Allergic contact dermatitis caused by 3-o-ethyl-L-ascorbic acid (vitamin C ethyl).

Skin-lightening agents such as kojic acid, arbutin, ellagic acid, lucinol and 5,5′-dipropylbiphenyl-2,2′-diol are used in ‘anti-ageing’ cosmetics. Cases of allergic contact dermatitis caused by these skin-lightening agents have been reported (1, 2). Vitamin C and its derivatives have also been used in cosmetics as skin-lightening agents for a long time. Vitamin C in topical agents is poorly absorbed through the skin, and is easily oxidized after percutaneous absorption. Recently, ascorbic acid derivatives have been developed with enhanced properties. The ascorbic acid derivative 3-o-ethyl-l-ascorbic acid (CAS no. 86404-048, molecular weight 204.18; Fig. 1), also known as vitamin C ethyl, is chemically stable and is more easily absorbed through the skin than the other vitamin C derivatives. Moreover, 3-o-ethyl-l-ascorbic acid has skinlightening properties. Here, we report a case of allergic contact dermatitis caused by a skin-lightening lotion containing 3-o-ethyl-l-ascorbic acid.