Allergic contact dermatitis from stearamidoethyl diethylamine phosphate: a cosmetic emulsifier

Contact dermatitis to the emulsifier stearamidoethyl diethylamine phosphate was demonstrated in 4 patients. In 3 patients, the emulsifier was present in a commonly used over-the-counter dry skin lotion and in the 4th in a deodorant. In 2 cases, the patients overtly suspected that the product was the cause of the dermatitis. Patch tests to the products were positive. The emulsifier was identified as the contact allergen after testing with coded deletion and/or individual ingredient samples provided by the manufacturer. No apparent cross reactions were found from testing with the standard screening tray of the North American Contact Dermatitis Group or in one case to 2 structurally similar emulsifiers. No other positive reactions to the emulsifier were found after testing it routinely in one patch test clinic for 1 year. Repeated insult (prophetic) patch testing with the final formulation of the dry skin lotion (as performed by the manufacturer) was negative for sensitization and irritation.