More than 50 percent of all cases of true allergies to cosmetics have been linked to the use of skin and hair care products and grooming agents that are intended to be left on the skin. The face and the region immediately around the eyes are the sites most often involved. Moisturizers, makeup, and sunscreens comprise the bulk of these "leave-on" products, and the fragrances and preservatives in them are most often the allergenic substances responsible for the adverse reactions. In general, as in the case of direct irritation, application of any product to previously inflamed skin increases the likelihood of adverse allergic reactions.
Of the most frequently used cosmetic ingredients, fragrances are the most common cause of allergic cosmetic allergy. In fact, scented products that are applied to skin which has become irritated or inflamed for one reason or another is believed to be responsible for most instances of cosmetic allergies. Products that contain fragrance moisturizers, makeup, deodorants and antiperspirants, sunscreens, and, of course, perfume have all been found capable of provoking these reactions.
Unfortunately, it is often difficult for fragrance allergy sufferers and their doctors to identify the scents that are responsible for the contact allergies. This is because fragrance formulations are often complex mixtures of chemicals, and many of these combinations are jealously guarded as "trade secrets" by the cosmetic and pharmaceutical houses that produce them. Some of the better known fragrance allergens include cinnamic alcohol, musk ambrette, hydroxycitronellal, isoeugenol, eugenol, geraniol, cinnamic aldehyde, and coumarin.
Note: Don't be fooled by the term unscented when searching for products that do not contain fragrances. Unscented and fragrance-free do not necessarily mean the same thing. While fragrance-free indicates that scents have been eliminated from the formulation altogether, unscented usually means that one or more scents have actually been added to a product with an otherwise medicinal or industrial aroma to render the final formulation less offensive to smell. Thus, if you are found to be allergic to fragrances, you should avoid scented products altogether and stick with fragrance-free items only.
Preservatives the special ingredients used to prevent bacterial contamination and increase product shelf life are the second most common cause of cosmetic contact allergy. Quartemium 15, a formaldehyde-releasing agent found in many moisturizers and hair care items, is a particularly common culprit in this category, and more than half of the individuals with quartemium 15 allergy are also allergic to formaldelhyde, another commonly used preservative. (For unexplained reasons, African-Americans have been found to be especially susceptible to this form of allergy.) Imidazolidinyl urea is the next most common cosmetic preservative allergen, followed by the parabens, 2-bromo-2-nitropropane-l, 3-diol, sorbic acid, diazolidinyl urea, MCI/MI (also listed on ingredient labels by its trade name, Kathon CG), glutaraldehyde, MGP (also known as Euxyl K-400), ben-zalkonium chloride, thimerosal, p-chloro-m-cresol, chloroxylenol, benzyl alcohol, sorbic acid, cetyl and stearyl alcohol, chloroacetamide, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), ethylenediaminetetraacetic acid (EDTA), and captan.
Lanolin (wool wax) and lanolin derivatives found in many commercial moisturizers and emollients make up another fairly large category of cosmetic allergens. In one study approximately 5 percent of all allergic reactions to cosmetics were related to these ingredients.
And lastly, the cosmetic allergens most often responsible for nail allergies include toluenesulfonamide/formaldehyde resin within nail enamels, free formaldelhyde in nail hardeners, methacrylate resins in sculptured and bonded nails, and the cyanoacrylate glues in nail repair kits.
