Allergic contact dermatitis to 3-O-ethyl-L-ascorbic acid: An underrated allergen in cosmetics?

3-O-Ethyl-L-ascorbic acid [(2R)-2-[(1S)-1,2-dihydroxyethyl]-3-ethoxy-4-hydroxy-2H-furan-5-one] (CAS no. 86404–04-8), or ethyl ascorbicacid, is an ether derivative of ascorbic acid (vitamin C). 1 The latter ispresent in several foods and dietary supplements. Conversely to thequickly cutaneous degrading of ascorbic acid, the ether group of ethylascorbic acid ensures a greater molecular stability, enhancing its trans-port through skin. Moreover, due to its lipophilic and hydrophilicproperties, ethyl ascorbic acid is used in several cosmetics formula-tions for its whitening, antioxidant, anti-inflammatory, and elasticizingproperties. Despite its frequent use in cosmetics, ethyl ascorbic acidis only rarely reported as a cause of allergic contact dermatitis(ACD)