Beauty Chat: Dermatologist Noëlle Sherber on Cosmetic Allergies

Allergens are usually preservatives, fragrances, colors, or formaldehyde-releasing agents like imidazolidinyl urea or quaternium 15. Methylisothiazolinone (MI) is a preservative the American Contact Dermatitis Society is concerned about, since it's recently been allowed in higher concentrations in cosmetics than before, which may account for the increase in allergies. MI is often in baby wipes and makeup-removing or cleansing wipes, and I've had patients develop facial eczema that I can trace back to them using cleansing wipes rather than a traditional rinse-off cleanser. As mineral makeups have become more popular, I've seen many cases of eczematous rashes due to its shimmery mica, and acne eruptions due to bismuth, which is included in some brands' formulations.

Because eyelid skin is so thin, allergies to products applied in this area are common—eye creams, eye shadows, and mascaras, especially. I've seen a lot of allergies to long-wear products for eyelids and eyelashes, which may due to the many chemicals they combine to make it last for 12 hours or more.

You'll know—the most common type of cosmetic allergy is called "irritant contact dermatitis" and means red, itchy, rough skin where you've applied the product, and sometimes comes with a stinging or burning feeling. Another type of reaction I see is "acne cosmetica," red inflammatory acne bumps without the blackheads you'd see with the usual form of acne. The most severe allergic reaction, called "allergic contact dermatitis," can cause blistering and poison ivy-like eruptions, or even facial swelling, and means you should see a doctor right away.

First, see a dermatologist to settle your skin down with anti-inflammatory treatments. Acids and retinoids, like glycolic acid and Retin-A, thin out the skin's barrier, making you more vulnerable to cosmetic allergies, so stop using them immediately. Start a bland skin regimen of gentle products until you determine the source of the allergy.

Allergies are tricky because a new product you used isn't always to blame. The reality is that you could use an eyeshadow 1,000 times and on the 1,001st time, you cross over from becoming gradually sensitized without symptoms to having a full-blown allergy [attack]. As long as you don't have facial swelling, you can do a basic allergy test at home. If you think that you're allergic to a shimmery blush, for example, test it on your inner forearm in the same way you would on your face, applying a thin layer in the morning and removing it with cleanser in the evening as you would your usual makeup. Do this every day for a week and watch for a rash to develop. If so, you have your answer; if not, move on to another product and repeat, one by one. Or a dermatologist can do a patch test, where little dots of different topical ingredients are applied to your back in a grid, and she examines the skin to see which chemicals produced a reaction.

There's never a guarantee. Something may be hypo-allergenic but still cause an allergy for you, just as most people can eat strawberries, but some people may be allergic to them. Products for sensitive skin generally contain fewer common allergens, but they still can provoke an allergy in someone who's susceptible. For my patients with exceedingly sensitive skin, I recommend that they use only baby skin care products, a gentle balm cleanser like Eve Lom Cleanser, and moisturize with plain oils, like grapeseed oil. In general, the longer a product stays on your skin, the greater potential for allergy. Once you figure out your trigger ingredient, become a master at reading cosmetic ingredient labels so you can protect yourself.