Treatment of polymorphous light eruption with nicotinamide: a pilot study.

In a pilot study, 42 patients suffering from polymorphous light eruption (PLE) were treated with oral nicotinamide, 3 g daily, for 2 weeks. Twenty-five patients remained free from lesions despite extensive sun exposure. We suggest that an abnormality in tryptophan metabolism is important in the aetiology of PLE, and that nicotinamide administration partially corrects this.