Ronald R. Brancaccio, M.D., a clinical associate professor of dermatology at New York University Medical Center. Dr. Brancaccio also has a dermatology practice in New York City.
Rashes due to nail cosmetics are common. In fact, a recent study in Italy of 888 women with an allergy to cosmetics revealed that the formaldehyde resin in nail polish was the second most common cause of allergy in this group, placing right behind hair dye.
Sculptured nails also cause a lair share of allergic reactions. Nail clients can develop allergies to nail adhesives (including the fast-drying type) and methacrylate-based acrylics. In the late 1970s, the U.S. Food and Drug Administration banned methyl methacrylate because of reported allergic reactions to the chemical. Ethyl methacrylate has a low incidence of allergic reactions. The newer UV light-cured acrylate gels also have been reported to cause allergic reactions. In addition, some nail polishes and treatments contain formaldehyde, a known sensitizer that can cause allergic reactions.
The kinds of allergic reactions that you may see appear as eczema, an itchy, scaling red rash that may have small groups of water Misters. This reaction is called an allergic contact dermatitis because it is caused by a chemical coming in direct contact with the skin and causing an allergic reaction.
Interestingly, with nail cosmetics the rash does not always appear on the fingertips, but sometimes only on the face, eyelids, and neck. These are areas the person touches with her lingers before the nail cosmetic is completely dry. This is called ectopic contact dermatitis because, like an ectopic pregnancy, it occurs where one would not expect it to.
Sensitization to a chemical develops over a period of lime, usually a few months to several years. Allergic contact dermatitis does not develop immediately after a cosmetic is applied to the skin; usually one to seven days pass before a rash appears. This is the same kind of reaction that occurs with poison ivy. One goes walking in the woods and several days later an itchy rash appears. One of my patients who is allergic to nail polish got a rash just around her lips that did not develop until four days alter she applied nail polish. This woman did not have a rash on her fingertips. It was only after extensive testing that we determined the cause of her allergy. The rash cleared when she began using a nail polish that does not contain toluene-sulfonamide resin.
While chemicals used in nail cosmetics can cause allergic contact dermatitis, many of these same chemicals can produce an irritant contact dermatitis when a concentrated amount of the chemical comes into contact with skin. Irritant contact dermatitis has symptoms similar to those of allergic contact dermatitis, but irritant contact dermatitis is not an allergic reaction. Rather, irritant contact dermatitis comes from damage to skin cells caused by overexposure to a harsh chemical. For example, nail primer is a chemical that is irritating to the skin.
How can you diagnose whether a reaction is an irritant contact dermatitis or an allergic contact dermatitis? Patch testing is the only accurate and reliable method of differentiating between allergic and irritant types of dermatitis. Physicians patch test patients by applying a standardized concentration of the suspected chemical onto a disk that is then taped to the patient’s back or arm and left in place for 48 hours. After the disk is removed, a reaction in the form of redness or itchy bumps is evaluated.
A patch test should be performed only by a physician, preferably a dermatologist, who is trained in this technique. Although some nail cosmetics can be tested “as is” (without a .standardized concentration), you risk burning the skin and causing an irritant contact dermatitis reaction. One nail technician I recently spoke to had patch tested herself for an allergy to nail primer. Despite removing the patch after 45 minutes and washing the skin, the next day she had a large blister on the area. This patch test reaction was not an allergy, but actually a chemical burn.
Another reason why only a specialist should perform patch tests is that the reactions are difficult to interpret, may take up to a week to develop, and are unpredictable. It is very difficult even for a dermatologist to “guess” which product is the one causing a reaction. We’re often surprised to see what reactions develop when we patch test a patient. The procedure, although it seems easy to perform, requires years of experience to interpret the results properly. These difficulties are further compounded by the fact that contact dermatitis can also be caused by a wide variety of chemicals. For example, when a client who wears nail cosmetics develops a rash around her nails, we must also consider the ingredients in the perfumes, moisturizers, and hand creams that she uses.
Finally, patch testing someone for an allergy to a chemical can actually cause them to become allergic to that chemical.
So what can a nail technician do to help a client who develops a rash? Advising the client to see her dermatologist is the best first step. If your client is reluctant lo see her doctor, you can stop using on her for a week or two those products that you suspect are causing the rash. Of course, the rash should be treated by a doctor anyway or it may persist long after she stops using the product that caused it.
Another method nail technicians can use to determine whether a client is allergic to a chemical is called a use test or provocative test, in which the product is applied to one fingernail and observed for a week. This is a good, but not 100% perfect, way of seeing if a product is safe for a client.
I recommend against nail technicians performing patch tests on their clients. Such diagnostic tests should he performed only by a dermatologist. Nor do I think every client should he subjected to a use test on one nail before she has a product applied to all her nails. If a client has no history of skin reactions to nail cosmetics and if no rash is present, there is no need lo test her for allergies. We are not born with this type of allergy. An allergic contact dermatitis develops with repeated exposure to a chemical over a period of time. Additionally, new nail cosmetics enter the market each year, and companies may even change some of their ingredients without changing the name of the product. There’s no way to foretell whether a product your client can wear today is one she’ll be allergic to next month.
The good news is that once an allergy is recognized and diagnosed properly, substitute products can be found so that the client can continue to enjoy the beauty of these cosmetics.