients do not discuss supplement use with their health care providers, in part because they believe their providers would disapprove of supplement use, and patients are not educated about supplements, she said. “This is definitely an area that we should try to learn more about,” she added.

Current regulations regarding dietary supplements stem from the Dietary Supplement Health and Education Act of 1994, which defined dietary supplements as distinct from meals but regulated them as a category of food, not as medications. Dietary supplements can be vitamins, minerals, herbs, and extracts, Dr. Ehrlich said.

“There is not a lot of safety wrapped around how supplements come onto the market,” she explained. “It is not the manufacturer’s responsibility to test these products and make sure they are safe. When they get pulled off the market, it is because safety reports are getting back to the FDA.”

Consequently, a detailed history of supplement use is important, as it may reveal possible allergens as the cause of previously unidentified reactions, she said.

Dr. Ehrlich shared a case involving a patient who claimed to have had a reaction to a “Prevage-like” product that was labeled as a crepe repair cream. Listed among the product’s ingredients was idebenone, a synthetic version of the popular antioxidant known as Coenzyme Q.
 

Be wary of vitamins

Another potential source of allergy is vitamin C supplements, which became especially popular during the pandemic as people sought additional immune system support, Dr. Ehrlich noted. “What kind of vitamin C product our patients are taking is important,” she said. For example, some vitamin C powders contain coloring agents, such as carmine. Some also contain gelatin, which may cause an allergic reaction in individuals with alpha-gal syndrome, she added.

Sally Koch Kubetin/MDedge News

In general, water-soluble vitamins such as vitamins B1 to B9, B12, and C are more likely to cause an immediate reaction, Dr. Ehrlich said. Fat-soluble vitamins, such as vitamins A, D, E, and K, are more likely to cause a delayed reaction of allergic contact dermatitis.

Dr. Ehrlich described some unusual reactions to vitamins that have been reported, including a systemic allergy associated with vitamin B1 (thiamine), burning mouth syndrome associated with vitamin B3 (nicotinate), contact urticaria associated with vitamin B5 (panthenol), systemic allergy and generalized ACD associated with vitamin E (tocopherol), and erythema multiforme–like ACD associated with vitamin K1.

Notably, vitamin B5 has been associated with ACD as an ingredient in hair products, moisturizers, and wound care products, as well as B-complex vitamins and fortified foods, Dr. Ehrlich said.

Herbs and spices can act as allergens as well. Turmeric is a spice that has become a popular supplement ingredient, she said. Turmeric and curcumin (found in turmeric) can be used as a dye for its yellow color as well as a flavoring but has been associated with allergic reactions. Another popular herbal supplement, ginkgo biloba, has been marketed as a product that improves memory and cognition. It is available in pill form and in herbal teas.

“It’s really important to think about what herbal products our patients are taking, and not just in pill form,” Dr. Ehrlich said. “We need to expand our thoughts on what the herbs are in.”
 

Consider food additives as allergens

Food additives, in the form of colorants, preservatives, or flavoring agents, can cause allergic reactions, Dr. Ehrlich noted.

The question of whether food-additive contact sensitivity has a role in the occurrence of atopic dermatitis (AD) in children remains unclear, she said. However, a study published in 2020 found that 62% of children with AD had positive patch test reactions to at least one food-additive allergen, compared with 20% of children without AD. The additives responsible for the most reactions were azorubine (24.4%); formic acid (15.6%); and carmine, cochineal red, and amaranth (13.3% for each).

Common colorant culprits in allergic reactions include carmine, annatto, tartrazine, and spices (such as paprika and saffron), Dr. Ehrlich said. Carmine is used in meat to prevent photo-oxidation and to preserve a red color, and it has other uses as well, she said. Carmine has been associated with ACD, AD flares, and immediate hypersensitivity. Annatto is used in foods, including processed foods, butter, and cheese, to provide a yellow color. It is also found in some lipsticks and has been associated with urticaria and angioedema, she noted.

Food preservatives that have been associated with allergic reactions include butylated hydroxyanisole and sulfites, Dr. Ehrlich said. Sulfites are used to prevent food from turning brown, and it may be present in dried fruit, fruit juice, molasses, pickled foods, vinegar, and wine.

Reports of ACD in response to sodium metabisulfite have been increasing, she noted. Other sulfite reactions may occur with exposure to other products, such as cosmetics, body washes, and swimming pool water, she said.

Awareness of allergens in supplements is important “because the number of our patients taking supplements for different reasons is increasing” and allergens in supplements could account for flares, Dr. Ehrlich said. Clinicians should encourage patients to tell them what supplements they use. Clinicians should review the ingredients in these supplements with their patients to identify potential allergens that may be causing reactions, she advised.

Dr. Ehrlich has disclosed no relevant financial relationships.

A version of this article first appeared on Medscape.com.

Cutaneous Manifestations

Capsicum peppers are used worldwide in preparing spicy dishes. Their active ingredient—capsaicin—is used as a topical medicine to treat localized pain. Capsicum peppers can cause irritant contact dermatitis with symptoms of erythema, cutaneous burning, and itch.¹

Irritant contact dermatitis is a common occupational skin disorder. Many cooks have experienced the sting of a chili pepper after contact with the hands or eyes. Cases of chronic exposure to Capsicum peppers with persistent burning and pain have been called Hunan hand syndrome.² Capsicum peppers also have induced allergic contact dermatitis in a food production worker.³

Capsicum peppers also are used in pepper spray, tear gas, and animal repellents because of their stinging properties. These agents usually cause cutaneous tingling and burning that soon resolves; however, a review of 31 studies showed that crowd-control methods with Capsicum-containing tear gas and pepper spray can cause moderate to severe skin damage such as a persistent skin rash or erythema, or even first-, second-, or third-degree burns.⁴

Topical application of capsaicin isolate is meant to cause burning and deplete local neuropeptides, with a cutaneous reaction that ranges from mild to intolerable.^5,6 Capsaicin also is found in other products. In one published case report, a 3-year-old boy broke out in facial urticaria when his mother kissed him on the cheek after she applied lip plumper containing capsaicin to her lips.⁷ Dermatologists should consider capsaicin an active ingredient that can irritate the skin in the garden, in the kitchen, and in topical products.

Obtaining Relief

Capsaicin-induced dermatitis can be relieved by washing the area with soap, detergent, baking soda, or oily compounds that act as solvents for the nonpolar capsaicin.⁸ Application of ice water or a high-potency topical steroid also may help. If the reaction is severe and persistent, a continuous stellate ganglion block may alleviate the pain of capsaicin-induced contact dermatitis.⁹

Identifying Features and Plant Facts

The Capsicum genus includes chili peppers, paprika, and red peppers. Capsicum peppers are native to tropical regions of the Americas (Figure). The use of Capsicum peppers in food can be traced to Indigenous peoples of Mexico as early as 7000 bc.¹⁰ On the Scoville scale, which was developed to quantify the hotness of foods and spices, Capsicum peppers are rated at approximately 2 million units; by comparison, jalapeño peppers have a Scoville score of 4500¹¹ and capsaicin isolate has a score of 16 million units. Capsicum species rank among the hottest peppers in the world.

Capsicum belongs to the family Solanaceae, which includes tobacco, tomatoes, potatoes, and nightshade plants. There are many varieties of peppers in the Capsicum genus, with 5 domesticated species: Capsicum annuum, Capsicum baccatum, Capsicum chinense, Capsicum frutescens, and Capsicum pubescens. These include bell, poblano, cayenne, tabasco, habanero, and ají peppers, among others. Capsicum species grow as a shrub with flowers that rotate to stellate corollas and rounded berries of different sizes and colors.¹² Capsaicin and other alkaloids are concentrated in the fruit; therefore, Capsicum dermatitis is most commonly induced by contact with the flesh of peppers.

 

 

Irritant Chemicals

Capsaicin (8-methyl-6-nonanoyl vanillylamide) is a nonpolar phenol, which is why washing skin that has come in contact with capsaicin with water or vinegar alone is insufficient to solubilize it.¹³ Capsaicin binds to the transient receptor potential vanilloid 1 (TRPV1), a calcium channel on neurons that opens in response to heat. When bound, the channel opens at a lower temperature threshold and depolarizes nerve endings, leading to vasodilation and activation of sensory nerves.¹⁴ Substance P is released and the individual experiences a painful burning sensation. When purified capsaicin is frequently applied at an appropriate dose, synthesis of substance P is diminished, resulting in reduced local pain overall.¹⁵

Capsaicin does not affect neurons without TRPV1, and administration of capsaicin is not painful if given with anesthesia. An inappropriately high dose of capsaicin destroys cells in the epidermal barrier, resulting in water loss and inducing release of vasoactive peptides and inflammatory cytokines.¹ Careful handling of Capsicum peppers and capsaicin products can reduce the risk for irritation.

Medicinal Use

On-/Off-Label and Potential Uses—Capsaicin is US Food and Drug Administration approved for use in arthritis and musculoskeletal pain. It also is used to treat diabetic neuropathy,⁵ postherpetic neuralgia,⁶ psoriasis,¹⁶ and other conditions. Studies have shown that capsaicin might be useful in treating trigeminal neuralgia,¹⁷ fibromyalgia,¹⁸ migraines,¹⁴ cluster headaches,⁹ and HIV-associated distal sensory neuropathy.⁵

Delivery of Capsaicin—Capsaicin preferentially acts on C-fibers, which transmit dull, aching, chronic pain.¹⁹ The compound is available as a cream, lotion, and large bandage (for the lower back), as well as low- and high-dose patches. Capsaicin creams, lotions, and the low-dose patch are uncomfortable and must be applied for 4 to 6 weeks to take effect, which may impact patient adherence. The high-dose patch, which requires administration under local anesthesia by a health care worker, brings pain relief with a single use and improves adherence.¹¹ Synthetic TRPV1-agonist injectables based on capsaicin have undergone clinical trials for localized pain (eg, postoperative musculoskeletal pain); many patients experience pain relief, though benefit fades over weeks to months.^20,21

Use in Traditional Medicine—Capsicum peppers have been used to aid digestion and promote healing in gastrointestinal conditions, such as dyspepsia.²² The peppers are a source of important vitamins and minerals, including vitamins A, C, and E; many of the B complex vitamins; and magnesium, calcium, and iron.²³

Use as Cancer Therapy—Studies of the use of capsaicin in treating cancer have produced controversial results. In cell and animal models, capsaicin induces apoptosis through downregulation of the Bcl-2 protein; upregulation of oxidative stress, tribbles-related protein 3 (TRIB3), and caspase-3; and other pathways.^19,24-26 On the other hand, consumption of Capsicum peppers has been associated with cancer of the stomach and gallbladder.²⁷ Capsaicin might have anticarcinogenic properties, but its mechanism of action varies, depending on variables not fully understood.

Final Thoughts

Capsaicin is a neuropeptide-active compound found in Capsicum peppers that has many promising applications for use. However, dermatologists should be aware of the possibility of a skin reaction to this compound from handling peppers and using topical medicines. Exposure to capsaicin can cause irritant contact dermatitis that may require clinical care.

Cutaneous Manifestations

Capsicum peppers are used worldwide in preparing spicy dishes. Their active ingredient—capsaicin—is used as a topical medicine to treat localized pain. Capsicum peppers can cause irritant contact dermatitis with symptoms of erythema, cutaneous burning, and itch.¹

Irritant contact dermatitis is a common occupational skin disorder. Many cooks have experienced the sting of a chili pepper after contact with the hands or eyes. Cases of chronic exposure to Capsicum peppers with persistent burning and pain have been called Hunan hand syndrome.² Capsicum peppers also have induced allergic contact dermatitis in a food production worker.³

Capsicum peppers also are used in pepper spray, tear gas, and animal repellents because of their stinging properties. These agents usually cause cutaneous tingling and burning that soon resolves; however, a review of 31 studies showed that crowd-control methods with Capsicum-containing tear gas and pepper spray can cause moderate to severe skin damage such as a persistent skin rash or erythema, or even first-, second-, or third-degree burns.⁴

Topical application of capsaicin isolate is meant to cause burning and deplete local neuropeptides, with a cutaneous reaction that ranges from mild to intolerable.^5,6 Capsaicin also is found in other products. In one published case report, a 3-year-old boy broke out in facial urticaria when his mother kissed him on the cheek after she applied lip plumper containing capsaicin to her lips.⁷ Dermatologists should consider capsaicin an active ingredient that can irritate the skin in the garden, in the kitchen, and in topical products.

Obtaining Relief

Capsaicin-induced dermatitis can be relieved by washing the area with soap, detergent, baking soda, or oily compounds that act as solvents for the nonpolar capsaicin.⁸ Application of ice water or a high-potency topical steroid also may help. If the reaction is severe and persistent, a continuous stellate ganglion block may alleviate the pain of capsaicin-induced contact dermatitis.⁹

Identifying Features and Plant Facts

The Capsicum genus includes chili peppers, paprika, and red peppers. Capsicum peppers are native to tropical regions of the Americas (Figure). The use of Capsicum peppers in food can be traced to Indigenous peoples of Mexico as early as 7000 bc.¹⁰ On the Scoville scale, which was developed to quantify the hotness of foods and spices, Capsicum peppers are rated at approximately 2 million units; by comparison, jalapeño peppers have a Scoville score of 4500¹¹ and capsaicin isolate has a score of 16 million units. Capsicum species rank among the hottest peppers in the world.

Capsicum belongs to the family Solanaceae, which includes tobacco, tomatoes, potatoes, and nightshade plants. There are many varieties of peppers in the Capsicum genus, with 5 domesticated species: Capsicum annuum, Capsicum baccatum, Capsicum chinense, Capsicum frutescens, and Capsicum pubescens. These include bell, poblano, cayenne, tabasco, habanero, and ají peppers, among others. Capsicum species grow as a shrub with flowers that rotate to stellate corollas and rounded berries of different sizes and colors.¹² Capsaicin and other alkaloids are concentrated in the fruit; therefore, Capsicum dermatitis is most commonly induced by contact with the flesh of peppers.

 

 

Irritant Chemicals

Capsaicin (8-methyl-6-nonanoyl vanillylamide) is a nonpolar phenol, which is why washing skin that has come in contact with capsaicin with water or vinegar alone is insufficient to solubilize it.¹³ Capsaicin binds to the transient receptor potential vanilloid 1 (TRPV1), a calcium channel on neurons that opens in response to heat. When bound, the channel opens at a lower temperature threshold and depolarizes nerve endings, leading to vasodilation and activation of sensory nerves.¹⁴ Substance P is released and the individual experiences a painful burning sensation. When purified capsaicin is frequently applied at an appropriate dose, synthesis of substance P is diminished, resulting in reduced local pain overall.¹⁵

Capsaicin does not affect neurons without TRPV1, and administration of capsaicin is not painful if given with anesthesia. An inappropriately high dose of capsaicin destroys cells in the epidermal barrier, resulting in water loss and inducing release of vasoactive peptides and inflammatory cytokines.¹ Careful handling of Capsicum peppers and capsaicin products can reduce the risk for irritation.

Medicinal Use

On-/Off-Label and Potential Uses—Capsaicin is US Food and Drug Administration approved for use in arthritis and musculoskeletal pain. It also is used to treat diabetic neuropathy,⁵ postherpetic neuralgia,⁶ psoriasis,¹⁶ and other conditions. Studies have shown that capsaicin might be useful in treating trigeminal neuralgia,¹⁷ fibromyalgia,¹⁸ migraines,¹⁴ cluster headaches,⁹ and HIV-associated distal sensory neuropathy.⁵

Delivery of Capsaicin—Capsaicin preferentially acts on C-fibers, which transmit dull, aching, chronic pain.¹⁹ The compound is available as a cream, lotion, and large bandage (for the lower back), as well as low- and high-dose patches. Capsaicin creams, lotions, and the low-dose patch are uncomfortable and must be applied for 4 to 6 weeks to take effect, which may impact patient adherence. The high-dose patch, which requires administration under local anesthesia by a health care worker, brings pain relief with a single use and improves adherence.¹¹ Synthetic TRPV1-agonist injectables based on capsaicin have undergone clinical trials for localized pain (eg, postoperative musculoskeletal pain); many patients experience pain relief, though benefit fades over weeks to months.^20,21

Use in Traditional Medicine—Capsicum peppers have been used to aid digestion and promote healing in gastrointestinal conditions, such as dyspepsia.²² The peppers are a source of important vitamins and minerals, including vitamins A, C, and E; many of the B complex vitamins; and magnesium, calcium, and iron.²³

Use as Cancer Therapy—Studies of the use of capsaicin in treating cancer have produced controversial results. In cell and animal models, capsaicin induces apoptosis through downregulation of the Bcl-2 protein; upregulation of oxidative stress, tribbles-related protein 3 (TRIB3), and caspase-3; and other pathways.^19,24-26 On the other hand, consumption of Capsicum peppers has been associated with cancer of the stomach and gallbladder.²⁷ Capsaicin might have anticarcinogenic properties, but its mechanism of action varies, depending on variables not fully understood.

Final Thoughts

Capsaicin is a neuropeptide-active compound found in Capsicum peppers that has many promising applications for use. However, dermatologists should be aware of the possibility of a skin reaction to this compound from handling peppers and using topical medicines. Exposure to capsaicin can cause irritant contact dermatitis that may require clinical care.

Cutaneous Manifestations

Capsicum peppers are used worldwide in preparing spicy dishes. Their active ingredient—capsaicin—is used as a topical medicine to treat localized pain. Capsicum peppers can cause irritant contact dermatitis with symptoms of erythema, cutaneous burning, and itch.¹

Irritant contact dermatitis is a common occupational skin disorder. Many cooks have experienced the sting of a chili pepper after contact with the hands or eyes. Cases of chronic exposure to Capsicum peppers with persistent burning and pain have been called Hunan hand syndrome.² Capsicum peppers also have induced allergic contact dermatitis in a food production worker.³

Capsicum peppers also are used in pepper spray, tear gas, and animal repellents because of their stinging properties. These agents usually cause cutaneous tingling and burning that soon resolves; however, a review of 31 studies showed that crowd-control methods with Capsicum-containing tear gas and pepper spray can cause moderate to severe skin damage such as a persistent skin rash or erythema, or even first-, second-, or third-degree burns.⁴

Topical application of capsaicin isolate is meant to cause burning and deplete local neuropeptides, with a cutaneous reaction that ranges from mild to intolerable.^5,6 Capsaicin also is found in other products. In one published case report, a 3-year-old boy broke out in facial urticaria when his mother kissed him on the cheek after she applied lip plumper containing capsaicin to her lips.⁷ Dermatologists should consider capsaicin an active ingredient that can irritate the skin in the garden, in the kitchen, and in topical products.

Obtaining Relief

Capsaicin-induced dermatitis can be relieved by washing the area with soap, detergent, baking soda, or oily compounds that act as solvents for the nonpolar capsaicin.⁸ Application of ice water or a high-potency topical steroid also may help. If the reaction is severe and persistent, a continuous stellate ganglion block may alleviate the pain of capsaicin-induced contact dermatitis.⁹

Identifying Features and Plant Facts

The Capsicum genus includes chili peppers, paprika, and red peppers. Capsicum peppers are native to tropical regions of the Americas (Figure). The use of Capsicum peppers in food can be traced to Indigenous peoples of Mexico as early as 7000 bc.¹⁰ On the Scoville scale, which was developed to quantify the hotness of foods and spices, Capsicum peppers are rated at approximately 2 million units; by comparison, jalapeño peppers have a Scoville score of 4500¹¹ and capsaicin isolate has a score of 16 million units. Capsicum species rank among the hottest peppers in the world.

Capsicum belongs to the family Solanaceae, which includes tobacco, tomatoes, potatoes, and nightshade plants. There are many varieties of peppers in the Capsicum genus, with 5 domesticated species: Capsicum annuum, Capsicum baccatum, Capsicum chinense, Capsicum frutescens, and Capsicum pubescens. These include bell, poblano, cayenne, tabasco, habanero, and ají peppers, among others. Capsicum species grow as a shrub with flowers that rotate to stellate corollas and rounded berries of different sizes and colors.¹² Capsaicin and other alkaloids are concentrated in the fruit; therefore, Capsicum dermatitis is most commonly induced by contact with the flesh of peppers.

 

 

Irritant Chemicals

Capsaicin (8-methyl-6-nonanoyl vanillylamide) is a nonpolar phenol, which is why washing skin that has come in contact with capsaicin with water or vinegar alone is insufficient to solubilize it.¹³ Capsaicin binds to the transient receptor potential vanilloid 1 (TRPV1), a calcium channel on neurons that opens in response to heat. When bound, the channel opens at a lower temperature threshold and depolarizes nerve endings, leading to vasodilation and activation of sensory nerves.¹⁴ Substance P is released and the individual experiences a painful burning sensation. When purified capsaicin is frequently applied at an appropriate dose, synthesis of substance P is diminished, resulting in reduced local pain overall.¹⁵

Capsaicin does not affect neurons without TRPV1, and administration of capsaicin is not painful if given with anesthesia. An inappropriately high dose of capsaicin destroys cells in the epidermal barrier, resulting in water loss and inducing release of vasoactive peptides and inflammatory cytokines.¹ Careful handling of Capsicum peppers and capsaicin products can reduce the risk for irritation.

Medicinal Use

On-/Off-Label and Potential Uses—Capsaicin is US Food and Drug Administration approved for use in arthritis and musculoskeletal pain. It also is used to treat diabetic neuropathy,⁵ postherpetic neuralgia,⁶ psoriasis,¹⁶ and other conditions. Studies have shown that capsaicin might be useful in treating trigeminal neuralgia,¹⁷ fibromyalgia,¹⁸ migraines,¹⁴ cluster headaches,⁹ and HIV-associated distal sensory neuropathy.⁵

Delivery of Capsaicin—Capsaicin preferentially acts on C-fibers, which transmit dull, aching, chronic pain.¹⁹ The compound is available as a cream, lotion, and large bandage (for the lower back), as well as low- and high-dose patches. Capsaicin creams, lotions, and the low-dose patch are uncomfortable and must be applied for 4 to 6 weeks to take effect, which may impact patient adherence. The high-dose patch, which requires administration under local anesthesia by a health care worker, brings pain relief with a single use and improves adherence.¹¹ Synthetic TRPV1-agonist injectables based on capsaicin have undergone clinical trials for localized pain (eg, postoperative musculoskeletal pain); many patients experience pain relief, though benefit fades over weeks to months.^20,21

Use in Traditional Medicine—Capsicum peppers have been used to aid digestion and promote healing in gastrointestinal conditions, such as dyspepsia.²² The peppers are a source of important vitamins and minerals, including vitamins A, C, and E; many of the B complex vitamins; and magnesium, calcium, and iron.²³

Use as Cancer Therapy—Studies of the use of capsaicin in treating cancer have produced controversial results. In cell and animal models, capsaicin induces apoptosis through downregulation of the Bcl-2 protein; upregulation of oxidative stress, tribbles-related protein 3 (TRIB3), and caspase-3; and other pathways.^19,24-26 On the other hand, consumption of Capsicum peppers has been associated with cancer of the stomach and gallbladder.²⁷ Capsaicin might have anticarcinogenic properties, but its mechanism of action varies, depending on variables not fully understood.

Final Thoughts

Capsaicin is a neuropeptide-active compound found in Capsicum peppers that has many promising applications for use. However, dermatologists should be aware of the possibility of a skin reaction to this compound from handling peppers and using topical medicines. Exposure to capsaicin can cause irritant contact dermatitis that may require clinical care.

Erythema ab igne (EAI)(also known as toasted skin syndrome) was first described in the British Journal of Dermatology in the 20th century, ¹ though it was known by physicians long before. Reticular netlike skin changes were seen in association with patients who spent extended time directly next to a heat source. This association led to the name of this condition, which literally means “redness by fire.” Indeed, EAI induced by chronic heat exposure has been described across the world for centuries. For example, in the cold regions of northern China, people used to sleep on beds of hot bricks called kang to stay warm at night. The people of India’s Kashmir district carried pots of hot coals called kangri next to the skin under large woven shawls to stay warm. In the past, Irish women often spent much time by a turf- or peat-burning fire. Chronic heat exposure in these cases can lead not only to EAI but also to aggressive types of cancer, often with a latency of 30 years or more. ²

More recently, the invention of home central heating led to a stark decrease in the number of cases associated with combustion-based heat, with a transition to etiologies such as use of hot water bottles, electric blankets, and electric space heaters. Over time, technological advances led to ever-increasing potential causes for EAI, such as laptops or cell phones, car heaters and heated seats, heated blankets,^3,4 infrared lamps for food, and even medical devices such as ultrasound-based heating products and convective temperature management systems for hospitalized patients. As technology evolves, so do the potential causes of EAI, requiring clinicians to diagnose and deduce the cause through a thorough social and medical history as well as a workup on the present illness with considerations for the anatomical location.^5-7 Herein, we describe the etiology of EAI, diagnosis, and treatment options.

Clinical Characteristics

Erythema ab igne begins as mild, transient, and erythematous macules and patches in a reticular pattern that resolve minutes to hours after removal of the heat source. With weeks to months of continued or repeated application of the heat source, the affected area eventually becomes hyperpigmented where there once was erythema (Figures 1 and 2). Sometimes papules, bullae, telangiectasia, and hyperkeratosis also form. The rash usually is asymptomatic, though pain, pruritus, and dysesthesia have been reported.⁷ Dermoscopy of EAI in the hyperpigmented stage can reveal diffuse superficial dark pigmentation, telangiectasia, and mild whitish scaling.⁸ Although the pathogenesis has remained elusive over the years, lesions do seem to be mostly associated with cumulative exposure to heat rather than length of exposure.⁷

Etiology of EAI

Anatomic Location—The affected site depends on the source of heat (Table). Classic examples of this condition include a patient with EAI presenting on the anterior thighs after working in front of a hot oven or a patient with chronic back pain presenting with lower-back EAI secondary to frequent use of a hot water bottle or heating pad.⁷ With evolving technology over the last few decades, new etiologies have become more common—teenagers are presenting with anterior thigh EAI secondary to frequent laptop use^2-29; patients are holding warm cell phones in their pant pockets, leading to unilateral geometric EAI on the anterior thigh (front pocket) or buttock (back pocket)³⁰; plug-in radiators under computer desks are causing EAI on the lower legs^31-34; and automobile seat heaters have been shown to cause EAI on the posterior legs.^5,35-37 Clinicians should consider anatomic location a critical clue for etiology.

Social History—There are rarer and more highly specific causes of EAI than simple heat exposure that can be parsed from a patient’s social history. Occupational exposure has been documented, such as bakers with exposure to ovens, foundry workers with exposure to heated metals, or fast-food workers with chronic exposure to infrared food lamps.^6,7 There also are cultural practices that can cause EAI. For example, the practice of cupping with moxibustion was shown to create a specific pattern in the shape of the cultural tool used.³⁸ When footbaths with Chinese herbal remedies are performed frequently with high heat, they can lead to EAI on the feet with a linear border at the ankles. There also have been reports of kotatsu (heated tables in Japan) leading to lower-body EAI.^39,40 These cultural practices also are more common in patients with darker skin types, which can lead to hyperpigmentation that is difficult to treat, making early diagnosis important.⁷

Medical History—Case reports have shown EAI caused by patients attempting to use heat-based methods for pain relief of an underlying serious disease such as cancer, bowel pathology (abdominal EAI), spinal disc prolapse (midline back EAI),⁴¹ sickle cell anemia, and renal pathology (posterior upper flank EAI).^6,7,40-49 Patients with hypothyroidism or anorexia have been noted to have generalized EAI sparing the face secondary to repeated and extended hot baths or showers.^50-53 One patient with schizophrenia was shown to have associated thermophilia due to a delusion that led the patient to soak in hot baths for long periods of time, leading to EAI.⁵⁴ Finally, all physicians should be aware of iatrogenic causes of EAI, such as use of warming devices, ultrasound-based warming techniques, and laser therapy for lipolysis. Inquire about the patient’s surgical history or intensive care unit stays as well as alternative medicine or chiropractic visits. Obtaining a history of medical procedures can be enlightening when an etiology is not immediately clear.^7,55,56

Diagnosis

Erythema ab igne is a clinical diagnosis based on recognizable cutaneous findings and a clear history of moderate heat exposure. However, when a clinical diagnosis of EAI is not certain (eg, when unable to obtain a clear history from the patient) or when malignant transformation is suspected, a biopsy can be performed. Pathologically, hematoxylin and eosin staining of EAI classically reveals dilated small vascular channels in the superficial dermis, hence a clinically reticular rash; interface dermatitis clinically manifesting as erythema; and pigment incontinence with melanin-laden macrophages consistent with clinical hyperpigmentation. Finally, for unclear reasons, increased numbers of elastic fibers classically are seen in biopsies of EAI.⁷

 

 

Differential Diagnosis

The differential diagnosis for a reticular patch includes livedo reticularis (Figure 3), which usually manifests as a more generalized rash in patients with chronic disease or coagulopathy such as systemic lupus erythematosus, cryoglobulinemia, or Raynaud phenomenon. When differentiating EAI from livedo reticularis or cutis marmorata, consider that both alternative diagnoses are more vascular appearing and are associated with cold exposure rather than heat exposure. In cases that are less reticular, livedo racemosa can be considered in the differential diagnosis. Finally, poikiloderma of Civatte can be reticular, particularly on dermoscopy, but the distribution on the neck with submental sparing should help to distinguish it from EAI unless a heat source around the neck is identified while taking the patient’s history.⁷

In babies, a reticular generalized rash is most likely to be cutis marmorata (Figure 4), which is a physiologic response to cold exposure that resolves with rewarming of the skin. A more serious condition—cutis marmorata telangiectatica congenita (Figure 5)—usually is present at birth, most frequently involves a single extremity, and notably does not resolve with rewarming. This is an important differential for EAI in children because it can be associated with vascular and neurologic anomalies as well as limb asymmetry. Finally, port-wine stains can sometimes be reticular in appearance and can mimic the early erythematous stages of EAI. However, unlike the erythematous stage of EAI, the port-wine stains will be present at birth.⁷

Emerging in 2020, an important differential diagnosis to consider is a cutaneous manifestation of COVID-19 infection. An erythematous, reticular, chilblainlike or transient livedo reticularis–like rash has been described as a cutaneous manifestation of COVID-19. Although the pathophysiology is still being elucidated, it is suspected that this is caused by a major vaso-occlusive crisis secondary to COVID-19–induced thrombotic vasculopathy. Interestingly, the majority of patients with this COVID-related exanthem also displayed symptoms of COVID-19 (eg, fever, cough) at the time of presentation,^57-60 but there also have been cases in patients who were asymptomatic or mildly symptomatic.⁶⁰

In some cases, EAI is an indication to screen for an underlying disease. For example, uncontrolled pain is an opportunity to improve interventions such as modifying the patient’s pain-control regimen, placing a palliative care pain consultation, or checking if the patient has had age-appropriate screenings for malignancy. New focal pain in a patient with a prior diagnosis of cancer may be a sign of a new metastasis. A thermophilic patient leaves opportunity to assess for underlying medical causes such as thyroid abnormalities or social/psychological issues. Geriatric patients who are diagnosed with EAI may need to be assessed for dementia or home safety issues. Patients with a history of diabetes mellitus can unknowingly develop EAI on the lower extremities, which may signal a need to assess the patient for peripheral neuropathy. Patients with gastroparesis secondary to diabetes also may develop EAI on the abdomen secondary to heating pad use for discomfort. These examples are a reminder to consider possible secondary comorbidities in all diagnoses of EAI.⁷ 

Prognosis

Although the prognosis of EAI is excellent if caught early, failure to diagnose this condition can lead to permanent discoloration of the skin and even malignancy.⁶ A rare sequela includes squamous cell carcinoma, most commonly seen in chronic cases of the lower leg, which is likely related to chronic inflammation of the skin.^61-65 Rare cases of poorly differentiated carcinoma,⁶⁶ cutaneous marginal zone lymphoma,⁶⁷ and Merkel cell carcinoma⁶⁸ have been reported. Patients diagnosed with EAI should receive normal periodic surveillance of the skin based on their medical history, though the physician should have an increased suspicion and plan for biopsy of any nodules or ulcerations found on the skin of the affected area.⁷

Treatments

Once the diagnosis of EAI is made, treatment starts with removal of the heat source causing the rash. Because the rash usually is asymptomatic, further treatment typically is not required. The discoloration can resolve over months or years, but permanent hyperpigmentation is not uncommon. If hyperpigmentation persists despite removal of the heat source and the patient desires further treatment for discoloration, there are few treatment options, none of which are approved by the US Food and Drug Administration for this condition.⁷ There is some evidence for the use of Nd:YAG lasers to reduce hyperpigmentation in EAI.⁶⁹ There have been some reports of treatment using topical hydroquinone and topical tretinoin in an attempt to lighten the skin. If associated hyperkeratosis or other epithelial atypia is present, the use of 5-fluorouracil may show some improvement.⁷⁰ One case report has been published of successful treatment with systemic mesoglycan and topical bioflavonoids.⁷¹ It also is conceivable that medications used to treat postinflammatory hyperpigmentation may be helpful in this condition (eg, kojic acid, arbutin, mild topical steroids, azelaic acid). Patients with darker skin may experience permanent discoloration and may not be good candidates for alternative treatments such as laser therapy due to the risk for inducible hyperpigmentation.⁷

Conclusion

No matter the etiology, EAI usually is a benign skin condition that is treated by removal of the causative heat source. Once a diagnosis is made, the clinician must work with the patient to determine the etiology. Care must be taken to ensure that there are no underlying signs, such as chronic pain or psychiatric illness, that could point to associated conditions. Rarely, sequalae such as cancers have been documented in areas of chronic EAI. Once the heat source is identified and removed, any remaining hyperpigmentation usually will self-resolve over months to years, though this may take longer in patients with darker skin types. If more aggressive treatment is preferred by the patient, laser therapy, topical medications, and oral over-the-counter vitamins have been tried with minimal responses. 

Erythema ab igne (EAI)(also known as toasted skin syndrome) was first described in the British Journal of Dermatology in the 20th century, ¹ though it was known by physicians long before. Reticular netlike skin changes were seen in association with patients who spent extended time directly next to a heat source. This association led to the name of this condition, which literally means “redness by fire.” Indeed, EAI induced by chronic heat exposure has been described across the world for centuries. For example, in the cold regions of northern China, people used to sleep on beds of hot bricks called kang to stay warm at night. The people of India’s Kashmir district carried pots of hot coals called kangri next to the skin under large woven shawls to stay warm. In the past, Irish women often spent much time by a turf- or peat-burning fire. Chronic heat exposure in these cases can lead not only to EAI but also to aggressive types of cancer, often with a latency of 30 years or more. ²

More recently, the invention of home central heating led to a stark decrease in the number of cases associated with combustion-based heat, with a transition to etiologies such as use of hot water bottles, electric blankets, and electric space heaters. Over time, technological advances led to ever-increasing potential causes for EAI, such as laptops or cell phones, car heaters and heated seats, heated blankets,^3,4 infrared lamps for food, and even medical devices such as ultrasound-based heating products and convective temperature management systems for hospitalized patients. As technology evolves, so do the potential causes of EAI, requiring clinicians to diagnose and deduce the cause through a thorough social and medical history as well as a workup on the present illness with considerations for the anatomical location.^5-7 Herein, we describe the etiology of EAI, diagnosis, and treatment options.

Clinical Characteristics

Erythema ab igne begins as mild, transient, and erythematous macules and patches in a reticular pattern that resolve minutes to hours after removal of the heat source. With weeks to months of continued or repeated application of the heat source, the affected area eventually becomes hyperpigmented where there once was erythema (Figures 1 and 2). Sometimes papules, bullae, telangiectasia, and hyperkeratosis also form. The rash usually is asymptomatic, though pain, pruritus, and dysesthesia have been reported.⁷ Dermoscopy of EAI in the hyperpigmented stage can reveal diffuse superficial dark pigmentation, telangiectasia, and mild whitish scaling.⁸ Although the pathogenesis has remained elusive over the years, lesions do seem to be mostly associated with cumulative exposure to heat rather than length of exposure.⁷

Etiology of EAI

Anatomic Location—The affected site depends on the source of heat (Table). Classic examples of this condition include a patient with EAI presenting on the anterior thighs after working in front of a hot oven or a patient with chronic back pain presenting with lower-back EAI secondary to frequent use of a hot water bottle or heating pad.⁷ With evolving technology over the last few decades, new etiologies have become more common—teenagers are presenting with anterior thigh EAI secondary to frequent laptop use^2-29; patients are holding warm cell phones in their pant pockets, leading to unilateral geometric EAI on the anterior thigh (front pocket) or buttock (back pocket)³⁰; plug-in radiators under computer desks are causing EAI on the lower legs^31-34; and automobile seat heaters have been shown to cause EAI on the posterior legs.^5,35-37 Clinicians should consider anatomic location a critical clue for etiology.

Social History—There are rarer and more highly specific causes of EAI than simple heat exposure that can be parsed from a patient’s social history. Occupational exposure has been documented, such as bakers with exposure to ovens, foundry workers with exposure to heated metals, or fast-food workers with chronic exposure to infrared food lamps.^6,7 There also are cultural practices that can cause EAI. For example, the practice of cupping with moxibustion was shown to create a specific pattern in the shape of the cultural tool used.³⁸ When footbaths with Chinese herbal remedies are performed frequently with high heat, they can lead to EAI on the feet with a linear border at the ankles. There also have been reports of kotatsu (heated tables in Japan) leading to lower-body EAI.^39,40 These cultural practices also are more common in patients with darker skin types, which can lead to hyperpigmentation that is difficult to treat, making early diagnosis important.⁷

Medical History—Case reports have shown EAI caused by patients attempting to use heat-based methods for pain relief of an underlying serious disease such as cancer, bowel pathology (abdominal EAI), spinal disc prolapse (midline back EAI),⁴¹ sickle cell anemia, and renal pathology (posterior upper flank EAI).^6,7,40-49 Patients with hypothyroidism or anorexia have been noted to have generalized EAI sparing the face secondary to repeated and extended hot baths or showers.^50-53 One patient with schizophrenia was shown to have associated thermophilia due to a delusion that led the patient to soak in hot baths for long periods of time, leading to EAI.⁵⁴ Finally, all physicians should be aware of iatrogenic causes of EAI, such as use of warming devices, ultrasound-based warming techniques, and laser therapy for lipolysis. Inquire about the patient’s surgical history or intensive care unit stays as well as alternative medicine or chiropractic visits. Obtaining a history of medical procedures can be enlightening when an etiology is not immediately clear.^7,55,56

Diagnosis

Erythema ab igne is a clinical diagnosis based on recognizable cutaneous findings and a clear history of moderate heat exposure. However, when a clinical diagnosis of EAI is not certain (eg, when unable to obtain a clear history from the patient) or when malignant transformation is suspected, a biopsy can be performed. Pathologically, hematoxylin and eosin staining of EAI classically reveals dilated small vascular channels in the superficial dermis, hence a clinically reticular rash; interface dermatitis clinically manifesting as erythema; and pigment incontinence with melanin-laden macrophages consistent with clinical hyperpigmentation. Finally, for unclear reasons, increased numbers of elastic fibers classically are seen in biopsies of EAI.⁷

 

 

Differential Diagnosis

The differential diagnosis for a reticular patch includes livedo reticularis (Figure 3), which usually manifests as a more generalized rash in patients with chronic disease or coagulopathy such as systemic lupus erythematosus, cryoglobulinemia, or Raynaud phenomenon. When differentiating EAI from livedo reticularis or cutis marmorata, consider that both alternative diagnoses are more vascular appearing and are associated with cold exposure rather than heat exposure. In cases that are less reticular, livedo racemosa can be considered in the differential diagnosis. Finally, poikiloderma of Civatte can be reticular, particularly on dermoscopy, but the distribution on the neck with submental sparing should help to distinguish it from EAI unless a heat source around the neck is identified while taking the patient’s history.⁷

In babies, a reticular generalized rash is most likely to be cutis marmorata (Figure 4), which is a physiologic response to cold exposure that resolves with rewarming of the skin. A more serious condition—cutis marmorata telangiectatica congenita (Figure 5)—usually is present at birth, most frequently involves a single extremity, and notably does not resolve with rewarming. This is an important differential for EAI in children because it can be associated with vascular and neurologic anomalies as well as limb asymmetry. Finally, port-wine stains can sometimes be reticular in appearance and can mimic the early erythematous stages of EAI. However, unlike the erythematous stage of EAI, the port-wine stains will be present at birth.⁷

Emerging in 2020, an important differential diagnosis to consider is a cutaneous manifestation of COVID-19 infection. An erythematous, reticular, chilblainlike or transient livedo reticularis–like rash has been described as a cutaneous manifestation of COVID-19. Although the pathophysiology is still being elucidated, it is suspected that this is caused by a major vaso-occlusive crisis secondary to COVID-19–induced thrombotic vasculopathy. Interestingly, the majority of patients with this COVID-related exanthem also displayed symptoms of COVID-19 (eg, fever, cough) at the time of presentation,^57-60 but there also have been cases in patients who were asymptomatic or mildly symptomatic.⁶⁰

In some cases, EAI is an indication to screen for an underlying disease. For example, uncontrolled pain is an opportunity to improve interventions such as modifying the patient’s pain-control regimen, placing a palliative care pain consultation, or checking if the patient has had age-appropriate screenings for malignancy. New focal pain in a patient with a prior diagnosis of cancer may be a sign of a new metastasis. A thermophilic patient leaves opportunity to assess for underlying medical causes such as thyroid abnormalities or social/psychological issues. Geriatric patients who are diagnosed with EAI may need to be assessed for dementia or home safety issues. Patients with a history of diabetes mellitus can unknowingly develop EAI on the lower extremities, which may signal a need to assess the patient for peripheral neuropathy. Patients with gastroparesis secondary to diabetes also may develop EAI on the abdomen secondary to heating pad use for discomfort. These examples are a reminder to consider possible secondary comorbidities in all diagnoses of EAI.⁷ 

Prognosis

Although the prognosis of EAI is excellent if caught early, failure to diagnose this condition can lead to permanent discoloration of the skin and even malignancy.⁶ A rare sequela includes squamous cell carcinoma, most commonly seen in chronic cases of the lower leg, which is likely related to chronic inflammation of the skin.^61-65 Rare cases of poorly differentiated carcinoma,⁶⁶ cutaneous marginal zone lymphoma,⁶⁷ and Merkel cell carcinoma⁶⁸ have been reported. Patients diagnosed with EAI should receive normal periodic surveillance of the skin based on their medical history, though the physician should have an increased suspicion and plan for biopsy of any nodules or ulcerations found on the skin of the affected area.⁷

Treatments

Once the diagnosis of EAI is made, treatment starts with removal of the heat source causing the rash. Because the rash usually is asymptomatic, further treatment typically is not required. The discoloration can resolve over months or years, but permanent hyperpigmentation is not uncommon. If hyperpigmentation persists despite removal of the heat source and the patient desires further treatment for discoloration, there are few treatment options, none of which are approved by the US Food and Drug Administration for this condition.⁷ There is some evidence for the use of Nd:YAG lasers to reduce hyperpigmentation in EAI.⁶⁹ There have been some reports of treatment using topical hydroquinone and topical tretinoin in an attempt to lighten the skin. If associated hyperkeratosis or other epithelial atypia is present, the use of 5-fluorouracil may show some improvement.⁷⁰ One case report has been published of successful treatment with systemic mesoglycan and topical bioflavonoids.⁷¹ It also is conceivable that medications used to treat postinflammatory hyperpigmentation may be helpful in this condition (eg, kojic acid, arbutin, mild topical steroids, azelaic acid). Patients with darker skin may experience permanent discoloration and may not be good candidates for alternative treatments such as laser therapy due to the risk for inducible hyperpigmentation.⁷

Conclusion

No matter the etiology, EAI usually is a benign skin condition that is treated by removal of the causative heat source. Once a diagnosis is made, the clinician must work with the patient to determine the etiology. Care must be taken to ensure that there are no underlying signs, such as chronic pain or psychiatric illness, that could point to associated conditions. Rarely, sequalae such as cancers have been documented in areas of chronic EAI. Once the heat source is identified and removed, any remaining hyperpigmentation usually will self-resolve over months to years, though this may take longer in patients with darker skin types. If more aggressive treatment is preferred by the patient, laser therapy, topical medications, and oral over-the-counter vitamins have been tried with minimal responses. 

Erythema ab igne (EAI)(also known as toasted skin syndrome) was first described in the British Journal of Dermatology in the 20th century, ¹ though it was known by physicians long before. Reticular netlike skin changes were seen in association with patients who spent extended time directly next to a heat source. This association led to the name of this condition, which literally means “redness by fire.” Indeed, EAI induced by chronic heat exposure has been described across the world for centuries. For example, in the cold regions of northern China, people used to sleep on beds of hot bricks called kang to stay warm at night. The people of India’s Kashmir district carried pots of hot coals called kangri next to the skin under large woven shawls to stay warm. In the past, Irish women often spent much time by a turf- or peat-burning fire. Chronic heat exposure in these cases can lead not only to EAI but also to aggressive types of cancer, often with a latency of 30 years or more. ²

More recently, the invention of home central heating led to a stark decrease in the number of cases associated with combustion-based heat, with a transition to etiologies such as use of hot water bottles, electric blankets, and electric space heaters. Over time, technological advances led to ever-increasing potential causes for EAI, such as laptops or cell phones, car heaters and heated seats, heated blankets,^3,4 infrared lamps for food, and even medical devices such as ultrasound-based heating products and convective temperature management systems for hospitalized patients. As technology evolves, so do the potential causes of EAI, requiring clinicians to diagnose and deduce the cause through a thorough social and medical history as well as a workup on the present illness with considerations for the anatomical location.^5-7 Herein, we describe the etiology of EAI, diagnosis, and treatment options.

Clinical Characteristics

Erythema ab igne begins as mild, transient, and erythematous macules and patches in a reticular pattern that resolve minutes to hours after removal of the heat source. With weeks to months of continued or repeated application of the heat source, the affected area eventually becomes hyperpigmented where there once was erythema (Figures 1 and 2). Sometimes papules, bullae, telangiectasia, and hyperkeratosis also form. The rash usually is asymptomatic, though pain, pruritus, and dysesthesia have been reported.⁷ Dermoscopy of EAI in the hyperpigmented stage can reveal diffuse superficial dark pigmentation, telangiectasia, and mild whitish scaling.⁸ Although the pathogenesis has remained elusive over the years, lesions do seem to be mostly associated with cumulative exposure to heat rather than length of exposure.⁷

Etiology of EAI

Anatomic Location—The affected site depends on the source of heat (Table). Classic examples of this condition include a patient with EAI presenting on the anterior thighs after working in front of a hot oven or a patient with chronic back pain presenting with lower-back EAI secondary to frequent use of a hot water bottle or heating pad.⁷ With evolving technology over the last few decades, new etiologies have become more common—teenagers are presenting with anterior thigh EAI secondary to frequent laptop use^2-29; patients are holding warm cell phones in their pant pockets, leading to unilateral geometric EAI on the anterior thigh (front pocket) or buttock (back pocket)³⁰; plug-in radiators under computer desks are causing EAI on the lower legs^31-34; and automobile seat heaters have been shown to cause EAI on the posterior legs.^5,35-37 Clinicians should consider anatomic location a critical clue for etiology.

Social History—There are rarer and more highly specific causes of EAI than simple heat exposure that can be parsed from a patient’s social history. Occupational exposure has been documented, such as bakers with exposure to ovens, foundry workers with exposure to heated metals, or fast-food workers with chronic exposure to infrared food lamps.^6,7 There also are cultural practices that can cause EAI. For example, the practice of cupping with moxibustion was shown to create a specific pattern in the shape of the cultural tool used.³⁸ When footbaths with Chinese herbal remedies are performed frequently with high heat, they can lead to EAI on the feet with a linear border at the ankles. There also have been reports of kotatsu (heated tables in Japan) leading to lower-body EAI.^39,40 These cultural practices also are more common in patients with darker skin types, which can lead to hyperpigmentation that is difficult to treat, making early diagnosis important.⁷

Medical History—Case reports have shown EAI caused by patients attempting to use heat-based methods for pain relief of an underlying serious disease such as cancer, bowel pathology (abdominal EAI), spinal disc prolapse (midline back EAI),⁴¹ sickle cell anemia, and renal pathology (posterior upper flank EAI).^6,7,40-49 Patients with hypothyroidism or anorexia have been noted to have generalized EAI sparing the face secondary to repeated and extended hot baths or showers.^50-53 One patient with schizophrenia was shown to have associated thermophilia due to a delusion that led the patient to soak in hot baths for long periods of time, leading to EAI.⁵⁴ Finally, all physicians should be aware of iatrogenic causes of EAI, such as use of warming devices, ultrasound-based warming techniques, and laser therapy for lipolysis. Inquire about the patient’s surgical history or intensive care unit stays as well as alternative medicine or chiropractic visits. Obtaining a history of medical procedures can be enlightening when an etiology is not immediately clear.^7,55,56

Diagnosis

Erythema ab igne is a clinical diagnosis based on recognizable cutaneous findings and a clear history of moderate heat exposure. However, when a clinical diagnosis of EAI is not certain (eg, when unable to obtain a clear history from the patient) or when malignant transformation is suspected, a biopsy can be performed. Pathologically, hematoxylin and eosin staining of EAI classically reveals dilated small vascular channels in the superficial dermis, hence a clinically reticular rash; interface dermatitis clinically manifesting as erythema; and pigment incontinence with melanin-laden macrophages consistent with clinical hyperpigmentation. Finally, for unclear reasons, increased numbers of elastic fibers classically are seen in biopsies of EAI.⁷

 

 

Differential Diagnosis

The differential diagnosis for a reticular patch includes livedo reticularis (Figure 3), which usually manifests as a more generalized rash in patients with chronic disease or coagulopathy such as systemic lupus erythematosus, cryoglobulinemia, or Raynaud phenomenon. When differentiating EAI from livedo reticularis or cutis marmorata, consider that both alternative diagnoses are more vascular appearing and are associated with cold exposure rather than heat exposure. In cases that are less reticular, livedo racemosa can be considered in the differential diagnosis. Finally, poikiloderma of Civatte can be reticular, particularly on dermoscopy, but the distribution on the neck with submental sparing should help to distinguish it from EAI unless a heat source around the neck is identified while taking the patient’s history.⁷

In babies, a reticular generalized rash is most likely to be cutis marmorata (Figure 4), which is a physiologic response to cold exposure that resolves with rewarming of the skin. A more serious condition—cutis marmorata telangiectatica congenita (Figure 5)—usually is present at birth, most frequently involves a single extremity, and notably does not resolve with rewarming. This is an important differential for EAI in children because it can be associated with vascular and neurologic anomalies as well as limb asymmetry. Finally, port-wine stains can sometimes be reticular in appearance and can mimic the early erythematous stages of EAI. However, unlike the erythematous stage of EAI, the port-wine stains will be present at birth.⁷

Emerging in 2020, an important differential diagnosis to consider is a cutaneous manifestation of COVID-19 infection. An erythematous, reticular, chilblainlike or transient livedo reticularis–like rash has been described as a cutaneous manifestation of COVID-19. Although the pathophysiology is still being elucidated, it is suspected that this is caused by a major vaso-occlusive crisis secondary to COVID-19–induced thrombotic vasculopathy. Interestingly, the majority of patients with this COVID-related exanthem also displayed symptoms of COVID-19 (eg, fever, cough) at the time of presentation,^57-60 but there also have been cases in patients who were asymptomatic or mildly symptomatic.⁶⁰

In some cases, EAI is an indication to screen for an underlying disease. For example, uncontrolled pain is an opportunity to improve interventions such as modifying the patient’s pain-control regimen, placing a palliative care pain consultation, or checking if the patient has had age-appropriate screenings for malignancy. New focal pain in a patient with a prior diagnosis of cancer may be a sign of a new metastasis. A thermophilic patient leaves opportunity to assess for underlying medical causes such as thyroid abnormalities or social/psychological issues. Geriatric patients who are diagnosed with EAI may need to be assessed for dementia or home safety issues. Patients with a history of diabetes mellitus can unknowingly develop EAI on the lower extremities, which may signal a need to assess the patient for peripheral neuropathy. Patients with gastroparesis secondary to diabetes also may develop EAI on the abdomen secondary to heating pad use for discomfort. These examples are a reminder to consider possible secondary comorbidities in all diagnoses of EAI.⁷ 

Prognosis

Although the prognosis of EAI is excellent if caught early, failure to diagnose this condition can lead to permanent discoloration of the skin and even malignancy.⁶ A rare sequela includes squamous cell carcinoma, most commonly seen in chronic cases of the lower leg, which is likely related to chronic inflammation of the skin.^61-65 Rare cases of poorly differentiated carcinoma,⁶⁶ cutaneous marginal zone lymphoma,⁶⁷ and Merkel cell carcinoma⁶⁸ have been reported. Patients diagnosed with EAI should receive normal periodic surveillance of the skin based on their medical history, though the physician should have an increased suspicion and plan for biopsy of any nodules or ulcerations found on the skin of the affected area.⁷

Treatments

Once the diagnosis of EAI is made, treatment starts with removal of the heat source causing the rash. Because the rash usually is asymptomatic, further treatment typically is not required. The discoloration can resolve over months or years, but permanent hyperpigmentation is not uncommon. If hyperpigmentation persists despite removal of the heat source and the patient desires further treatment for discoloration, there are few treatment options, none of which are approved by the US Food and Drug Administration for this condition.⁷ There is some evidence for the use of Nd:YAG lasers to reduce hyperpigmentation in EAI.⁶⁹ There have been some reports of treatment using topical hydroquinone and topical tretinoin in an attempt to lighten the skin. If associated hyperkeratosis or other epithelial atypia is present, the use of 5-fluorouracil may show some improvement.⁷⁰ One case report has been published of successful treatment with systemic mesoglycan and topical bioflavonoids.⁷¹ It also is conceivable that medications used to treat postinflammatory hyperpigmentation may be helpful in this condition (eg, kojic acid, arbutin, mild topical steroids, azelaic acid). Patients with darker skin may experience permanent discoloration and may not be good candidates for alternative treatments such as laser therapy due to the risk for inducible hyperpigmentation.⁷

Conclusion

No matter the etiology, EAI usually is a benign skin condition that is treated by removal of the causative heat source. Once a diagnosis is made, the clinician must work with the patient to determine the etiology. Care must be taken to ensure that there are no underlying signs, such as chronic pain or psychiatric illness, that could point to associated conditions. Rarely, sequalae such as cancers have been documented in areas of chronic EAI. Once the heat source is identified and removed, any remaining hyperpigmentation usually will self-resolve over months to years, though this may take longer in patients with darker skin types. If more aggressive treatment is preferred by the patient, laser therapy, topical medications, and oral over-the-counter vitamins have been tried with minimal responses. 

Laundry detergent, a cleaning agent ubiquitous in the modern household, often is suspected as a cause of allergic contact dermatitis (ACD). In one North American study, 10.7% of 738 patients undergoing patch testing believed that laundry detergent was a contributing factor, whereas their referring physicians had the same concern less often (in 2.3% of cases).¹ Likewise, in a 1992 survey of western US households, more than 20% of 3841 respondents reported skin or health problems attributed to a textile and/or laundry product.² The suspicion of laundry detergent as a causative agent of ACD is perpetuated across popular wellness and beauty websites.^3,4 Does the evidence support this degree of suspicion? Or, similar to the well-meaning parent who misguidedly fixates on foods as the cause of their child’s atopic dermatitis and believes elimination diets are the solution,⁵ could a similar desire for control in the face of the unpredictability of eczema drive consumers and health care providers alike to blame laundry detergent—a familiar and modifiable cause?

We provide a summary of the evidence for the potential allergenicity of laundry detergent, including common allergens present in laundry detergent, the role of machine washing, and the differential diagnosis for laundry detergent–associated ACD.

Allergenic Ingredients in Laundry Detergent

Potential allergens present in laundry detergent include fragrances, preservatives, surfactants, emulsifiers, bleaches, brighteners, enzymes, and dyes.^6-8 In an analysis of allergens present in laundry detergents available in the United States, fragrances and preservatives were most common (eTable).^7,8 Contact allergy to fragrances occurs in approximately 3.5% of the general population⁹ and is detected in as many as 9.2% of patients referred for patch testing in North America.¹⁰ Preservatives commonly found in laundry detergent include isothiazolinones, such as methylchloroisothiazolinone (MCI)/methylisothiazolinone (MI), MI alone, and benzisothiazolinone (BIT). Methylisothiazolinone has gained attention for causing an ACD epidemic beginning in the early 2000s and peaking in Europe between 2013 and 2014 and decreasing thereafter due to consumer personal care product regulatory changes enacted in the European Union.¹¹ In contrast, rates of MI allergy in North America have continued to increase (reaching as high as 15% of patch tested patients in 2017-2018) due to a lack of similar regulation.^10,12 More recently, the prevalence of positive patch tests to BIT has been rising, though it often is difficult to ascertain relevant sources of exposure, and some cases could represent cross-reactions to MCI/MI.^10,13

Other allergens that may be present in laundry detergent include surfactants and propylene glycol. Alkyl glucosides such as decyl glucoside and lauryl glucoside are considered gentle surfactants and often are included in products marketed as safe for sensitive skin,¹⁴ such as “free and gentle” detergents.⁸ However, they actually may pose an increased risk for sensitization in patients with atopic dermatitis.¹⁴ In addition to being allergenic, surfactants and emulsifiers are known irritants.^6,15 Although pathologically distinct, ACD and irritant contact dermatitis can be indistinguishable on clinical presentation.

How Commonly Does Laundry Detergent Cause ACD?

The mere presence of a contact allergen in laundry detergent does not necessarily imply that it is likely to cause ACD. To do so, the chemical in question must exceed the exposure thresholds for primary sensitization (ie, induction of contact allergy) and/or elicitation (ie, development of ACD in sensitized individuals). These depend on a complex interplay of product- and patient-specific factors, among them the concentration of the chemical in the detergent, the method of use, and the amount of detergent residue remaining on clothing after washing.

In the 1990s, the North American Contact Dermatitis Group (NACDG) attempted to determine the prevalence of ACD caused by laundry detergent.¹ Among 738 patients patch tested to aqueous dilutions of granular and liquid laundry detergents, only 5 (0.7%) had a possible allergic patch test reaction. It was unclear what the culprit allergens in the detergents may have been; only 1 of the patients also tested positive to fragrance. Two patients underwent further testing to additional detergent dilutions, and the results called into question whether their initial reactions had truly been allergic (positive) or were actually irritant (negative). The investigators concluded that the prevalence of laundry detergent–associated ACD in this large group of patients was at most 0.7%, and possibly lower.¹

Importantly, patch testing to laundry detergents should not be undertaken in routine clinical practice. Laundry detergents should never be tested “as is” (ie, undiluted) on the skin; they are inherently irritating and have a high likelihood of producing misleading false-positive reactions. Careful dilutions and testing of control subjects are necessary if patch testing with these products is to be appropriately conducted.

 

 

Isothiazolinones in Laundry Detergent

The extremely low prevalence of laundry detergent–associated ACD reported by the NACDG was determined prior to the start of the worldwide MI allergy epidemic, raising the possibility that laundry detergents containing isothiazolinones may be associated with ACD. There is no consensus about the minimum level at which isothiazolinones pose no risk to consumers,^16-19 but the US Expert Panel for Cosmetic Ingredient Safety declared that MI is “safe for use in rinse-off cosmetic products at concentrations up to 100 ppm and safe in leave-on cosmetic products when they are formulated to be nonsensitizing.”^18,19 Although ingredient lists do not always reveal when isothiazolinones are present, analyses of commercially available laundry detergents have shown MI concentrations ranging from undetectable to 65.7 ppm.^20-23

Published reports suggest that MCI/MI in laundry detergent can elicit ACD in sensitized individuals. In one case, a 7-year-old girl with chronic truncal dermatitis (atopic history unspecified) was patch tested, revealing a strongly positive reaction to MCI/MI.²⁴ Her laundry detergent was the only personal product found to contain MI. The dermatitis completely resolved after switching detergents and flared after wearing a jacket that had been washed in the implicated detergent, further supporting the relevance of the positive patch test. The investigators suspected initial sensitization to MI from wet wipes used earlier in childhood.²⁴ In another case involving occupational exposure, a 39-year-old nonatopic factory worker was responsible for directly adding MI to laundry detergent.²⁵ Although he wore disposable work gloves, he developed severe hand dermatitis, eczematous pretibial patches, and generalized pruritus. Patch testing revealed positive reactions to MCI/MI and MI, and he experienced improvement when reassigned to different work duties. It was hypothesized that the leg dermatitis and generalized pruritus may have been related to exposure to small concentrations of MI in work clothes washed with an MI-containing detergent.²⁵ Notably, this patient’s level of exposure was much greater than that encountered by individuals in day-to-day life outside of specialized occupational settings.

Regarding other isothiazolinones, a toxicologic study estimated that BIT in laundry detergent would be unlikely to induce sensitization, even at the maximal acceptable concentration, as recommended by preservative manufacturers, and accounting for undiluted detergent spilling directly onto the skin.²⁶ Nonetheless, a single European center recently reported that almost half of the 38 patients with positive patch tests to BIT had a potentially relevant exposure attributed to household cleaning products, including laundry detergent.¹³ This emphasizes the need for further examination of sources of exposure to this increasingly common positive patch test allergen.

Does Machine Washing Impact Allergen Concentrations?

Two recent investigations have suggested that machine washing reduces concentrations of isothiazolinones to levels that are likely below clinical relevance. In the first study, 3 fabrics—cotton, polyester, cotton-polyester—were machine washed and line dried.²⁷ A standard detergent was used with MI added at different concentrations: less than 1 ppm, 100 ppm, and 1000 ppm. This process was either performed once or 10 times. Following laundering and line drying, MI was undetectable in all fabrics regardless of MI concentration or number of times washed (detection limit, 0.5 ppm).²⁷ In the second study, 4 fabrics—cotton, wool, polyester, linen—were washed with standard laundry detergent in 1 of 4 ways: handwashing (positive control), standard machine washing, standard machine washing with fabric softener, and standard machine washing with a double rinse.²⁸ After laundering and line drying, concentrations of MI, MCI, and BIT were low or undetectable regardless of fabric type or method of laundering. The highest levels detected were in handwashed garments at a maximum of 0.5 ppm of MI. The study authors postulated that chemical concentrations near these maximum residual levels may pose a risk for eliciting ACD in highly sensitized individuals. Therefore, handwashing can be considered a much higher risk activity for isothiazolinone ACD compared with machine washing.²⁸

It is intriguing that machine washing appears to reduce isothiazolinones to low concentrations that may have limited likelihood of causing ACD. Similar findings have been reported regarding fragrances. A quantitative risk assessment performed on 24 of 26 fragrance allergens regulated by the European Union determined that the amount of fragrance deposited on the skin from laundered garments would be less than the threshold for causing sensitization.²⁹ Although this risk assessment was unable to address the threshold of elicitation, another study conducted in Europe investigated whether fragrance residues present on fabric, such as those deposited from laundry detergent, are present at high enough concentrations to elicit ACD in previously sensitized individuals.³⁰ When 36 individuals were patch tested with increasing concentrations of a fragrance to which they were already sensitized, only 2 (5.6%) had a weakly positive reaction and then only to the highest concentration, which was estimated to be 20-fold higher than the level of skin exposure after normal laundering. No patient reacted at lower concentrations.³⁰

Although machine washing may decrease isothiazolinone and/or fragrance concentrations in laundry detergent to below clinically relevant levels, these findings should not necessarily be extrapolated to all chemicals in laundry detergent. Indeed, a prior study observed that after washing cotton cloths in a detergent solution for 10 minutes, detergent residue was present at concentrations ranging from 139 to 2820 ppm and required a subsequent 20 to 22 washes in water to become undetectable.³¹ Another study produced a mathematical model of the residual concentration of sodium dodecyl sulphate (SDS), a surfactant and known irritant, in laundered clothing.³² It was estimated that after machine washing, the residual concentration of SDS on clothes would be too low to cause irritation; however, as the clothes dry (ie, as moisture evaporates but solutes remain), the concentration of SDS on the fabric’s surface would increase to potentially irritating levels. The extensive drying that is possible with electric dryers may further enhance this solute-concentrating effect.

Differential Diagnosis of Laundry Detergent ACD

The propensity for laundry detergent to cause ACD is a question that is nowhere near settled, but the prevalence of allergy likely is far less common than is generally suspected. In our experience, many patients presenting for patch testing have already made the change to “free and clear” detergents without noticeable improvement in their dermatitis, which could possibly relate to the ongoing presence of contact allergens in these “gentle” formulations.⁷ However, to avoid anchoring bias, more frequent causes of dermatitis should be included in the differential diagnosis. Textile ACD presents beneath clothing with accentuation at areas of closest contact with the skin, classically involving the axillary rim but sparing the vault. The most frequently implicated allergens in textile ACD are disperse dyes and less commonly textile resins.^33,34 Between 2017 and 2018, 2.3% of 4882 patients patch tested by the NACDG reacted positively to disperse dye mix.¹⁰ There is evidence to suggest that the actual prevalence of disperse dye allergy might be higher due to inadequacy of screening allergens on baseline patch test series.³⁵ Additional diagnoses that should be distinguished from presumed detergent contact dermatitis include atopic dermatitis and cutaneous T-cell lymphoma.

Final Interpretation

Although many patients and physicians consider laundry detergent to be a major cause of ACD, there is limited high-quality evidence to support this belief. Contact allergy to laundry detergent is probably much less common than is widely supposed. Although laundry detergents can contain common allergens such as fragrances and preservatives, evidence suggests that they are likely reduced to below clinically relevant levels during routine machine washing; however, we cannot assume that we are in the “free and clear,” as uncertainty remains about the impact of these low concentrationson individuals with strong contact allergy, and large studies of patch testing to modern detergents have yet to be carried out.

Laundry detergent, a cleaning agent ubiquitous in the modern household, often is suspected as a cause of allergic contact dermatitis (ACD). In one North American study, 10.7% of 738 patients undergoing patch testing believed that laundry detergent was a contributing factor, whereas their referring physicians had the same concern less often (in 2.3% of cases).¹ Likewise, in a 1992 survey of western US households, more than 20% of 3841 respondents reported skin or health problems attributed to a textile and/or laundry product.² The suspicion of laundry detergent as a causative agent of ACD is perpetuated across popular wellness and beauty websites.^3,4 Does the evidence support this degree of suspicion? Or, similar to the well-meaning parent who misguidedly fixates on foods as the cause of their child’s atopic dermatitis and believes elimination diets are the solution,⁵ could a similar desire for control in the face of the unpredictability of eczema drive consumers and health care providers alike to blame laundry detergent—a familiar and modifiable cause?

We provide a summary of the evidence for the potential allergenicity of laundry detergent, including common allergens present in laundry detergent, the role of machine washing, and the differential diagnosis for laundry detergent–associated ACD.

Allergenic Ingredients in Laundry Detergent

Potential allergens present in laundry detergent include fragrances, preservatives, surfactants, emulsifiers, bleaches, brighteners, enzymes, and dyes.^6-8 In an analysis of allergens present in laundry detergents available in the United States, fragrances and preservatives were most common (eTable).^7,8 Contact allergy to fragrances occurs in approximately 3.5% of the general population⁹ and is detected in as many as 9.2% of patients referred for patch testing in North America.¹⁰ Preservatives commonly found in laundry detergent include isothiazolinones, such as methylchloroisothiazolinone (MCI)/methylisothiazolinone (MI), MI alone, and benzisothiazolinone (BIT). Methylisothiazolinone has gained attention for causing an ACD epidemic beginning in the early 2000s and peaking in Europe between 2013 and 2014 and decreasing thereafter due to consumer personal care product regulatory changes enacted in the European Union.¹¹ In contrast, rates of MI allergy in North America have continued to increase (reaching as high as 15% of patch tested patients in 2017-2018) due to a lack of similar regulation.^10,12 More recently, the prevalence of positive patch tests to BIT has been rising, though it often is difficult to ascertain relevant sources of exposure, and some cases could represent cross-reactions to MCI/MI.^10,13

Other allergens that may be present in laundry detergent include surfactants and propylene glycol. Alkyl glucosides such as decyl glucoside and lauryl glucoside are considered gentle surfactants and often are included in products marketed as safe for sensitive skin,¹⁴ such as “free and gentle” detergents.⁸ However, they actually may pose an increased risk for sensitization in patients with atopic dermatitis.¹⁴ In addition to being allergenic, surfactants and emulsifiers are known irritants.^6,15 Although pathologically distinct, ACD and irritant contact dermatitis can be indistinguishable on clinical presentation.

How Commonly Does Laundry Detergent Cause ACD?

The mere presence of a contact allergen in laundry detergent does not necessarily imply that it is likely to cause ACD. To do so, the chemical in question must exceed the exposure thresholds for primary sensitization (ie, induction of contact allergy) and/or elicitation (ie, development of ACD in sensitized individuals). These depend on a complex interplay of product- and patient-specific factors, among them the concentration of the chemical in the detergent, the method of use, and the amount of detergent residue remaining on clothing after washing.

In the 1990s, the North American Contact Dermatitis Group (NACDG) attempted to determine the prevalence of ACD caused by laundry detergent.¹ Among 738 patients patch tested to aqueous dilutions of granular and liquid laundry detergents, only 5 (0.7%) had a possible allergic patch test reaction. It was unclear what the culprit allergens in the detergents may have been; only 1 of the patients also tested positive to fragrance. Two patients underwent further testing to additional detergent dilutions, and the results called into question whether their initial reactions had truly been allergic (positive) or were actually irritant (negative). The investigators concluded that the prevalence of laundry detergent–associated ACD in this large group of patients was at most 0.7%, and possibly lower.¹

Importantly, patch testing to laundry detergents should not be undertaken in routine clinical practice. Laundry detergents should never be tested “as is” (ie, undiluted) on the skin; they are inherently irritating and have a high likelihood of producing misleading false-positive reactions. Careful dilutions and testing of control subjects are necessary if patch testing with these products is to be appropriately conducted.

 

 

Isothiazolinones in Laundry Detergent

The extremely low prevalence of laundry detergent–associated ACD reported by the NACDG was determined prior to the start of the worldwide MI allergy epidemic, raising the possibility that laundry detergents containing isothiazolinones may be associated with ACD. There is no consensus about the minimum level at which isothiazolinones pose no risk to consumers,^16-19 but the US Expert Panel for Cosmetic Ingredient Safety declared that MI is “safe for use in rinse-off cosmetic products at concentrations up to 100 ppm and safe in leave-on cosmetic products when they are formulated to be nonsensitizing.”^18,19 Although ingredient lists do not always reveal when isothiazolinones are present, analyses of commercially available laundry detergents have shown MI concentrations ranging from undetectable to 65.7 ppm.^20-23

Published reports suggest that MCI/MI in laundry detergent can elicit ACD in sensitized individuals. In one case, a 7-year-old girl with chronic truncal dermatitis (atopic history unspecified) was patch tested, revealing a strongly positive reaction to MCI/MI.²⁴ Her laundry detergent was the only personal product found to contain MI. The dermatitis completely resolved after switching detergents and flared after wearing a jacket that had been washed in the implicated detergent, further supporting the relevance of the positive patch test. The investigators suspected initial sensitization to MI from wet wipes used earlier in childhood.²⁴ In another case involving occupational exposure, a 39-year-old nonatopic factory worker was responsible for directly adding MI to laundry detergent.²⁵ Although he wore disposable work gloves, he developed severe hand dermatitis, eczematous pretibial patches, and generalized pruritus. Patch testing revealed positive reactions to MCI/MI and MI, and he experienced improvement when reassigned to different work duties. It was hypothesized that the leg dermatitis and generalized pruritus may have been related to exposure to small concentrations of MI in work clothes washed with an MI-containing detergent.²⁵ Notably, this patient’s level of exposure was much greater than that encountered by individuals in day-to-day life outside of specialized occupational settings.

Regarding other isothiazolinones, a toxicologic study estimated that BIT in laundry detergent would be unlikely to induce sensitization, even at the maximal acceptable concentration, as recommended by preservative manufacturers, and accounting for undiluted detergent spilling directly onto the skin.²⁶ Nonetheless, a single European center recently reported that almost half of the 38 patients with positive patch tests to BIT had a potentially relevant exposure attributed to household cleaning products, including laundry detergent.¹³ This emphasizes the need for further examination of sources of exposure to this increasingly common positive patch test allergen.

Does Machine Washing Impact Allergen Concentrations?

Two recent investigations have suggested that machine washing reduces concentrations of isothiazolinones to levels that are likely below clinical relevance. In the first study, 3 fabrics—cotton, polyester, cotton-polyester—were machine washed and line dried.²⁷ A standard detergent was used with MI added at different concentrations: less than 1 ppm, 100 ppm, and 1000 ppm. This process was either performed once or 10 times. Following laundering and line drying, MI was undetectable in all fabrics regardless of MI concentration or number of times washed (detection limit, 0.5 ppm).²⁷ In the second study, 4 fabrics—cotton, wool, polyester, linen—were washed with standard laundry detergent in 1 of 4 ways: handwashing (positive control), standard machine washing, standard machine washing with fabric softener, and standard machine washing with a double rinse.²⁸ After laundering and line drying, concentrations of MI, MCI, and BIT were low or undetectable regardless of fabric type or method of laundering. The highest levels detected were in handwashed garments at a maximum of 0.5 ppm of MI. The study authors postulated that chemical concentrations near these maximum residual levels may pose a risk for eliciting ACD in highly sensitized individuals. Therefore, handwashing can be considered a much higher risk activity for isothiazolinone ACD compared with machine washing.²⁸

It is intriguing that machine washing appears to reduce isothiazolinones to low concentrations that may have limited likelihood of causing ACD. Similar findings have been reported regarding fragrances. A quantitative risk assessment performed on 24 of 26 fragrance allergens regulated by the European Union determined that the amount of fragrance deposited on the skin from laundered garments would be less than the threshold for causing sensitization.²⁹ Although this risk assessment was unable to address the threshold of elicitation, another study conducted in Europe investigated whether fragrance residues present on fabric, such as those deposited from laundry detergent, are present at high enough concentrations to elicit ACD in previously sensitized individuals.³⁰ When 36 individuals were patch tested with increasing concentrations of a fragrance to which they were already sensitized, only 2 (5.6%) had a weakly positive reaction and then only to the highest concentration, which was estimated to be 20-fold higher than the level of skin exposure after normal laundering. No patient reacted at lower concentrations.³⁰

Although machine washing may decrease isothiazolinone and/or fragrance concentrations in laundry detergent to below clinically relevant levels, these findings should not necessarily be extrapolated to all chemicals in laundry detergent. Indeed, a prior study observed that after washing cotton cloths in a detergent solution for 10 minutes, detergent residue was present at concentrations ranging from 139 to 2820 ppm and required a subsequent 20 to 22 washes in water to become undetectable.³¹ Another study produced a mathematical model of the residual concentration of sodium dodecyl sulphate (SDS), a surfactant and known irritant, in laundered clothing.³² It was estimated that after machine washing, the residual concentration of SDS on clothes would be too low to cause irritation; however, as the clothes dry (ie, as moisture evaporates but solutes remain), the concentration of SDS on the fabric’s surface would increase to potentially irritating levels. The extensive drying that is possible with electric dryers may further enhance this solute-concentrating effect.

Differential Diagnosis of Laundry Detergent ACD

The propensity for laundry detergent to cause ACD is a question that is nowhere near settled, but the prevalence of allergy likely is far less common than is generally suspected. In our experience, many patients presenting for patch testing have already made the change to “free and clear” detergents without noticeable improvement in their dermatitis, which could possibly relate to the ongoing presence of contact allergens in these “gentle” formulations.⁷ However, to avoid anchoring bias, more frequent causes of dermatitis should be included in the differential diagnosis. Textile ACD presents beneath clothing with accentuation at areas of closest contact with the skin, classically involving the axillary rim but sparing the vault. The most frequently implicated allergens in textile ACD are disperse dyes and less commonly textile resins.^33,34 Between 2017 and 2018, 2.3% of 4882 patients patch tested by the NACDG reacted positively to disperse dye mix.¹⁰ There is evidence to suggest that the actual prevalence of disperse dye allergy might be higher due to inadequacy of screening allergens on baseline patch test series.³⁵ Additional diagnoses that should be distinguished from presumed detergent contact dermatitis include atopic dermatitis and cutaneous T-cell lymphoma.

Final Interpretation

Although many patients and physicians consider laundry detergent to be a major cause of ACD, there is limited high-quality evidence to support this belief. Contact allergy to laundry detergent is probably much less common than is widely supposed. Although laundry detergents can contain common allergens such as fragrances and preservatives, evidence suggests that they are likely reduced to below clinically relevant levels during routine machine washing; however, we cannot assume that we are in the “free and clear,” as uncertainty remains about the impact of these low concentrationson individuals with strong contact allergy, and large studies of patch testing to modern detergents have yet to be carried out.

Laundry detergent, a cleaning agent ubiquitous in the modern household, often is suspected as a cause of allergic contact dermatitis (ACD). In one North American study, 10.7% of 738 patients undergoing patch testing believed that laundry detergent was a contributing factor, whereas their referring physicians had the same concern less often (in 2.3% of cases).¹ Likewise, in a 1992 survey of western US households, more than 20% of 3841 respondents reported skin or health problems attributed to a textile and/or laundry product.² The suspicion of laundry detergent as a causative agent of ACD is perpetuated across popular wellness and beauty websites.^3,4 Does the evidence support this degree of suspicion? Or, similar to the well-meaning parent who misguidedly fixates on foods as the cause of their child’s atopic dermatitis and believes elimination diets are the solution,⁵ could a similar desire for control in the face of the unpredictability of eczema drive consumers and health care providers alike to blame laundry detergent—a familiar and modifiable cause?

We provide a summary of the evidence for the potential allergenicity of laundry detergent, including common allergens present in laundry detergent, the role of machine washing, and the differential diagnosis for laundry detergent–associated ACD.

Allergenic Ingredients in Laundry Detergent

Potential allergens present in laundry detergent include fragrances, preservatives, surfactants, emulsifiers, bleaches, brighteners, enzymes, and dyes.^6-8 In an analysis of allergens present in laundry detergents available in the United States, fragrances and preservatives were most common (eTable).^7,8 Contact allergy to fragrances occurs in approximately 3.5% of the general population⁹ and is detected in as many as 9.2% of patients referred for patch testing in North America.¹⁰ Preservatives commonly found in laundry detergent include isothiazolinones, such as methylchloroisothiazolinone (MCI)/methylisothiazolinone (MI), MI alone, and benzisothiazolinone (BIT). Methylisothiazolinone has gained attention for causing an ACD epidemic beginning in the early 2000s and peaking in Europe between 2013 and 2014 and decreasing thereafter due to consumer personal care product regulatory changes enacted in the European Union.¹¹ In contrast, rates of MI allergy in North America have continued to increase (reaching as high as 15% of patch tested patients in 2017-2018) due to a lack of similar regulation.^10,12 More recently, the prevalence of positive patch tests to BIT has been rising, though it often is difficult to ascertain relevant sources of exposure, and some cases could represent cross-reactions to MCI/MI.^10,13

Other allergens that may be present in laundry detergent include surfactants and propylene glycol. Alkyl glucosides such as decyl glucoside and lauryl glucoside are considered gentle surfactants and often are included in products marketed as safe for sensitive skin,¹⁴ such as “free and gentle” detergents.⁸ However, they actually may pose an increased risk for sensitization in patients with atopic dermatitis.¹⁴ In addition to being allergenic, surfactants and emulsifiers are known irritants.^6,15 Although pathologically distinct, ACD and irritant contact dermatitis can be indistinguishable on clinical presentation.

How Commonly Does Laundry Detergent Cause ACD?

The mere presence of a contact allergen in laundry detergent does not necessarily imply that it is likely to cause ACD. To do so, the chemical in question must exceed the exposure thresholds for primary sensitization (ie, induction of contact allergy) and/or elicitation (ie, development of ACD in sensitized individuals). These depend on a complex interplay of product- and patient-specific factors, among them the concentration of the chemical in the detergent, the method of use, and the amount of detergent residue remaining on clothing after washing.

In the 1990s, the North American Contact Dermatitis Group (NACDG) attempted to determine the prevalence of ACD caused by laundry detergent.¹ Among 738 patients patch tested to aqueous dilutions of granular and liquid laundry detergents, only 5 (0.7%) had a possible allergic patch test reaction. It was unclear what the culprit allergens in the detergents may have been; only 1 of the patients also tested positive to fragrance. Two patients underwent further testing to additional detergent dilutions, and the results called into question whether their initial reactions had truly been allergic (positive) or were actually irritant (negative). The investigators concluded that the prevalence of laundry detergent–associated ACD in this large group of patients was at most 0.7%, and possibly lower.¹

Importantly, patch testing to laundry detergents should not be undertaken in routine clinical practice. Laundry detergents should never be tested “as is” (ie, undiluted) on the skin; they are inherently irritating and have a high likelihood of producing misleading false-positive reactions. Careful dilutions and testing of control subjects are necessary if patch testing with these products is to be appropriately conducted.

 

 

Isothiazolinones in Laundry Detergent

The extremely low prevalence of laundry detergent–associated ACD reported by the NACDG was determined prior to the start of the worldwide MI allergy epidemic, raising the possibility that laundry detergents containing isothiazolinones may be associated with ACD. There is no consensus about the minimum level at which isothiazolinones pose no risk to consumers,^16-19 but the US Expert Panel for Cosmetic Ingredient Safety declared that MI is “safe for use in rinse-off cosmetic products at concentrations up to 100 ppm and safe in leave-on cosmetic products when they are formulated to be nonsensitizing.”^18,19 Although ingredient lists do not always reveal when isothiazolinones are present, analyses of commercially available laundry detergents have shown MI concentrations ranging from undetectable to 65.7 ppm.^20-23

Published reports suggest that MCI/MI in laundry detergent can elicit ACD in sensitized individuals. In one case, a 7-year-old girl with chronic truncal dermatitis (atopic history unspecified) was patch tested, revealing a strongly positive reaction to MCI/MI.²⁴ Her laundry detergent was the only personal product found to contain MI. The dermatitis completely resolved after switching detergents and flared after wearing a jacket that had been washed in the implicated detergent, further supporting the relevance of the positive patch test. The investigators suspected initial sensitization to MI from wet wipes used earlier in childhood.²⁴ In another case involving occupational exposure, a 39-year-old nonatopic factory worker was responsible for directly adding MI to laundry detergent.²⁵ Although he wore disposable work gloves, he developed severe hand dermatitis, eczematous pretibial patches, and generalized pruritus. Patch testing revealed positive reactions to MCI/MI and MI, and he experienced improvement when reassigned to different work duties. It was hypothesized that the leg dermatitis and generalized pruritus may have been related to exposure to small concentrations of MI in work clothes washed with an MI-containing detergent.²⁵ Notably, this patient’s level of exposure was much greater than that encountered by individuals in day-to-day life outside of specialized occupational settings.

Regarding other isothiazolinones, a toxicologic study estimated that BIT in laundry detergent would be unlikely to induce sensitization, even at the maximal acceptable concentration, as recommended by preservative manufacturers, and accounting for undiluted detergent spilling directly onto the skin.²⁶ Nonetheless, a single European center recently reported that almost half of the 38 patients with positive patch tests to BIT had a potentially relevant exposure attributed to household cleaning products, including laundry detergent.¹³ This emphasizes the need for further examination of sources of exposure to this increasingly common positive patch test allergen.

Does Machine Washing Impact Allergen Concentrations?

Two recent investigations have suggested that machine washing reduces concentrations of isothiazolinones to levels that are likely below clinical relevance. In the first study, 3 fabrics—cotton, polyester, cotton-polyester—were machine washed and line dried.²⁷ A standard detergent was used with MI added at different concentrations: less than 1 ppm, 100 ppm, and 1000 ppm. This process was either performed once or 10 times. Following laundering and line drying, MI was undetectable in all fabrics regardless of MI concentration or number of times washed (detection limit, 0.5 ppm).²⁷ In the second study, 4 fabrics—cotton, wool, polyester, linen—were washed with standard laundry detergent in 1 of 4 ways: handwashing (positive control), standard machine washing, standard machine washing with fabric softener, and standard machine washing with a double rinse.²⁸ After laundering and line drying, concentrations of MI, MCI, and BIT were low or undetectable regardless of fabric type or method of laundering. The highest levels detected were in handwashed garments at a maximum of 0.5 ppm of MI. The study authors postulated that chemical concentrations near these maximum residual levels may pose a risk for eliciting ACD in highly sensitized individuals. Therefore, handwashing can be considered a much higher risk activity for isothiazolinone ACD compared with machine washing.²⁸

It is intriguing that machine washing appears to reduce isothiazolinones to low concentrations that may have limited likelihood of causing ACD. Similar findings have been reported regarding fragrances. A quantitative risk assessment performed on 24 of 26 fragrance allergens regulated by the European Union determined that the amount of fragrance deposited on the skin from laundered garments would be less than the threshold for causing sensitization.²⁹ Although this risk assessment was unable to address the threshold of elicitation, another study conducted in Europe investigated whether fragrance residues present on fabric, such as those deposited from laundry detergent, are present at high enough concentrations to elicit ACD in previously sensitized individuals.³⁰ When 36 individuals were patch tested with increasing concentrations of a fragrance to which they were already sensitized, only 2 (5.6%) had a weakly positive reaction and then only to the highest concentration, which was estimated to be 20-fold higher than the level of skin exposure after normal laundering. No patient reacted at lower concentrations.³⁰

Although machine washing may decrease isothiazolinone and/or fragrance concentrations in laundry detergent to below clinically relevant levels, these findings should not necessarily be extrapolated to all chemicals in laundry detergent. Indeed, a prior study observed that after washing cotton cloths in a detergent solution for 10 minutes, detergent residue was present at concentrations ranging from 139 to 2820 ppm and required a subsequent 20 to 22 washes in water to become undetectable.³¹ Another study produced a mathematical model of the residual concentration of sodium dodecyl sulphate (SDS), a surfactant and known irritant, in laundered clothing.³² It was estimated that after machine washing, the residual concentration of SDS on clothes would be too low to cause irritation; however, as the clothes dry (ie, as moisture evaporates but solutes remain), the concentration of SDS on the fabric’s surface would increase to potentially irritating levels. The extensive drying that is possible with electric dryers may further enhance this solute-concentrating effect.

Differential Diagnosis of Laundry Detergent ACD

The propensity for laundry detergent to cause ACD is a question that is nowhere near settled, but the prevalence of allergy likely is far less common than is generally suspected. In our experience, many patients presenting for patch testing have already made the change to “free and clear” detergents without noticeable improvement in their dermatitis, which could possibly relate to the ongoing presence of contact allergens in these “gentle” formulations.⁷ However, to avoid anchoring bias, more frequent causes of dermatitis should be included in the differential diagnosis. Textile ACD presents beneath clothing with accentuation at areas of closest contact with the skin, classically involving the axillary rim but sparing the vault. The most frequently implicated allergens in textile ACD are disperse dyes and less commonly textile resins.^33,34 Between 2017 and 2018, 2.3% of 4882 patients patch tested by the NACDG reacted positively to disperse dye mix.¹⁰ There is evidence to suggest that the actual prevalence of disperse dye allergy might be higher due to inadequacy of screening allergens on baseline patch test series.³⁵ Additional diagnoses that should be distinguished from presumed detergent contact dermatitis include atopic dermatitis and cutaneous T-cell lymphoma.

Final Interpretation

Although many patients and physicians consider laundry detergent to be a major cause of ACD, there is limited high-quality evidence to support this belief. Contact allergy to laundry detergent is probably much less common than is widely supposed. Although laundry detergents can contain common allergens such as fragrances and preservatives, evidence suggests that they are likely reduced to below clinically relevant levels during routine machine washing; however, we cannot assume that we are in the “free and clear,” as uncertainty remains about the impact of these low concentrationson individuals with strong contact allergy, and large studies of patch testing to modern detergents have yet to be carried out.

NEW ORLEANS – Among individuals who were surveyed at a health fair, most of whom were persons of color, 57% self-reported having sensitive skin.

Respondents also reported high rates of reactions to skin care products marketed for sensitive skin, and most said they had visited a dermatologist about their condition.

Those are among the key findings of a pilot study designed to assess the prevalence, symptom burden, and behaviors of self-identified persons of color with sensitive skin, which senior author Adam Friedman, MD, and colleagues defined as a subjective syndrome of cutaneous hyperreactivity to otherwise innocuous stimuli. “Improved understanding of sensitive skin is essential, and we encourage additional research into pathophysiology and creating a consensus definition for sensitive skin,” Dr. Friedman, professor and chair of dermatology at George Washington University, Washington, said in an interview in advance of the annual meeting of the American Academy of Dermatology, where the study was presented during an e-poster session. The findings were also reported online in JAAD International.

In May of 2022, Dr. Friedman, first author Erika McCormick, a 4th-year medical student at George Washington University, and colleagues invited individuals attending a community health fair in an undeserved area of Washington, to complete the Sensitive Scale-10 (SS-10) and to answer other questions after receiving a brief education about sensitive skin. Of the 58 respondents, 78% were female, and 86% self-identified as a person of color.

“Our study population predominantly self-identified as Black, which only represents one piece of those who would be characterized as persons of color,” Dr. Friedman said. “That said, improved representation of both our study population, and furthermore persons of color, in all aspects of dermatology research is crucial to at a minimum ensure generalizability of findings to the U.S. population, and research on sensitive skin is but one component of this.”

Nearly two-thirds of all respondents (63.8%) reported having an underlying skin condition, most commonly acne (21%), eczema (17%), and rosacea (6%). More than half (57%) reported sensitive skin, 27% of whom reported no other skin disease. Individuals with sensitive skin had higher mean SS-10 scores, compared with those with nonsensitive skin (14.61 vs. 4.32; P = .002) and burning was the main symptom among those with sensitive skin (56%), followed by itch (50%), redness (39%), dryness (39%) and pain (17%).

Compared with those who did not meet criteria for sensitive skin, those who did were more likely to report a personal history of allergy (56.25% vs. 8.33%; P = .0002) and were nearly seven times more likely to have seen a dermatologist about their concerns (odds ratio, 6.857; P = .0012).

In other findings limited to respondents with sensitive skin, 72% who reported reactions to general consumer skin care products also reported reacting to products marketed for sensitive skin, and 94% reported reactivity to at least one trigger, most commonly extreme temperatures (34%), stress (34%), sweat (33%), sun exposure (29%), and diet (28%). “We were particularly surprised by the high rates of reactivity to skin care products designed for and marketed to those suffering with sensitive skin,” Ms. McCormick told this news organization. “Importantly, there is currently no federal or legal standard regulating ingredients in products marketed for sensitive skin, and many products lack testing in sensitive skin specifically. Our data suggest an opportunity for improvement of sensitive skin care.”

She acknowledged certain limitations of the study, including its small sample size. “Reconducting this survey in a larger population will help validate our findings,” she said.

The research was supported by two independent research grants from Galderma: one supporting Ms. McCormick with a Sensitive Skin Research Fellowship and the other a Sensitive Skin Research Acceleration Fund. Dr. Friedman reported having no relevant disclosures.

NEW ORLEANS – Among individuals who were surveyed at a health fair, most of whom were persons of color, 57% self-reported having sensitive skin.

Respondents also reported high rates of reactions to skin care products marketed for sensitive skin, and most said they had visited a dermatologist about their condition.

Those are among the key findings of a pilot study designed to assess the prevalence, symptom burden, and behaviors of self-identified persons of color with sensitive skin, which senior author Adam Friedman, MD, and colleagues defined as a subjective syndrome of cutaneous hyperreactivity to otherwise innocuous stimuli. “Improved understanding of sensitive skin is essential, and we encourage additional research into pathophysiology and creating a consensus definition for sensitive skin,” Dr. Friedman, professor and chair of dermatology at George Washington University, Washington, said in an interview in advance of the annual meeting of the American Academy of Dermatology, where the study was presented during an e-poster session. The findings were also reported online in JAAD International.

In May of 2022, Dr. Friedman, first author Erika McCormick, a 4th-year medical student at George Washington University, and colleagues invited individuals attending a community health fair in an undeserved area of Washington, to complete the Sensitive Scale-10 (SS-10) and to answer other questions after receiving a brief education about sensitive skin. Of the 58 respondents, 78% were female, and 86% self-identified as a person of color.

“Our study population predominantly self-identified as Black, which only represents one piece of those who would be characterized as persons of color,” Dr. Friedman said. “That said, improved representation of both our study population, and furthermore persons of color, in all aspects of dermatology research is crucial to at a minimum ensure generalizability of findings to the U.S. population, and research on sensitive skin is but one component of this.”

Nearly two-thirds of all respondents (63.8%) reported having an underlying skin condition, most commonly acne (21%), eczema (17%), and rosacea (6%). More than half (57%) reported sensitive skin, 27% of whom reported no other skin disease. Individuals with sensitive skin had higher mean SS-10 scores, compared with those with nonsensitive skin (14.61 vs. 4.32; P = .002) and burning was the main symptom among those with sensitive skin (56%), followed by itch (50%), redness (39%), dryness (39%) and pain (17%).

Compared with those who did not meet criteria for sensitive skin, those who did were more likely to report a personal history of allergy (56.25% vs. 8.33%; P = .0002) and were nearly seven times more likely to have seen a dermatologist about their concerns (odds ratio, 6.857; P = .0012).

In other findings limited to respondents with sensitive skin, 72% who reported reactions to general consumer skin care products also reported reacting to products marketed for sensitive skin, and 94% reported reactivity to at least one trigger, most commonly extreme temperatures (34%), stress (34%), sweat (33%), sun exposure (29%), and diet (28%). “We were particularly surprised by the high rates of reactivity to skin care products designed for and marketed to those suffering with sensitive skin,” Ms. McCormick told this news organization. “Importantly, there is currently no federal or legal standard regulating ingredients in products marketed for sensitive skin, and many products lack testing in sensitive skin specifically. Our data suggest an opportunity for improvement of sensitive skin care.”

She acknowledged certain limitations of the study, including its small sample size. “Reconducting this survey in a larger population will help validate our findings,” she said.

The research was supported by two independent research grants from Galderma: one supporting Ms. McCormick with a Sensitive Skin Research Fellowship and the other a Sensitive Skin Research Acceleration Fund. Dr. Friedman reported having no relevant disclosures.

NEW ORLEANS – Among individuals who were surveyed at a health fair, most of whom were persons of color, 57% self-reported having sensitive skin.

Respondents also reported high rates of reactions to skin care products marketed for sensitive skin, and most said they had visited a dermatologist about their condition.

Those are among the key findings of a pilot study designed to assess the prevalence, symptom burden, and behaviors of self-identified persons of color with sensitive skin, which senior author Adam Friedman, MD, and colleagues defined as a subjective syndrome of cutaneous hyperreactivity to otherwise innocuous stimuli. “Improved understanding of sensitive skin is essential, and we encourage additional research into pathophysiology and creating a consensus definition for sensitive skin,” Dr. Friedman, professor and chair of dermatology at George Washington University, Washington, said in an interview in advance of the annual meeting of the American Academy of Dermatology, where the study was presented during an e-poster session. The findings were also reported online in JAAD International.

In May of 2022, Dr. Friedman, first author Erika McCormick, a 4th-year medical student at George Washington University, and colleagues invited individuals attending a community health fair in an undeserved area of Washington, to complete the Sensitive Scale-10 (SS-10) and to answer other questions after receiving a brief education about sensitive skin. Of the 58 respondents, 78% were female, and 86% self-identified as a person of color.

“Our study population predominantly self-identified as Black, which only represents one piece of those who would be characterized as persons of color,” Dr. Friedman said. “That said, improved representation of both our study population, and furthermore persons of color, in all aspects of dermatology research is crucial to at a minimum ensure generalizability of findings to the U.S. population, and research on sensitive skin is but one component of this.”

Nearly two-thirds of all respondents (63.8%) reported having an underlying skin condition, most commonly acne (21%), eczema (17%), and rosacea (6%). More than half (57%) reported sensitive skin, 27% of whom reported no other skin disease. Individuals with sensitive skin had higher mean SS-10 scores, compared with those with nonsensitive skin (14.61 vs. 4.32; P = .002) and burning was the main symptom among those with sensitive skin (56%), followed by itch (50%), redness (39%), dryness (39%) and pain (17%).

Compared with those who did not meet criteria for sensitive skin, those who did were more likely to report a personal history of allergy (56.25% vs. 8.33%; P = .0002) and were nearly seven times more likely to have seen a dermatologist about their concerns (odds ratio, 6.857; P = .0012).

In other findings limited to respondents with sensitive skin, 72% who reported reactions to general consumer skin care products also reported reacting to products marketed for sensitive skin, and 94% reported reactivity to at least one trigger, most commonly extreme temperatures (34%), stress (34%), sweat (33%), sun exposure (29%), and diet (28%). “We were particularly surprised by the high rates of reactivity to skin care products designed for and marketed to those suffering with sensitive skin,” Ms. McCormick told this news organization. “Importantly, there is currently no federal or legal standard regulating ingredients in products marketed for sensitive skin, and many products lack testing in sensitive skin specifically. Our data suggest an opportunity for improvement of sensitive skin care.”

She acknowledged certain limitations of the study, including its small sample size. “Reconducting this survey in a larger population will help validate our findings,” she said.

The research was supported by two independent research grants from Galderma: one supporting Ms. McCormick with a Sensitive Skin Research Fellowship and the other a Sensitive Skin Research Acceleration Fund. Dr. Friedman reported having no relevant disclosures.

The Diagnosis: Allergic Contact Dermatitis

This patient’s history and physical examination were most consistent with a diagnosis of allergic contact dermatitis, likely from an additive or diluent solution within the tattoo ink. Her history of a similar transient reaction following tattooing 2 weeks prior lent credence to an allergic etiology. She was treated with triamcinolone cream 0.1% as well as mupirocin ointment 2% for use as both an emollient and for precautionary antimicrobial coverage. The rash resolved within 2 days, and she reported no recurrence at a 6-month follow-up. The cosmesis of her tattoo was preserved.

Acute cellulitis may follow tattooing, but the absence of warmth, pain, or purulence on physical examination made this diagnosis less likely in this patient. Sarcoidosis or other granulomatous reactions may present as papules or nodules arising within a tattoo but would be unlikely to occur the next day. Nontuberculous mycobacterial infection likewise tends to present subacutely or chronically rather than immediately following tattoo application.

Tattooing has existed for millennia and is becoming increasingly popular.^1,2 The tattooing process entails introduction of insoluble pigment compounds into the dermis to create a permanent design on the skin, which most often is accomplished via needling. As a result, tattooed skin is susceptible to both acute and chronic complications. Acute complications prominently include allergic hypersensitivity reactions and pyogenic bacterial infections. Chronic granulomatous, inflammatory, or infectious complications also can occur.

Allergic eczematous reactions to tattooing are well documented in the literature and are thought to originate from sensitization to pigment molecules themselves or alternatively to ink diluent compounds.³ Although reactions to ink diluent chemicals typically are self-resolving, allergic reactions to pigment can persist beyond the acute phase, as these insoluble compounds intentionally remain embedded in the dermis. The mechanism of action may involve haptenization of pigment molecules that then induces allergic hypersensitivity.^3,4 Black pigment typically is derived from carbon black (ie, amorphous combustion byproducts such as soot). Colored inks historically consisted of inorganic heavy metal–containing salts prior to the modern introduction of synthetic azo and polycyclic dyes. These newer colored pigments appear to be less allergenic than their metallic predecessors; however, epidemiologic studies have suggested that allergic reactions still occur more commonly in colored tattoos than black tattoos.¹ Overall, these reactions may occur in as many as one-third of individuals who receive tattoos.^2,4

As with any process that disrupts skin integrity, tattooing carries a risk for transmitting various infectious pathogens. Microbes may originate from adjacent skin, contaminated needles, ink bottles, or nonsterile ink diluents. Although tattoo parlors and artists may undergo licensing to demonstrate adherence to hygienic standards, regulations vary between states and do not include testing of ink or ink additives to ensure sterility.^4,5 Staphylococci and streptococci commonly are implicated in acute pyogenic skin infections following tattooing.^5,6 Nontuberculous mycobacteria increasingly are being recognized as causative organisms for granulomatous lesions developing subacutely or even months after receiving a new tattoo.^5,7 Local and systemic viral infections also may be transmitted during tattooing; cases of tattoo-transmitted viral warts, molluscum contagiosum, and hepatitis B and C viruses all have been observed.^5,6,8 Herpes simplex virus transmission (colloquially termed herpes compunctorum) and HIV transmission through tattooing also are hypothesized to be possible, though there is a paucity of known cases for each.^8,9

Chronic inflammatory, granulomatous, or neoplastic lesions may arise within tattooed skin months or years after tattooing. Foreign body granulomas, sarcoidosis, pseudolymphoma, pseudoepitheliomatous hyperplasia, and keratoacanthoma are some representative entities.^3,5 Cases of cancerous lesions in tattooed skin have been documented, but their incidence appears similar to nontattooed skin.³ These broad categories of lesions are clinically diverse but may be difficult to definitively diagnose on examination alone; therefore, a biopsy should be strongly considered for any subacute to chronic skin lesions within a tattoo. Patients may be hesitant to disrupt the cosmesis of a tattoo but should be counseled on the attendant risks and benefits to make an informed decision regarding biopsy.

The Diagnosis: Allergic Contact Dermatitis

This patient’s history and physical examination were most consistent with a diagnosis of allergic contact dermatitis, likely from an additive or diluent solution within the tattoo ink. Her history of a similar transient reaction following tattooing 2 weeks prior lent credence to an allergic etiology. She was treated with triamcinolone cream 0.1% as well as mupirocin ointment 2% for use as both an emollient and for precautionary antimicrobial coverage. The rash resolved within 2 days, and she reported no recurrence at a 6-month follow-up. The cosmesis of her tattoo was preserved.

Acute cellulitis may follow tattooing, but the absence of warmth, pain, or purulence on physical examination made this diagnosis less likely in this patient. Sarcoidosis or other granulomatous reactions may present as papules or nodules arising within a tattoo but would be unlikely to occur the next day. Nontuberculous mycobacterial infection likewise tends to present subacutely or chronically rather than immediately following tattoo application.

Tattooing has existed for millennia and is becoming increasingly popular.^1,2 The tattooing process entails introduction of insoluble pigment compounds into the dermis to create a permanent design on the skin, which most often is accomplished via needling. As a result, tattooed skin is susceptible to both acute and chronic complications. Acute complications prominently include allergic hypersensitivity reactions and pyogenic bacterial infections. Chronic granulomatous, inflammatory, or infectious complications also can occur.

Allergic eczematous reactions to tattooing are well documented in the literature and are thought to originate from sensitization to pigment molecules themselves or alternatively to ink diluent compounds.³ Although reactions to ink diluent chemicals typically are self-resolving, allergic reactions to pigment can persist beyond the acute phase, as these insoluble compounds intentionally remain embedded in the dermis. The mechanism of action may involve haptenization of pigment molecules that then induces allergic hypersensitivity.^3,4 Black pigment typically is derived from carbon black (ie, amorphous combustion byproducts such as soot). Colored inks historically consisted of inorganic heavy metal–containing salts prior to the modern introduction of synthetic azo and polycyclic dyes. These newer colored pigments appear to be less allergenic than their metallic predecessors; however, epidemiologic studies have suggested that allergic reactions still occur more commonly in colored tattoos than black tattoos.¹ Overall, these reactions may occur in as many as one-third of individuals who receive tattoos.^2,4

As with any process that disrupts skin integrity, tattooing carries a risk for transmitting various infectious pathogens. Microbes may originate from adjacent skin, contaminated needles, ink bottles, or nonsterile ink diluents. Although tattoo parlors and artists may undergo licensing to demonstrate adherence to hygienic standards, regulations vary between states and do not include testing of ink or ink additives to ensure sterility.^4,5 Staphylococci and streptococci commonly are implicated in acute pyogenic skin infections following tattooing.^5,6 Nontuberculous mycobacteria increasingly are being recognized as causative organisms for granulomatous lesions developing subacutely or even months after receiving a new tattoo.^5,7 Local and systemic viral infections also may be transmitted during tattooing; cases of tattoo-transmitted viral warts, molluscum contagiosum, and hepatitis B and C viruses all have been observed.^5,6,8 Herpes simplex virus transmission (colloquially termed herpes compunctorum) and HIV transmission through tattooing also are hypothesized to be possible, though there is a paucity of known cases for each.^8,9

Chronic inflammatory, granulomatous, or neoplastic lesions may arise within tattooed skin months or years after tattooing. Foreign body granulomas, sarcoidosis, pseudolymphoma, pseudoepitheliomatous hyperplasia, and keratoacanthoma are some representative entities.^3,5 Cases of cancerous lesions in tattooed skin have been documented, but their incidence appears similar to nontattooed skin.³ These broad categories of lesions are clinically diverse but may be difficult to definitively diagnose on examination alone; therefore, a biopsy should be strongly considered for any subacute to chronic skin lesions within a tattoo. Patients may be hesitant to disrupt the cosmesis of a tattoo but should be counseled on the attendant risks and benefits to make an informed decision regarding biopsy.

The Diagnosis: Allergic Contact Dermatitis

This patient’s history and physical examination were most consistent with a diagnosis of allergic contact dermatitis, likely from an additive or diluent solution within the tattoo ink. Her history of a similar transient reaction following tattooing 2 weeks prior lent credence to an allergic etiology. She was treated with triamcinolone cream 0.1% as well as mupirocin ointment 2% for use as both an emollient and for precautionary antimicrobial coverage. The rash resolved within 2 days, and she reported no recurrence at a 6-month follow-up. The cosmesis of her tattoo was preserved.

Acute cellulitis may follow tattooing, but the absence of warmth, pain, or purulence on physical examination made this diagnosis less likely in this patient. Sarcoidosis or other granulomatous reactions may present as papules or nodules arising within a tattoo but would be unlikely to occur the next day. Nontuberculous mycobacterial infection likewise tends to present subacutely or chronically rather than immediately following tattoo application.

Tattooing has existed for millennia and is becoming increasingly popular.^1,2 The tattooing process entails introduction of insoluble pigment compounds into the dermis to create a permanent design on the skin, which most often is accomplished via needling. As a result, tattooed skin is susceptible to both acute and chronic complications. Acute complications prominently include allergic hypersensitivity reactions and pyogenic bacterial infections. Chronic granulomatous, inflammatory, or infectious complications also can occur.

Allergic eczematous reactions to tattooing are well documented in the literature and are thought to originate from sensitization to pigment molecules themselves or alternatively to ink diluent compounds.³ Although reactions to ink diluent chemicals typically are self-resolving, allergic reactions to pigment can persist beyond the acute phase, as these insoluble compounds intentionally remain embedded in the dermis. The mechanism of action may involve haptenization of pigment molecules that then induces allergic hypersensitivity.^3,4 Black pigment typically is derived from carbon black (ie, amorphous combustion byproducts such as soot). Colored inks historically consisted of inorganic heavy metal–containing salts prior to the modern introduction of synthetic azo and polycyclic dyes. These newer colored pigments appear to be less allergenic than their metallic predecessors; however, epidemiologic studies have suggested that allergic reactions still occur more commonly in colored tattoos than black tattoos.¹ Overall, these reactions may occur in as many as one-third of individuals who receive tattoos.^2,4

As with any process that disrupts skin integrity, tattooing carries a risk for transmitting various infectious pathogens. Microbes may originate from adjacent skin, contaminated needles, ink bottles, or nonsterile ink diluents. Although tattoo parlors and artists may undergo licensing to demonstrate adherence to hygienic standards, regulations vary between states and do not include testing of ink or ink additives to ensure sterility.^4,5 Staphylococci and streptococci commonly are implicated in acute pyogenic skin infections following tattooing.^5,6 Nontuberculous mycobacteria increasingly are being recognized as causative organisms for granulomatous lesions developing subacutely or even months after receiving a new tattoo.^5,7 Local and systemic viral infections also may be transmitted during tattooing; cases of tattoo-transmitted viral warts, molluscum contagiosum, and hepatitis B and C viruses all have been observed.^5,6,8 Herpes simplex virus transmission (colloquially termed herpes compunctorum) and HIV transmission through tattooing also are hypothesized to be possible, though there is a paucity of known cases for each.^8,9

Chronic inflammatory, granulomatous, or neoplastic lesions may arise within tattooed skin months or years after tattooing. Foreign body granulomas, sarcoidosis, pseudolymphoma, pseudoepitheliomatous hyperplasia, and keratoacanthoma are some representative entities.^3,5 Cases of cancerous lesions in tattooed skin have been documented, but their incidence appears similar to nontattooed skin.³ These broad categories of lesions are clinically diverse but may be difficult to definitively diagnose on examination alone; therefore, a biopsy should be strongly considered for any subacute to chronic skin lesions within a tattoo. Patients may be hesitant to disrupt the cosmesis of a tattoo but should be counseled on the attendant risks and benefits to make an informed decision regarding biopsy.

Lanolin, known mainly for its emollient properties, has been named by the American Contact Dermatitis Society as the Contact Allergen of the Year for 2023.

Lanolin is a complex and varying mixture of high molecular weight esters, aliphatic alcohols, sterols, fatty acids, and hydrocarbons, but the allergic components are mainly the free lanolin alcohols, especially alkanediols, said Donald V. Belsito, MD, professor of dermatology, Columbia University, New York, who announced the Allergen of the Year at the society’s annual meeting.

Criteria for selection can include a known allergen with a new twist or increasing frequency or a newly reported allergen with mini-epidemics that may have been missed for years, Dr. Belsito said.

“The prevalence and severity of allergy to ‘lanolin’ have been hotly debated” since a potential case was first reported in the 1920s, wrote Dr. Belsito and Blair A. Jenkins, MD, PhD, a dermatology resident at New York–Presbyterian Hospital, Columbia Campus, in a review published in Dermatitis.

“ ‘Lanolin’ is indeed a paradox allergen,” wrote Dr. Jenkins and Dr. Belsito. “The most appropriate patch test preparation(s) for detecting allergy remain disputed. Detection of lanolin-induced contact dermatitis in diseased skin by patch testing on normal skin may lead to false negative results.”

And those who test positive for a lanolin allergy on diseased skin may be able to use lanolin products on normal skin, they wrote.

“From my perspective, this was a timely year to think about lanolin, as there is significant ongoing controversy about whether it is allergenic,” Dr. Jenkins said in an interview. “Numerous companies market lanolin-containing topicals as safe and effective emollients,” she said.
 

Medical grade and highly purified anhydrous lanolin, which contain less than 2.5% and less than 1.5% of free alcohols, respectively, can still elicit or induce a contact allergy, Dr. Belsito said in his presentation. Hydrogenated lanolin has shown more allergenicity than lanolin alcohol, while lanolin wax, lanolin acid, and lanolin esters possess lower allergenicity than lanolin alcohol, he said.

Notably, modern wool textiles do not contain lanolin, and lanolin-allergic patients need not avoid wool, Dr. Belsito added.

Amerchol L-101, a common trade name on products containing lanolin, contains 10% wool wax alcohols obtained from the hydrolysis of wool fat dissolved in mineral oil at a 1:1 ratio, said Dr. Belsito. He recommended testing lanolin alcohols (in 30% petrolatum) and Amerchol L-101 (in 50% petrolatum) simultaneously with or without other lanolin derivatives and/or the patient’s products in cases of possible allergy, he said.
 

Consider high-risk groups

Current evidence suggests that the prevalence of contact allergy in the western European population is 0.4%, wrote Dr. Jenkins and Dr. Belsito.

Although the frequency of lanolin allergy is relatively low, certain conditions convey greater risk, such as stasis dermatitis, leg ulcers, perianal/genital dermatitis, and atopic dermatitis, they wrote. Older adults and children are at increased risk because they are more likely to have these conditions. Demographic data also suggest that lanolin allergy is more common in non-Hispanic Whites than in non-Hispanic Blacks, they wrote.

Looking ahead, “I think further exploration of allergy across different skin types and ethnicities is warranted,” Dr. Jenkins said. “Further investigation of ideal [lanolin] allergens for patch testing is also needed.”

Dr. Jenkins and Dr. Belsito said they had no relevant financial conflicts to disclose.

Lanolin, known mainly for its emollient properties, has been named by the American Contact Dermatitis Society as the Contact Allergen of the Year for 2023.

Lanolin is a complex and varying mixture of high molecular weight esters, aliphatic alcohols, sterols, fatty acids, and hydrocarbons, but the allergic components are mainly the free lanolin alcohols, especially alkanediols, said Donald V. Belsito, MD, professor of dermatology, Columbia University, New York, who announced the Allergen of the Year at the society’s annual meeting.

Criteria for selection can include a known allergen with a new twist or increasing frequency or a newly reported allergen with mini-epidemics that may have been missed for years, Dr. Belsito said.

“The prevalence and severity of allergy to ‘lanolin’ have been hotly debated” since a potential case was first reported in the 1920s, wrote Dr. Belsito and Blair A. Jenkins, MD, PhD, a dermatology resident at New York–Presbyterian Hospital, Columbia Campus, in a review published in Dermatitis.

“ ‘Lanolin’ is indeed a paradox allergen,” wrote Dr. Jenkins and Dr. Belsito. “The most appropriate patch test preparation(s) for detecting allergy remain disputed. Detection of lanolin-induced contact dermatitis in diseased skin by patch testing on normal skin may lead to false negative results.”

And those who test positive for a lanolin allergy on diseased skin may be able to use lanolin products on normal skin, they wrote.

“From my perspective, this was a timely year to think about lanolin, as there is significant ongoing controversy about whether it is allergenic,” Dr. Jenkins said in an interview. “Numerous companies market lanolin-containing topicals as safe and effective emollients,” she said.
 

Medical grade and highly purified anhydrous lanolin, which contain less than 2.5% and less than 1.5% of free alcohols, respectively, can still elicit or induce a contact allergy, Dr. Belsito said in his presentation. Hydrogenated lanolin has shown more allergenicity than lanolin alcohol, while lanolin wax, lanolin acid, and lanolin esters possess lower allergenicity than lanolin alcohol, he said.

Notably, modern wool textiles do not contain lanolin, and lanolin-allergic patients need not avoid wool, Dr. Belsito added.

Amerchol L-101, a common trade name on products containing lanolin, contains 10% wool wax alcohols obtained from the hydrolysis of wool fat dissolved in mineral oil at a 1:1 ratio, said Dr. Belsito. He recommended testing lanolin alcohols (in 30% petrolatum) and Amerchol L-101 (in 50% petrolatum) simultaneously with or without other lanolin derivatives and/or the patient’s products in cases of possible allergy, he said.
 

Consider high-risk groups

Current evidence suggests that the prevalence of contact allergy in the western European population is 0.4%, wrote Dr. Jenkins and Dr. Belsito.

Although the frequency of lanolin allergy is relatively low, certain conditions convey greater risk, such as stasis dermatitis, leg ulcers, perianal/genital dermatitis, and atopic dermatitis, they wrote. Older adults and children are at increased risk because they are more likely to have these conditions. Demographic data also suggest that lanolin allergy is more common in non-Hispanic Whites than in non-Hispanic Blacks, they wrote.

Looking ahead, “I think further exploration of allergy across different skin types and ethnicities is warranted,” Dr. Jenkins said. “Further investigation of ideal [lanolin] allergens for patch testing is also needed.”

Dr. Jenkins and Dr. Belsito said they had no relevant financial conflicts to disclose.

Lanolin, known mainly for its emollient properties, has been named by the American Contact Dermatitis Society as the Contact Allergen of the Year for 2023.

Lanolin is a complex and varying mixture of high molecular weight esters, aliphatic alcohols, sterols, fatty acids, and hydrocarbons, but the allergic components are mainly the free lanolin alcohols, especially alkanediols, said Donald V. Belsito, MD, professor of dermatology, Columbia University, New York, who announced the Allergen of the Year at the society’s annual meeting.

Criteria for selection can include a known allergen with a new twist or increasing frequency or a newly reported allergen with mini-epidemics that may have been missed for years, Dr. Belsito said.

“The prevalence and severity of allergy to ‘lanolin’ have been hotly debated” since a potential case was first reported in the 1920s, wrote Dr. Belsito and Blair A. Jenkins, MD, PhD, a dermatology resident at New York–Presbyterian Hospital, Columbia Campus, in a review published in Dermatitis.

“ ‘Lanolin’ is indeed a paradox allergen,” wrote Dr. Jenkins and Dr. Belsito. “The most appropriate patch test preparation(s) for detecting allergy remain disputed. Detection of lanolin-induced contact dermatitis in diseased skin by patch testing on normal skin may lead to false negative results.”

And those who test positive for a lanolin allergy on diseased skin may be able to use lanolin products on normal skin, they wrote.

“From my perspective, this was a timely year to think about lanolin, as there is significant ongoing controversy about whether it is allergenic,” Dr. Jenkins said in an interview. “Numerous companies market lanolin-containing topicals as safe and effective emollients,” she said.
 

Medical grade and highly purified anhydrous lanolin, which contain less than 2.5% and less than 1.5% of free alcohols, respectively, can still elicit or induce a contact allergy, Dr. Belsito said in his presentation. Hydrogenated lanolin has shown more allergenicity than lanolin alcohol, while lanolin wax, lanolin acid, and lanolin esters possess lower allergenicity than lanolin alcohol, he said.

Notably, modern wool textiles do not contain lanolin, and lanolin-allergic patients need not avoid wool, Dr. Belsito added.

Amerchol L-101, a common trade name on products containing lanolin, contains 10% wool wax alcohols obtained from the hydrolysis of wool fat dissolved in mineral oil at a 1:1 ratio, said Dr. Belsito. He recommended testing lanolin alcohols (in 30% petrolatum) and Amerchol L-101 (in 50% petrolatum) simultaneously with or without other lanolin derivatives and/or the patient’s products in cases of possible allergy, he said.
 

Consider high-risk groups

Current evidence suggests that the prevalence of contact allergy in the western European population is 0.4%, wrote Dr. Jenkins and Dr. Belsito.

Although the frequency of lanolin allergy is relatively low, certain conditions convey greater risk, such as stasis dermatitis, leg ulcers, perianal/genital dermatitis, and atopic dermatitis, they wrote. Older adults and children are at increased risk because they are more likely to have these conditions. Demographic data also suggest that lanolin allergy is more common in non-Hispanic Whites than in non-Hispanic Blacks, they wrote.

Looking ahead, “I think further exploration of allergy across different skin types and ethnicities is warranted,” Dr. Jenkins said. “Further investigation of ideal [lanolin] allergens for patch testing is also needed.”

Dr. Jenkins and Dr. Belsito said they had no relevant financial conflicts to disclose.

Josh struggled for more than a decade with what his doctors had told him was irritable bowel syndrome (IBS). But curiously, the 39-year-old’s flare-ups were caused by some foods that aren’t typical IBS triggers. Peanuts and shellfish caused “stabbing” abdominal pains, and he would feel lightheaded after simply inhaling the scent of them. He also had severe constipation that lasted up to a week and rectal mucous discharges.

So, Josh (not his real name) sought the care of New York gastroenterologist Yevgenia Pashinsky, MD. She conducted a comprehensive nutritional assessment and sent him for allergy testing. The results: Josh had a little-known condition called systemic nickel allergy syndrome (SNAS), which can mimic some of the symptoms of IBS.

Dr. Pashinsky, of the department of medicine at Icahn School of Medicine at Mount Sinai, New York, and a partner with New York Gastroenterology Associates, presented Josh’s case as part of a seminar on SNAS and IBS “mimickers” at the Food and Nutrition Conference and Expo in Orlando last October, sponsored by the Academy of Nutrition and Dietetics.

She and two registered dietitians in her practice, Suzie Finkel, MS, RD, CDN, and Tamara Duker Freuman, MS, RD, CDN, told seminar attendees that SNAS is rarely diagnosed and can be mistaken for IBS. They noted that it probably strikes more people than doctors suspect.

“Systemic nickel allergy is present in at least 10% of the U.S. population (and much higher in some subgroups),” Dr. Pashinsky told this news organization. “But its connection to GI symptoms and functional GI disorders is still being learned about.

“I think of nickel allergy and other allergic disorders when, in addition to GI symptoms, the patient reports skin and mucous membrane involvement along with their abdominal reactions,” she said.

For patients like Josh with SNAS, the diagnosis and treatment of this condition are surprisingly simple and effective.

“Josh had these really [unusual] symptoms and nontraditional IBS food triggers,” Ms. Finkel said in an interview. “So, that’s a situation where, as dietitians we say, ‘Hmm, that’s weird; if you have IBS, then peanuts and shrimp shouldn’t really cause an issue here.’ But this might be something physicians might not be attuned to because it’s not part of their training.”

Ms. Finkel said that Josh was referred to an allergist. Josh tested positive for skin sensitization to nickel, and he was started on a low-nickel diet, which improved his symptoms.

“So, that was this happy ending,” she added.

The upshot?

“Doctors who treat IBS patients [who are not responding to treatment] need to consider the possibility that they have SNAS and send them for allergy testing,” Ms. Finkel said. “If they come back positive, simple dietary changes can address it.”
 

An underrecognized condition

There has been very little research regarding SNAS in patients with IBS, and there are no standard guidelines for diagnosing and treating it.

What’s more, many gastroenterologists aren’t familiar with it. More than a dozen gastroenterologists who were contacted for comment declined to be interviewed because they didn’t know about SNAS – or enough about it to provide useful information for the story.

Ms. Finkel said she’s not surprised that many gastroenterologists don’t know much about how SNAS can mimic IBS, which is why she and her colleagues presented the seminar last October in Orlando. “It’s really an allergy and not a GI disease. It manifests with GI symptoms, but the root is not in the digestive tract; the root is in a true allergy – a clinical allergy – to nickel.”

Complicating the issue is that people who have IBS and those with SNAS typically share some common symptoms.

Like IBS, SNAS can cause GI symptoms – such as cramping, abdominal pain, heartburn, constipation, gaseous distension, and mucus in the stool. It can be triggered by certain fresh, cooked, and canned foods.

But the food triggers that cause SNAS are not usually those that cause IBS symptoms. Rather, SNAS flare-ups are nearly always triggered by foods with high levels of nickel. Examples include apricots, artichokes, asparagus, beans, cauliflower, chickpeas, cocoa/chocolate, figs, lentils, licorice, oats, onions, peas, peanuts, potatoes, spinach, tomatoes, and tea.

According to the American Academy of Allergy, Asthma & Immunology, a distinguishing feature of SNAS is that it can cause allergic contact dermatitis when a person touches something made with nickel. Coins, jewelry, eyeglasses, home fixtures, keys, zippers, dental devices, and even stainless-steel cookware can contain allergy-triggering nickel.

What Ms. Finkel sees the most are skin reactions from touching a surface containing nickel or from ingesting it, she said.

The other immediate symptom is abdominal pain or changes in bowel movements, such as diarrhea, she added.

Christopher Randolph, MD, an allergist based in Connecticut, told this news organization that it’s important for doctors to realize that patients who have a skin reaction to nickel may also have inflammatory GI symptoms.

“We definitely need more controlled studies,” said Dr. Randolph, of the department of allergy and immunology at Yale University, New Haven, Conn. “But the takeaway here is for patients and certainly providers to be mindful that you can have systemic reactions to nickel, even though you implicate only the contact dermatitis.”
 

Diagnosis and treatment recommendations

Skin patch allergy testing – in which a person’s skin is exposed to nickel – can quickly determine whether a patient with IBS is actually experiencing inflammatory reactions to dietary nickel and would benefit from a low-nickel or no-nickel diet, research shows.

For these patients, Dr. Pashinsky recommends the following:

• Avoiding high-nickel foods.
• Limiting canned foods.
• Using nonstainless cookware, especially for acidic foods.
• Boiling foods for potential nickel reduction, especially grains and vegetables.
• Running the tap before using water to drink or cook with first thing in the morning.

Dr. Pashisky and her team also recommend the following guidelines for doctors:

• Ask patients if symptoms occur immediately after eating certain high-nickel foods or worsen with a low-FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) diet.
• Determine whether a patient is not responding to typical medical and dietary interventions used to treat IBS.
• Conduct a food/symptom history to identify potential nickel allergy triggers.
• Try a low-nickel dietary intervention to see whether a patient’s symptoms improve in a week or two.
• Refer the patient for additional diagnostic skin-patch testing or treatment.

A multidisciplinary approach

Ms. Finkel said it’s important for doctors, particularly gastroenterologists who treat patients for suspected GI disorders to consider nickel allergy as a cause.

“SNAS is this overlooked condition ... and the research is really in its nascency here,” Ms. Finkel said.

“I would say only give [a low- or no-nickel diet] consideration if the high-nickel foods are a possible trigger,” she said. “It is very specific, looking at their diet history, to have a clear hypothesis based on what their triggers are. It’s not something to try out lightly because it’s a very restrictive diet, so I would never put a patient on a diet that I didn’t think was necessary.”

Ms. Finkel added that treatment of SNAS requires a multidisciplinary approach with a gastroenterologist, an allergist, and a dietitian.

Doctors and dietitians have distinct roles in identifying and treating these patients, Ms. Finkel said.

“If there is a suspicion of IBS symptoms and the patient is not responding to first-line treatments, then it is worth having the input of a dietitian and an allergist,” she said.

A version of this article first appeared on Medscape.com.

Josh struggled for more than a decade with what his doctors had told him was irritable bowel syndrome (IBS). But curiously, the 39-year-old’s flare-ups were caused by some foods that aren’t typical IBS triggers. Peanuts and shellfish caused “stabbing” abdominal pains, and he would feel lightheaded after simply inhaling the scent of them. He also had severe constipation that lasted up to a week and rectal mucous discharges.

So, Josh (not his real name) sought the care of New York gastroenterologist Yevgenia Pashinsky, MD. She conducted a comprehensive nutritional assessment and sent him for allergy testing. The results: Josh had a little-known condition called systemic nickel allergy syndrome (SNAS), which can mimic some of the symptoms of IBS.

Dr. Pashinsky, of the department of medicine at Icahn School of Medicine at Mount Sinai, New York, and a partner with New York Gastroenterology Associates, presented Josh’s case as part of a seminar on SNAS and IBS “mimickers” at the Food and Nutrition Conference and Expo in Orlando last October, sponsored by the Academy of Nutrition and Dietetics.

She and two registered dietitians in her practice, Suzie Finkel, MS, RD, CDN, and Tamara Duker Freuman, MS, RD, CDN, told seminar attendees that SNAS is rarely diagnosed and can be mistaken for IBS. They noted that it probably strikes more people than doctors suspect.

“Systemic nickel allergy is present in at least 10% of the U.S. population (and much higher in some subgroups),” Dr. Pashinsky told this news organization. “But its connection to GI symptoms and functional GI disorders is still being learned about.

“I think of nickel allergy and other allergic disorders when, in addition to GI symptoms, the patient reports skin and mucous membrane involvement along with their abdominal reactions,” she said.

For patients like Josh with SNAS, the diagnosis and treatment of this condition are surprisingly simple and effective.

“Josh had these really [unusual] symptoms and nontraditional IBS food triggers,” Ms. Finkel said in an interview. “So, that’s a situation where, as dietitians we say, ‘Hmm, that’s weird; if you have IBS, then peanuts and shrimp shouldn’t really cause an issue here.’ But this might be something physicians might not be attuned to because it’s not part of their training.”

Ms. Finkel said that Josh was referred to an allergist. Josh tested positive for skin sensitization to nickel, and he was started on a low-nickel diet, which improved his symptoms.

“So, that was this happy ending,” she added.

The upshot?

“Doctors who treat IBS patients [who are not responding to treatment] need to consider the possibility that they have SNAS and send them for allergy testing,” Ms. Finkel said. “If they come back positive, simple dietary changes can address it.”
 

An underrecognized condition

There has been very little research regarding SNAS in patients with IBS, and there are no standard guidelines for diagnosing and treating it.

What’s more, many gastroenterologists aren’t familiar with it. More than a dozen gastroenterologists who were contacted for comment declined to be interviewed because they didn’t know about SNAS – or enough about it to provide useful information for the story.

Ms. Finkel said she’s not surprised that many gastroenterologists don’t know much about how SNAS can mimic IBS, which is why she and her colleagues presented the seminar last October in Orlando. “It’s really an allergy and not a GI disease. It manifests with GI symptoms, but the root is not in the digestive tract; the root is in a true allergy – a clinical allergy – to nickel.”

Complicating the issue is that people who have IBS and those with SNAS typically share some common symptoms.

Like IBS, SNAS can cause GI symptoms – such as cramping, abdominal pain, heartburn, constipation, gaseous distension, and mucus in the stool. It can be triggered by certain fresh, cooked, and canned foods.

But the food triggers that cause SNAS are not usually those that cause IBS symptoms. Rather, SNAS flare-ups are nearly always triggered by foods with high levels of nickel. Examples include apricots, artichokes, asparagus, beans, cauliflower, chickpeas, cocoa/chocolate, figs, lentils, licorice, oats, onions, peas, peanuts, potatoes, spinach, tomatoes, and tea.

According to the American Academy of Allergy, Asthma & Immunology, a distinguishing feature of SNAS is that it can cause allergic contact dermatitis when a person touches something made with nickel. Coins, jewelry, eyeglasses, home fixtures, keys, zippers, dental devices, and even stainless-steel cookware can contain allergy-triggering nickel.

What Ms. Finkel sees the most are skin reactions from touching a surface containing nickel or from ingesting it, she said.

The other immediate symptom is abdominal pain or changes in bowel movements, such as diarrhea, she added.

Christopher Randolph, MD, an allergist based in Connecticut, told this news organization that it’s important for doctors to realize that patients who have a skin reaction to nickel may also have inflammatory GI symptoms.

“We definitely need more controlled studies,” said Dr. Randolph, of the department of allergy and immunology at Yale University, New Haven, Conn. “But the takeaway here is for patients and certainly providers to be mindful that you can have systemic reactions to nickel, even though you implicate only the contact dermatitis.”
 

Diagnosis and treatment recommendations

Skin patch allergy testing – in which a person’s skin is exposed to nickel – can quickly determine whether a patient with IBS is actually experiencing inflammatory reactions to dietary nickel and would benefit from a low-nickel or no-nickel diet, research shows.

For these patients, Dr. Pashinsky recommends the following:

• Avoiding high-nickel foods.
• Limiting canned foods.
• Using nonstainless cookware, especially for acidic foods.
• Boiling foods for potential nickel reduction, especially grains and vegetables.
• Running the tap before using water to drink or cook with first thing in the morning.

Dr. Pashisky and her team also recommend the following guidelines for doctors:

• Ask patients if symptoms occur immediately after eating certain high-nickel foods or worsen with a low-FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) diet.
• Determine whether a patient is not responding to typical medical and dietary interventions used to treat IBS.
• Conduct a food/symptom history to identify potential nickel allergy triggers.
• Try a low-nickel dietary intervention to see whether a patient’s symptoms improve in a week or two.
• Refer the patient for additional diagnostic skin-patch testing or treatment.

A multidisciplinary approach

Ms. Finkel said it’s important for doctors, particularly gastroenterologists who treat patients for suspected GI disorders to consider nickel allergy as a cause.

“SNAS is this overlooked condition ... and the research is really in its nascency here,” Ms. Finkel said.

“I would say only give [a low- or no-nickel diet] consideration if the high-nickel foods are a possible trigger,” she said. “It is very specific, looking at their diet history, to have a clear hypothesis based on what their triggers are. It’s not something to try out lightly because it’s a very restrictive diet, so I would never put a patient on a diet that I didn’t think was necessary.”

Ms. Finkel added that treatment of SNAS requires a multidisciplinary approach with a gastroenterologist, an allergist, and a dietitian.

Doctors and dietitians have distinct roles in identifying and treating these patients, Ms. Finkel said.

“If there is a suspicion of IBS symptoms and the patient is not responding to first-line treatments, then it is worth having the input of a dietitian and an allergist,” she said.

A version of this article first appeared on Medscape.com.

Josh struggled for more than a decade with what his doctors had told him was irritable bowel syndrome (IBS). But curiously, the 39-year-old’s flare-ups were caused by some foods that aren’t typical IBS triggers. Peanuts and shellfish caused “stabbing” abdominal pains, and he would feel lightheaded after simply inhaling the scent of them. He also had severe constipation that lasted up to a week and rectal mucous discharges.

So, Josh (not his real name) sought the care of New York gastroenterologist Yevgenia Pashinsky, MD. She conducted a comprehensive nutritional assessment and sent him for allergy testing. The results: Josh had a little-known condition called systemic nickel allergy syndrome (SNAS), which can mimic some of the symptoms of IBS.

Dr. Pashinsky, of the department of medicine at Icahn School of Medicine at Mount Sinai, New York, and a partner with New York Gastroenterology Associates, presented Josh’s case as part of a seminar on SNAS and IBS “mimickers” at the Food and Nutrition Conference and Expo in Orlando last October, sponsored by the Academy of Nutrition and Dietetics.

She and two registered dietitians in her practice, Suzie Finkel, MS, RD, CDN, and Tamara Duker Freuman, MS, RD, CDN, told seminar attendees that SNAS is rarely diagnosed and can be mistaken for IBS. They noted that it probably strikes more people than doctors suspect.

“Systemic nickel allergy is present in at least 10% of the U.S. population (and much higher in some subgroups),” Dr. Pashinsky told this news organization. “But its connection to GI symptoms and functional GI disorders is still being learned about.

“I think of nickel allergy and other allergic disorders when, in addition to GI symptoms, the patient reports skin and mucous membrane involvement along with their abdominal reactions,” she said.

For patients like Josh with SNAS, the diagnosis and treatment of this condition are surprisingly simple and effective.

“Josh had these really [unusual] symptoms and nontraditional IBS food triggers,” Ms. Finkel said in an interview. “So, that’s a situation where, as dietitians we say, ‘Hmm, that’s weird; if you have IBS, then peanuts and shrimp shouldn’t really cause an issue here.’ But this might be something physicians might not be attuned to because it’s not part of their training.”

Ms. Finkel said that Josh was referred to an allergist. Josh tested positive for skin sensitization to nickel, and he was started on a low-nickel diet, which improved his symptoms.

“So, that was this happy ending,” she added.

The upshot?

“Doctors who treat IBS patients [who are not responding to treatment] need to consider the possibility that they have SNAS and send them for allergy testing,” Ms. Finkel said. “If they come back positive, simple dietary changes can address it.”
 

An underrecognized condition

There has been very little research regarding SNAS in patients with IBS, and there are no standard guidelines for diagnosing and treating it.

What’s more, many gastroenterologists aren’t familiar with it. More than a dozen gastroenterologists who were contacted for comment declined to be interviewed because they didn’t know about SNAS – or enough about it to provide useful information for the story.

Ms. Finkel said she’s not surprised that many gastroenterologists don’t know much about how SNAS can mimic IBS, which is why she and her colleagues presented the seminar last October in Orlando. “It’s really an allergy and not a GI disease. It manifests with GI symptoms, but the root is not in the digestive tract; the root is in a true allergy – a clinical allergy – to nickel.”

Complicating the issue is that people who have IBS and those with SNAS typically share some common symptoms.

Like IBS, SNAS can cause GI symptoms – such as cramping, abdominal pain, heartburn, constipation, gaseous distension, and mucus in the stool. It can be triggered by certain fresh, cooked, and canned foods.

But the food triggers that cause SNAS are not usually those that cause IBS symptoms. Rather, SNAS flare-ups are nearly always triggered by foods with high levels of nickel. Examples include apricots, artichokes, asparagus, beans, cauliflower, chickpeas, cocoa/chocolate, figs, lentils, licorice, oats, onions, peas, peanuts, potatoes, spinach, tomatoes, and tea.

According to the American Academy of Allergy, Asthma & Immunology, a distinguishing feature of SNAS is that it can cause allergic contact dermatitis when a person touches something made with nickel. Coins, jewelry, eyeglasses, home fixtures, keys, zippers, dental devices, and even stainless-steel cookware can contain allergy-triggering nickel.

What Ms. Finkel sees the most are skin reactions from touching a surface containing nickel or from ingesting it, she said.

The other immediate symptom is abdominal pain or changes in bowel movements, such as diarrhea, she added.

Christopher Randolph, MD, an allergist based in Connecticut, told this news organization that it’s important for doctors to realize that patients who have a skin reaction to nickel may also have inflammatory GI symptoms.

“We definitely need more controlled studies,” said Dr. Randolph, of the department of allergy and immunology at Yale University, New Haven, Conn. “But the takeaway here is for patients and certainly providers to be mindful that you can have systemic reactions to nickel, even though you implicate only the contact dermatitis.”
 

Diagnosis and treatment recommendations

Skin patch allergy testing – in which a person’s skin is exposed to nickel – can quickly determine whether a patient with IBS is actually experiencing inflammatory reactions to dietary nickel and would benefit from a low-nickel or no-nickel diet, research shows.

For these patients, Dr. Pashinsky recommends the following:

• Avoiding high-nickel foods.
• Limiting canned foods.
• Using nonstainless cookware, especially for acidic foods.
• Boiling foods for potential nickel reduction, especially grains and vegetables.
• Running the tap before using water to drink or cook with first thing in the morning.

Dr. Pashisky and her team also recommend the following guidelines for doctors:

• Ask patients if symptoms occur immediately after eating certain high-nickel foods or worsen with a low-FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) diet.
• Determine whether a patient is not responding to typical medical and dietary interventions used to treat IBS.
• Conduct a food/symptom history to identify potential nickel allergy triggers.
• Try a low-nickel dietary intervention to see whether a patient’s symptoms improve in a week or two.
• Refer the patient for additional diagnostic skin-patch testing or treatment.

A multidisciplinary approach

Ms. Finkel said it’s important for doctors, particularly gastroenterologists who treat patients for suspected GI disorders to consider nickel allergy as a cause.

“SNAS is this overlooked condition ... and the research is really in its nascency here,” Ms. Finkel said.

“I would say only give [a low- or no-nickel diet] consideration if the high-nickel foods are a possible trigger,” she said. “It is very specific, looking at their diet history, to have a clear hypothesis based on what their triggers are. It’s not something to try out lightly because it’s a very restrictive diet, so I would never put a patient on a diet that I didn’t think was necessary.”

Ms. Finkel added that treatment of SNAS requires a multidisciplinary approach with a gastroenterologist, an allergist, and a dietitian.

Doctors and dietitians have distinct roles in identifying and treating these patients, Ms. Finkel said.

“If there is a suspicion of IBS symptoms and the patient is not responding to first-line treatments, then it is worth having the input of a dietitian and an allergist,” she said.

A version of this article first appeared on Medscape.com.

Radiation dermatitis is one of the most common side effects of radiotherapy for women with breast cancer. Results from a phase 3 trial add to previous evidence from smaller trials that show that a silicone-based film can protect skin from this side effect. 

But it is not being used much in clinical practice. Instead, radiation dermatitis is usually treated after the fact, most often with aqueous creams.

The product is Mepitel film, from Swedish medical device company Mölnlycke Health Care.

It should be used for women who are at high risk for developing radiation dermatitis, said Edward Chow, MBBS, PhD, of the department of radiation oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, who was the senior author of the phase 3 study published recently in the Journal of Clinical Oncology.

“Other doctors think that because radiation dermatitis isn’t life-threatening it isn’t as important, but the condition does affect the quality of life for patients,” Dr. Chow said. “If we can lessen the pain and discomfort, why wouldn’t we as physicians?”

Dr. Chow’s open-label, multicenter trial was conducted in 376 women with large breasts (bra cup size C or larger) who were undergoing radiotherapy after lumpectomy or mastectomy. The primary endpoint was grade 2 or 3 radiation dermatitis using the Common Terminology Criteria for Adverse Events. (Grade 2 is described as moderate, whereas grade 3 is severe.) 

The film significantly reduced the incidence of grade 2 or 3 radiation dermatitis, down to  15.5% compared with 45.6% in patients receiving standard care (odds ratio, 0.20, 95% confidence interval, 0.12-0.34, P < .0001). 

There was also a significant reduction in grade 3 radiation dermatitis (2.8% vs. 13.6%; OR, 0.19; P < .0002) and moist desquamation (8% vs. 19.2%; OR, 0.36; P = .002).

“The film was remarkably effective and helped protect patients from potentially debilitating side effects,” commented Corey Speers, MD, PhD, a radiation oncologist with University Hospitals, Cleveland, who saw the study data presented during a plenary session at the annual meeting of the American Society of Clinical Oncology.

He believes that preventing radiation dermatitis before it develops is the best way to care for patients. 

“[Radiation dermatitis] is usually associated with pain and discomfort and can lead to more serious issues like infection or delayed wound healing, and unfortunately, there aren’t effective treatments for it once it’s developed, so preventing it is our most effective strategy,” Dr. Speers said. 

One reason for the film not being used much could be that it takes time apply the film, suggested Patries Herst, PhD, department of radiation therapy, University of Otago, Wellington, New Zealand. She was the lead author of a study published in 2014 that also analyzed the effectiveness of the film in preventing radiation dermatitis.

In their trial, a research radiation therapist applied the film to women when they were starting their radiotherapy. The film is applied to a portion of the breast or chest wall, and Dr. Herst emphasized the importance of applying the film correctly, making sure the film is not stretched during application and not overlapping other pieces of the film, while also making sure that it conforms to the breast shape. The film was replaced when it would curl too much around the sides, approximately every 1 or 2 weeks. 

“Radiation therapy itself is very short. And so you have about 10 minutes for every patient,” she explained.

“But applying the film adds 20-30 minutes and it’s really awkward to apply properly,” Dr. Herst said. “You have to tap it in and then have to maybe cut it so that it fits better. And hospitals say, ‘We don’t have the time’ and that is still the biggest issue that we’re seeing right now.”

In Dr. Chow’s study, the average time spent applying the film on lumpectomy patients was 55 minutes and was slightly shorter at 45 minutes for mastectomy patients. He acknowledged that it does take time that staff at most hospitals and clinics simply don’t have.

Dr. Chow suggested that perhaps a family member or other caregiver could apply the film, and he referenced an educational video from the manufacturer that provides in-depth instructions on the correct way to apply the film for radiotherapy patients. However, this could lead to errors and a waste of product if not the film was not applied properly. 

The cost of Mepitel film may also be a deterrent. Dr. Chow’s study noted that, during the entire course of radiotherapy, the cost for the film was about $80-$100 per patient. However, he believes the benefits outweigh the cost. 

In addition, there have been issues with supplies, and it has been difficult for people to get their hands on the actual product.

Currently, the Mayo Clinic is also conducting a study testing Mepitel Film for radiation dermatitis in breast cancer patients following mastectomy. Mayo Clinic principal investigator Kimberly Corbin, MD, could not go into great detail about the ongoing trial, but she said it has been difficult to get the product. 

“We have been using the film at Mayo for a number of years,” Dr. Corbin said, but we “have found that it is challenging to get supplies.”

“While we have generally been able to have some supply established through our store here, we know that is not typical and it is difficult for patients to access,” she said. In addition, “there are not a ton of centers with experience in application.”

A representative with Mölnlycke Health Care, Allyson Bower-Willner, could not comment on the distribution of Mepitel film in the United States or if the company plans to increase the amount of product shipped. The film is available “to a limited set of customers,” she said.

A version of this article first appeared on Medscape.com.

Radiation dermatitis is one of the most common side effects of radiotherapy for women with breast cancer. Results from a phase 3 trial add to previous evidence from smaller trials that show that a silicone-based film can protect skin from this side effect. 

But it is not being used much in clinical practice. Instead, radiation dermatitis is usually treated after the fact, most often with aqueous creams.

The product is Mepitel film, from Swedish medical device company Mölnlycke Health Care.

It should be used for women who are at high risk for developing radiation dermatitis, said Edward Chow, MBBS, PhD, of the department of radiation oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, who was the senior author of the phase 3 study published recently in the Journal of Clinical Oncology.

“Other doctors think that because radiation dermatitis isn’t life-threatening it isn’t as important, but the condition does affect the quality of life for patients,” Dr. Chow said. “If we can lessen the pain and discomfort, why wouldn’t we as physicians?”

Dr. Chow’s open-label, multicenter trial was conducted in 376 women with large breasts (bra cup size C or larger) who were undergoing radiotherapy after lumpectomy or mastectomy. The primary endpoint was grade 2 or 3 radiation dermatitis using the Common Terminology Criteria for Adverse Events. (Grade 2 is described as moderate, whereas grade 3 is severe.) 

The film significantly reduced the incidence of grade 2 or 3 radiation dermatitis, down to  15.5% compared with 45.6% in patients receiving standard care (odds ratio, 0.20, 95% confidence interval, 0.12-0.34, P < .0001). 

There was also a significant reduction in grade 3 radiation dermatitis (2.8% vs. 13.6%; OR, 0.19; P < .0002) and moist desquamation (8% vs. 19.2%; OR, 0.36; P = .002).

“The film was remarkably effective and helped protect patients from potentially debilitating side effects,” commented Corey Speers, MD, PhD, a radiation oncologist with University Hospitals, Cleveland, who saw the study data presented during a plenary session at the annual meeting of the American Society of Clinical Oncology.

He believes that preventing radiation dermatitis before it develops is the best way to care for patients. 

“[Radiation dermatitis] is usually associated with pain and discomfort and can lead to more serious issues like infection or delayed wound healing, and unfortunately, there aren’t effective treatments for it once it’s developed, so preventing it is our most effective strategy,” Dr. Speers said. 

One reason for the film not being used much could be that it takes time apply the film, suggested Patries Herst, PhD, department of radiation therapy, University of Otago, Wellington, New Zealand. She was the lead author of a study published in 2014 that also analyzed the effectiveness of the film in preventing radiation dermatitis.

In their trial, a research radiation therapist applied the film to women when they were starting their radiotherapy. The film is applied to a portion of the breast or chest wall, and Dr. Herst emphasized the importance of applying the film correctly, making sure the film is not stretched during application and not overlapping other pieces of the film, while also making sure that it conforms to the breast shape. The film was replaced when it would curl too much around the sides, approximately every 1 or 2 weeks. 

“Radiation therapy itself is very short. And so you have about 10 minutes for every patient,” she explained.

“But applying the film adds 20-30 minutes and it’s really awkward to apply properly,” Dr. Herst said. “You have to tap it in and then have to maybe cut it so that it fits better. And hospitals say, ‘We don’t have the time’ and that is still the biggest issue that we’re seeing right now.”

In Dr. Chow’s study, the average time spent applying the film on lumpectomy patients was 55 minutes and was slightly shorter at 45 minutes for mastectomy patients. He acknowledged that it does take time that staff at most hospitals and clinics simply don’t have.

Dr. Chow suggested that perhaps a family member or other caregiver could apply the film, and he referenced an educational video from the manufacturer that provides in-depth instructions on the correct way to apply the film for radiotherapy patients. However, this could lead to errors and a waste of product if not the film was not applied properly. 

The cost of Mepitel film may also be a deterrent. Dr. Chow’s study noted that, during the entire course of radiotherapy, the cost for the film was about $80-$100 per patient. However, he believes the benefits outweigh the cost. 

In addition, there have been issues with supplies, and it has been difficult for people to get their hands on the actual product.

Currently, the Mayo Clinic is also conducting a study testing Mepitel Film for radiation dermatitis in breast cancer patients following mastectomy. Mayo Clinic principal investigator Kimberly Corbin, MD, could not go into great detail about the ongoing trial, but she said it has been difficult to get the product. 

“We have been using the film at Mayo for a number of years,” Dr. Corbin said, but we “have found that it is challenging to get supplies.”

“While we have generally been able to have some supply established through our store here, we know that is not typical and it is difficult for patients to access,” she said. In addition, “there are not a ton of centers with experience in application.”

A representative with Mölnlycke Health Care, Allyson Bower-Willner, could not comment on the distribution of Mepitel film in the United States or if the company plans to increase the amount of product shipped. The film is available “to a limited set of customers,” she said.

A version of this article first appeared on Medscape.com.

Radiation dermatitis is one of the most common side effects of radiotherapy for women with breast cancer. Results from a phase 3 trial add to previous evidence from smaller trials that show that a silicone-based film can protect skin from this side effect. 

But it is not being used much in clinical practice. Instead, radiation dermatitis is usually treated after the fact, most often with aqueous creams.

The product is Mepitel film, from Swedish medical device company Mölnlycke Health Care.

It should be used for women who are at high risk for developing radiation dermatitis, said Edward Chow, MBBS, PhD, of the department of radiation oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, who was the senior author of the phase 3 study published recently in the Journal of Clinical Oncology.

“Other doctors think that because radiation dermatitis isn’t life-threatening it isn’t as important, but the condition does affect the quality of life for patients,” Dr. Chow said. “If we can lessen the pain and discomfort, why wouldn’t we as physicians?”

Dr. Chow’s open-label, multicenter trial was conducted in 376 women with large breasts (bra cup size C or larger) who were undergoing radiotherapy after lumpectomy or mastectomy. The primary endpoint was grade 2 or 3 radiation dermatitis using the Common Terminology Criteria for Adverse Events. (Grade 2 is described as moderate, whereas grade 3 is severe.) 

The film significantly reduced the incidence of grade 2 or 3 radiation dermatitis, down to  15.5% compared with 45.6% in patients receiving standard care (odds ratio, 0.20, 95% confidence interval, 0.12-0.34, P < .0001). 

There was also a significant reduction in grade 3 radiation dermatitis (2.8% vs. 13.6%; OR, 0.19; P < .0002) and moist desquamation (8% vs. 19.2%; OR, 0.36; P = .002).

“The film was remarkably effective and helped protect patients from potentially debilitating side effects,” commented Corey Speers, MD, PhD, a radiation oncologist with University Hospitals, Cleveland, who saw the study data presented during a plenary session at the annual meeting of the American Society of Clinical Oncology.

He believes that preventing radiation dermatitis before it develops is the best way to care for patients. 

“[Radiation dermatitis] is usually associated with pain and discomfort and can lead to more serious issues like infection or delayed wound healing, and unfortunately, there aren’t effective treatments for it once it’s developed, so preventing it is our most effective strategy,” Dr. Speers said. 

One reason for the film not being used much could be that it takes time apply the film, suggested Patries Herst, PhD, department of radiation therapy, University of Otago, Wellington, New Zealand. She was the lead author of a study published in 2014 that also analyzed the effectiveness of the film in preventing radiation dermatitis.

In their trial, a research radiation therapist applied the film to women when they were starting their radiotherapy. The film is applied to a portion of the breast or chest wall, and Dr. Herst emphasized the importance of applying the film correctly, making sure the film is not stretched during application and not overlapping other pieces of the film, while also making sure that it conforms to the breast shape. The film was replaced when it would curl too much around the sides, approximately every 1 or 2 weeks. 

“Radiation therapy itself is very short. And so you have about 10 minutes for every patient,” she explained.

“But applying the film adds 20-30 minutes and it’s really awkward to apply properly,” Dr. Herst said. “You have to tap it in and then have to maybe cut it so that it fits better. And hospitals say, ‘We don’t have the time’ and that is still the biggest issue that we’re seeing right now.”

In Dr. Chow’s study, the average time spent applying the film on lumpectomy patients was 55 minutes and was slightly shorter at 45 minutes for mastectomy patients. He acknowledged that it does take time that staff at most hospitals and clinics simply don’t have.

Dr. Chow suggested that perhaps a family member or other caregiver could apply the film, and he referenced an educational video from the manufacturer that provides in-depth instructions on the correct way to apply the film for radiotherapy patients. However, this could lead to errors and a waste of product if not the film was not applied properly. 

The cost of Mepitel film may also be a deterrent. Dr. Chow’s study noted that, during the entire course of radiotherapy, the cost for the film was about $80-$100 per patient. However, he believes the benefits outweigh the cost. 

In addition, there have been issues with supplies, and it has been difficult for people to get their hands on the actual product.

Currently, the Mayo Clinic is also conducting a study testing Mepitel Film for radiation dermatitis in breast cancer patients following mastectomy. Mayo Clinic principal investigator Kimberly Corbin, MD, could not go into great detail about the ongoing trial, but she said it has been difficult to get the product. 

“We have been using the film at Mayo for a number of years,” Dr. Corbin said, but we “have found that it is challenging to get supplies.”

“While we have generally been able to have some supply established through our store here, we know that is not typical and it is difficult for patients to access,” she said. In addition, “there are not a ton of centers with experience in application.”

A representative with Mölnlycke Health Care, Allyson Bower-Willner, could not comment on the distribution of Mepitel film in the United States or if the company plans to increase the amount of product shipped. The film is available “to a limited set of customers,” she said.

A version of this article first appeared on Medscape.com.

Etiology

Calcareous soils of central and southwest China are home to Primula obconica¹ (also known as German primrose and Libre Magenta).² Primula obconica was introduced to Europe in the 1880s, where it became a popular ornamental and decorative household plant (Figure).³ It also is a frequent resident of greenhouses.

Primula obconica is a member of the family Primulaceae, which comprises semi-evergreen perennials. The genus name Primula is derived from Latin meaning “first”; obconica refers to the conelike shape of the plant’s vivid, cerise-red flowers.

Allergens From P obconica

The allergens primin (2-methoxy-6-pentyl-1,4-benzoquinone) and miconidin (2-methoxy-6-pentyl-1, 4-dihydroxybenzene) have been isolated from P obconica stems, leaves, and flowers. Allergies to P obconica are much more commonly detected in Europe than in the United States because the plant is part of standard allergen screening in dermatology clinics in Europe.⁴ In a British patch test study of 234 patients with hand dermatitis, 34 displayed immediate or delayed sensitization to P obconica allergens.⁵ However, in another study, researchers who surveyed the incidence of P obconica allergic contact dermatitis (CD) in the United Kingdom found a notable decline in the number of primin-positive patch tests from 1995 to 2000, which likely was attributable to a decrease in the number of plant retailers who stocked P obconica and the availability of primin-free varieties from 50% of suppliers.³ Furthermore, a study in the United States of 567 consecutive patch tests that included primin as part of standard screening found only 1 positive reaction, suggesting that routine patch testing for P obconica in the United States would have a low yield unless the patient has a relevant history.⁴

Cutaneous Presentation

Clinical features of P obconica–induced dermatitis include fingertip dermatitis, as well as facial, hand, and forearm dermatitis.⁶ Patients typically present with lichenification and fissuring of the fingertips; fingertip vesicular dermatitis; or linear erythematous streaks, vesicles, and bullae on the forearms, hands, and face. Vesicles and bullae can be hemorrhagic in patients with pompholyxlike lesions.⁷

Some patients have been reported to present with facial angioedema; the clinical diagnosis of CD can be challenging when facial edema is more prominent than eczema.⁶ Furthermore, in a reported case of P obconica CD, the patient’s vesicular hand dermatitis became pustular and spread to the face.⁸

Allergy Testing

Patch testing is performed with synthetic primin to detect allergens of P obconica in patients who are sensitive to them, which can be useful because Primula dermatitis can have variable presentations and cases can be missed if patch testing is not performed.⁹ Diagnostic mimics—herpes simplex, pompholyx, seborrheic dermatitis, and scabies—should be considered before patch testing.⁷

Prevention and Treatment

Preventive Measures—Ideally, once CD occurs in response to P obconica, handling of and other exposure to the plant should be halted; thus, prevention becomes the mainstay of treatment. Alternatively, when exposure is a necessary occupational hazard, nitrile gloves should be worn; allergenicity can be decreased by overwatering or introducing more primin-free varieties.^3,10

Cultivating the plant outdoors during the winter in milder climates can potentially decrease sensitivity because allergen production is lowest during cold months and highest during summer.¹¹ Because P obconica is commonly grown indoors, allergenicity can persist year-round.

Pharmacotherapy—Drawing on experience treating CD caused by other plants, acute and chronic P obconica CD are primarily treated with a topical steroid or, if the face or genitals are affected, with a steroid-sparing agent, such as tacrolimus.¹² A cool compress of water, saline, or Burow solution (aluminum acetate in water) can help decrease acute inflammation, especially in the setting of vesiculation.¹³

Mild CD also can be treated with a barrier cream and lipid-rich moisturizer. Their effectiveness likely is due to increased hydration and aiding impaired skin-barrier repair.¹⁴

Some success in treating chronic CD also has been reported with psoralen plus UVA and UVB light therapy, which function as local immunosuppressants, thus decreasing inflammation.¹⁵

Final Thoughts

Contact dermatitis caused by P obconica is common in Europe but less common in the United States and therefore often is underrecognized. Avoiding contact with the plant should be strongly recommended to allergic persons. Primula obconica allergic CD can be treated with a topical steroid.

Etiology

Calcareous soils of central and southwest China are home to Primula obconica¹ (also known as German primrose and Libre Magenta).² Primula obconica was introduced to Europe in the 1880s, where it became a popular ornamental and decorative household plant (Figure).³ It also is a frequent resident of greenhouses.

Primula obconica is a member of the family Primulaceae, which comprises semi-evergreen perennials. The genus name Primula is derived from Latin meaning “first”; obconica refers to the conelike shape of the plant’s vivid, cerise-red flowers.

Allergens From P obconica

The allergens primin (2-methoxy-6-pentyl-1,4-benzoquinone) and miconidin (2-methoxy-6-pentyl-1, 4-dihydroxybenzene) have been isolated from P obconica stems, leaves, and flowers. Allergies to P obconica are much more commonly detected in Europe than in the United States because the plant is part of standard allergen screening in dermatology clinics in Europe.⁴ In a British patch test study of 234 patients with hand dermatitis, 34 displayed immediate or delayed sensitization to P obconica allergens.⁵ However, in another study, researchers who surveyed the incidence of P obconica allergic contact dermatitis (CD) in the United Kingdom found a notable decline in the number of primin-positive patch tests from 1995 to 2000, which likely was attributable to a decrease in the number of plant retailers who stocked P obconica and the availability of primin-free varieties from 50% of suppliers.³ Furthermore, a study in the United States of 567 consecutive patch tests that included primin as part of standard screening found only 1 positive reaction, suggesting that routine patch testing for P obconica in the United States would have a low yield unless the patient has a relevant history.⁴

Cutaneous Presentation

Clinical features of P obconica–induced dermatitis include fingertip dermatitis, as well as facial, hand, and forearm dermatitis.⁶ Patients typically present with lichenification and fissuring of the fingertips; fingertip vesicular dermatitis; or linear erythematous streaks, vesicles, and bullae on the forearms, hands, and face. Vesicles and bullae can be hemorrhagic in patients with pompholyxlike lesions.⁷

Some patients have been reported to present with facial angioedema; the clinical diagnosis of CD can be challenging when facial edema is more prominent than eczema.⁶ Furthermore, in a reported case of P obconica CD, the patient’s vesicular hand dermatitis became pustular and spread to the face.⁸

Allergy Testing

Patch testing is performed with synthetic primin to detect allergens of P obconica in patients who are sensitive to them, which can be useful because Primula dermatitis can have variable presentations and cases can be missed if patch testing is not performed.⁹ Diagnostic mimics—herpes simplex, pompholyx, seborrheic dermatitis, and scabies—should be considered before patch testing.⁷

Prevention and Treatment

Preventive Measures—Ideally, once CD occurs in response to P obconica, handling of and other exposure to the plant should be halted; thus, prevention becomes the mainstay of treatment. Alternatively, when exposure is a necessary occupational hazard, nitrile gloves should be worn; allergenicity can be decreased by overwatering or introducing more primin-free varieties.^3,10

Cultivating the plant outdoors during the winter in milder climates can potentially decrease sensitivity because allergen production is lowest during cold months and highest during summer.¹¹ Because P obconica is commonly grown indoors, allergenicity can persist year-round.

Pharmacotherapy—Drawing on experience treating CD caused by other plants, acute and chronic P obconica CD are primarily treated with a topical steroid or, if the face or genitals are affected, with a steroid-sparing agent, such as tacrolimus.¹² A cool compress of water, saline, or Burow solution (aluminum acetate in water) can help decrease acute inflammation, especially in the setting of vesiculation.¹³

Mild CD also can be treated with a barrier cream and lipid-rich moisturizer. Their effectiveness likely is due to increased hydration and aiding impaired skin-barrier repair.¹⁴

Some success in treating chronic CD also has been reported with psoralen plus UVA and UVB light therapy, which function as local immunosuppressants, thus decreasing inflammation.¹⁵

Final Thoughts

Contact dermatitis caused by P obconica is common in Europe but less common in the United States and therefore often is underrecognized. Avoiding contact with the plant should be strongly recommended to allergic persons. Primula obconica allergic CD can be treated with a topical steroid.

Etiology

Calcareous soils of central and southwest China are home to Primula obconica¹ (also known as German primrose and Libre Magenta).² Primula obconica was introduced to Europe in the 1880s, where it became a popular ornamental and decorative household plant (Figure).³ It also is a frequent resident of greenhouses.

Primula obconica is a member of the family Primulaceae, which comprises semi-evergreen perennials. The genus name Primula is derived from Latin meaning “first”; obconica refers to the conelike shape of the plant’s vivid, cerise-red flowers.

Allergens From P obconica

The allergens primin (2-methoxy-6-pentyl-1,4-benzoquinone) and miconidin (2-methoxy-6-pentyl-1, 4-dihydroxybenzene) have been isolated from P obconica stems, leaves, and flowers. Allergies to P obconica are much more commonly detected in Europe than in the United States because the plant is part of standard allergen screening in dermatology clinics in Europe.⁴ In a British patch test study of 234 patients with hand dermatitis, 34 displayed immediate or delayed sensitization to P obconica allergens.⁵ However, in another study, researchers who surveyed the incidence of P obconica allergic contact dermatitis (CD) in the United Kingdom found a notable decline in the number of primin-positive patch tests from 1995 to 2000, which likely was attributable to a decrease in the number of plant retailers who stocked P obconica and the availability of primin-free varieties from 50% of suppliers.³ Furthermore, a study in the United States of 567 consecutive patch tests that included primin as part of standard screening found only 1 positive reaction, suggesting that routine patch testing for P obconica in the United States would have a low yield unless the patient has a relevant history.⁴

Cutaneous Presentation

Clinical features of P obconica–induced dermatitis include fingertip dermatitis, as well as facial, hand, and forearm dermatitis.⁶ Patients typically present with lichenification and fissuring of the fingertips; fingertip vesicular dermatitis; or linear erythematous streaks, vesicles, and bullae on the forearms, hands, and face. Vesicles and bullae can be hemorrhagic in patients with pompholyxlike lesions.⁷

Some patients have been reported to present with facial angioedema; the clinical diagnosis of CD can be challenging when facial edema is more prominent than eczema.⁶ Furthermore, in a reported case of P obconica CD, the patient’s vesicular hand dermatitis became pustular and spread to the face.⁸

Allergy Testing

Patch testing is performed with synthetic primin to detect allergens of P obconica in patients who are sensitive to them, which can be useful because Primula dermatitis can have variable presentations and cases can be missed if patch testing is not performed.⁹ Diagnostic mimics—herpes simplex, pompholyx, seborrheic dermatitis, and scabies—should be considered before patch testing.⁷

Prevention and Treatment

Preventive Measures—Ideally, once CD occurs in response to P obconica, handling of and other exposure to the plant should be halted; thus, prevention becomes the mainstay of treatment. Alternatively, when exposure is a necessary occupational hazard, nitrile gloves should be worn; allergenicity can be decreased by overwatering or introducing more primin-free varieties.^3,10

Cultivating the plant outdoors during the winter in milder climates can potentially decrease sensitivity because allergen production is lowest during cold months and highest during summer.¹¹ Because P obconica is commonly grown indoors, allergenicity can persist year-round.

Pharmacotherapy—Drawing on experience treating CD caused by other plants, acute and chronic P obconica CD are primarily treated with a topical steroid or, if the face or genitals are affected, with a steroid-sparing agent, such as tacrolimus.¹² A cool compress of water, saline, or Burow solution (aluminum acetate in water) can help decrease acute inflammation, especially in the setting of vesiculation.¹³

Mild CD also can be treated with a barrier cream and lipid-rich moisturizer. Their effectiveness likely is due to increased hydration and aiding impaired skin-barrier repair.¹⁴

Some success in treating chronic CD also has been reported with psoralen plus UVA and UVB light therapy, which function as local immunosuppressants, thus decreasing inflammation.¹⁵

Final Thoughts

Contact dermatitis caused by P obconica is common in Europe but less common in the United States and therefore often is underrecognized. Avoiding contact with the plant should be strongly recommended to allergic persons. Primula obconica allergic CD can be treated with a topical steroid.