The dark side of the light: Phototherapy adverse effects.

Phototherapy is a valuable therapeutic tool in Dermatology, but there may be drawbacks. Acute and long-term adverse effects, of variable severity, include skin erythema, xerosis, pruritus, blistering, altered pigmentation, photoaging, and photocarcinogenesis. Despite concerns over the carcinogenic potential of ultraviolet radiation, most studies have not found an increased risk of non-melanoma or melanoma skin cancer in patients treated with ultraviolet B (broadband and narrowband) and ultraviolet A1 phototherapy. These are therefore considered reasonably safe treatment modalities concerning the development of skin neoplasms, although caution and further investigation are warranted. Photoprotective measures, such as avoidance of concurrent sunlight exposure and covering skin areas not afflicted with disease, or more modern strategies, including phytochemical antioxidants and exogenous DNA repair enzymes, can minimize the hazards of phototherapy. Patients submitted to phototherapeutic regimens should undergo complete, careful dermatologic examination regularly and lifelong.