Allergic contact dermatitis from shellac in mascara.

We report 6 cases of allergic contact dermatitis of the eyelids due to mascara. Allergy occurred in women aged 17-34 years, between September 1999 and June 2001. The main ingredient responsible for allergy was shellac, which gave positive patch test reactions in 5/5 patients. This resinous substance is mainly used in cosmetics, food and industry. The exact nature of the hapten remains unknown, and its presence and level in shellac can vary with the source and the treatments applied to it. One patient was also sensitized to quaternium-22, a quaternary ammonium compound in the cosmetic. These reports underline the rôle of networks, such as REVIDAL-GERDA, in monitoring the emergence of contact allergens and disseminating such information among the medical community.