Most individuals can use cosmetic products without difficulty. However, despite intensive efforts to formulate hypoallergenic products, there is still a small percentage of people suffering from skin irritations and allergic contact dermatitis when they use cosmetics. The overall frequency of dermatitis produced by cosmetics is difficult to determine. If the consumer experiences a reaction that is mild and transient, he/she will not usually seek medical attention, but simply stop using the suspected product. In addition to eczema, sometimes consumers experience only a slight burning, stinging, or itching without visible skin lesions. Such minor allergies are usually not reported.

There are 3 categories of cosmetic ingredients that induce allergies more often than others: Fragrances, preservatives, and hair colorants & agents for permanent waves Fragrances are the most frequent allergens, but specific allergen avoidance is complicated by the fact that manufacturers are not required to disclose the exact fragrance ingredients in products. Also, when a product lists essential oils, patients may not recognize this as fragrance.

Another important cause of contact dermatitis caused by cosmetics is the variety of preservatives added to the cosmetic products to prevent microbial contamination. For example, formaldehyde releasers are frequent allergens. Other important causes of contact allergy include the active agents in hair- and nail-care products such as those for permanent hair waves, permanent hair coloring, artificial nails, and nail polishes.

Frequency of Skin Irritations (North American Contact Dermatitis Group):
Balsam of Peru: 12.3 %
Fragrances including essential oils: 11.7 %
Thimerosal: 10.8 %
Formaldehyde: 9.3 %
Quaternium-15: 9.0 %
p-Phenylenediamine: 4.9 %
p-Aminobenzoic acid: 3.2 %
2-Bromo-2-nitropropane-1,3-diol: 3.1 %
Imidazolidinyl urea: 2.5 %
Lanolin alcohol: 2.4 %
Glyceryl thioglycolate: 2.0 %
Kathon CG: 1.4 %
Toluene sulfonamide formaldehyde resin: 1.3 %
Methyl methacrylate: 1.3 %
Parabens: 1.0 %
Oxybenzone: 0.6 %