Psoralen is a light-sensitive drug that absorbs ultraviolet (long wave - UVA) light and acts like ultraviolet radiation. Psoralens are used together with ultraviolet light (PUVA therapy) to treat skin conditions such as vitiligo, eczema, psoriasis and skin problems related to certain lymphomas.
Psoralens are either taken orally or applied topically where the patient soaks in a bath containing the psoralen, then UVA light is applied to treat the skin condition.