Sunscreening agent can be culprit in contact dermatitis

David Cohen, MD, MPH

David Cohen, MD, MPH

The first few months of each year is awards season, and although it doesn’t get the attention of the Grammys or Oscars, the Allergen of the Year does make an impact — especially among dermatologists. This year the top allergen, according to the American Contact Dermatitis Society, is the family of benzophenones.

Benzophenones are organic compounds that help block ultraviolet B light to protect scents and colors, and so are commonly used in sunscreens, perfumes, and soaps. The choice as allergen of the year is surprising because benzophenones have a low prevalence of reactivity, said David Cohen, MD, MPH, director of Friday’s Hot Topics symposium, who discussed contact dermatitis during the symposium.

“There are a lot of benzophenones, at least a dozen that are used industrially and in products people put on their skin. By far, benzophenone-3, also known as oxybenzone, is the most common and is used in a lot of sunscreening agents. Benzophenone-4 is called sulisobenzone. They are the two benzophenones people come across the most in sunscreen chemicals and cosmetic agents,” said Dr. Cohen, Charles C. and Dorothea E. Harris professor of dermatology at New York University Langone Medical Center.

Contact dermatitis in benzophenones is not common, with a prevalence of reactivity of only 0.9 percent in those who are patch-tested for it, he said.

“It is rare, but the point is that in cases where people suspect allergy to this sunscreening chemical, oxybenzone is going to be the most likely one,” Dr. Cohen said. “I am not advocating the avoidance of oxybenzone or benzophenone-4 prophylactically. I don’t see any reason to do it for allergy reasons because it has been on the market for so long and the prevalence of reactions are still very low. But in those cases where you worry about it or another disorder — photocontact dermatitis, where people get allergic to the chemical plus the light — then I think you ought to consider oxybenzone as a potential agent.”

A second agent dermatologists should be aware of is the 2013 allergen of the year, methylisothiazolinone, which for many years was blended with methylchloroisothiazolinone in the preservative Kathon.

“This was a very important allergen to call out to the general population of dermatologists and our patients because this nonformaldehyde-releasing preservative was really starting to appear frequently in cosmetic and personal-care products like shampoos, soaps, and wipes,” Dr. Cohen said.

When mixed with methylchloroisothiazolinone, methylisothiazolinone was not linked to strong reactions. However, it is now used by itself in a number of wipes and carry-around cleansers, he said.

“Methylisothiazolinone has broken off to a solo agent in higher concentration, and it seems to be causing a higher prevalence of contact dermatitis than we originally recognized when we were testing the mix,” Dr. Cohen said. “Exposure is common, and we need to recognize the changing sources of common contact allergens.”

Even though some allergens may not be common, he said, it is important to make people aware of them.

“The lesson is that people frequently implicate sunscreen chemicals as the cause of contact dermatitis, when in fact they are not that common,” Dr. Cohen said. “For sunscreens, the most important things to look at are the sunscreen chemicals and fragrances, and sometimes preservatives and vitamin E in the product. That is the take-home message. The sunscreens are commonly implicated in problems, and I think people are targeting the wrong part of it.”

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