Long-term risks of psoralen and UV-A therapy for psoriasis.

It has been more than eight years since photochemotherapy with methoxsalen and UV-A (psoralen and UV-A [PUVA]) was introduced for the treatment of psoriasis. This treatment remained under investigation until May 1982 because of concerns about possible chronic toxic effects. With recent Food and Drug Administration approval of PUVA therapy for severe psoriasis, strict drug labeling for administration and patient use and continued monitoring of side effects have become essential. The full effects of PUVA in regard to carcinogenicity, prematurely induced aging of the skin, pigmentary changes, immunologic alterations, and ocular side effects are still unknown. A review of the risks of PUVA therapy is presented, with the aim of maintaining a proper perspective for its limited use in treating selected patients.