Treatment of chronic urticaria with PUVA or UVA plus placebo: a double-blind study.

Chronic urticaria is a disease for which the available range of treatment modalities is limited. Ultraviolet radiation has recently been shown to affect histamine release from mast cells. We therefore studied the effects of PUVA and UVA on chronic urticaria. Nineteen patients took part in the study, which was designed as a randomized double-blind study. Eleven patients received PUVA, and 8 received UVA plus a placebo. In the PUVA group, 7 patients showed improvement, 3 noticed no change, and 1 became worse. In the group that received UVA plus placebo, 5 patients experienced an improvement, whereas the other 3 showed no change. The differences between the groups were not statistically significant. However, the probability of achieving this degree of improvement in both groups just by chance is less than 1%. Consequently, the improvement noted could have been due to either UVA alone or a placebo effect. It is concluded that PUVA is not better than UVA in the treatment of chronic urticaria.