Irritation from surfactants contained in detergents is a frequent adverse reaction to cosmetics. Sensitization to surfactants is also possible. In the literature, comparative studies about irritant and sensitizing potential of different surfactants are heterogeneous and inconclusive about the best molecules to use.
We compared the irritant and sensitizing potential of some surfactants that are usual components in marketed synthetic detergents (syndets) to obtain practical information regarding commonly used detergents.
We patch-tested eight surfactants of the different types (anionic, cationic, amphoteric, and non-ionic) in 105 patients. Assessment of allergic reactions of tested surfactants was carried out in accordance with the recommendations of the International Contact Dermatitis Research Group; assessment of irritant power followed the amended Draize classification.
None of the eight surfactants in our series gave positive allergic reactions. Only cocamidopropyl betaine from the Italian standard (Societa Italiana di Dermatologia Allergologica, Professionale e Ambientale [SIDAPA]) series gave five positive reactions among 105 patients. None of the eight studied surfactants induced skin irritation. The most tolerated are two new mild anionics (sodium cocoyl glutamate and sodium lauroyl oat amino acids) and an amphoteric agent (disodium cocoamphodiacetate).
From this study, we deduce that cosmetic companies' efforts to search for and market new products with very mild surfactants have been generally successful.