Solar urticaria treatment by inducing tolerance to artificial radiation and natural light.

Solar urticaria was treated by means of repeated exposures of the skin to fluorescent lamps or natural sunlight. Repeated exposures over a period of hours induce a state of tolerance in the skin so that urticaria fails to develop. The state of tolerance can be maintained with regular daily exposures, and treatment can lead to complete symptomatic relief. Determination of the action spectrum for urticaria is advisable in order to choose the correct fluorescent lamp for treatment.