Ultraviolet A phototherapy in the prophylaxis of solar urticaria.

Five patients with solar urticaria were treated with ultraviolet A (UVA) radiation. Three experienced marked increases in sunlight tolerance, but two patients failed to improve. Subjective clinical improvement was documented objectively by marked increases in the minimal urtication doses obtained by provocative light testing. These results indicate that some patients with solar urticaria may respond to treatment with UVA radiation alone.