Allergic contact dermatitis due to cosmetics containing vitamin K1 oxide.

Vitamin K denotes a group of molecules that are needed for the synthesis of certain proteins, mostly required for blood coagulation. Five isoforms of vitamin K exists: vitamin K1, K2, K3, K4, and K5. Vitamin K1 (phytonadione, CAS number 84-800/81818-54-4) has been widely used in cosmetics as it is claimed to reduce the purpura and hyperpigmentation associated with surgical and laser therapies (1). Recently, as a result of its sensitizing potential (2), this substance has been forbidden in the EU as an ingredient of cosmetics. However, there is no restriction on the use of the oxidized-isoform of vitamin K1, vitamin K1 oxide (phytonadione epoxide, CAS number 25486-55-9) and it remains in use in cosmetics in Europe. In this study, we report three cases of allergic contact dermaitis from vitamin K1 oxide.