Treatment of psoriasis with orally administered 8-methoxypsoralen and long-wavelength ultraviolet radiation.

Between May 1976 and September 1977, 51 patients with severe psoriasis were treated with orally administered 8-methoxypsoralen followed by exposure to high-intensity long-wavelength ultraviolet radiation. Clearing of psoriasis occurred in 40 patients (78%) and marked improvement in 5 (10%). Of the remaining patients three (6%), who had generalized erythroderma, failed to respond to this therapy. The mean number of treatments required for clearing was 37.5. No serious side effects were noted clinically, by ophthalmologic examination or by laboratory testing. This therapy has some advantages over conventional types of treatment now used for severe psoriasis, but also has limitations. It appears to be an effective method of treatment for ambulatory patients. Further long-term follow-up studies are required to evaluate its side effects.