Comparative treatment of psoriasis with UV-light, trioxsalen plus UV-light, and coal tar plus UV-light.

Areas within psoriasis plaques have been treated with UV-light alone, trioxsalen plus UV-light, and coal tar (liquid carbonis detergens) plus UV-light, using the 313, 365 and 405 nm wavelength bands in various doses. With the 313 nm band, the same degree of healing was obtained with all three types of treatment. With the 365 nm band, no healing was achieved with UV-light alone, but healing did occur with UV-light when the skin was sensitized with trioxsalen. Coal tar itself has a certain healing effect on psoriasis but the effect is so markedly enhanced by light of the 365 nm band that the healing is comparable to that obtained with the 313 nm band. No healing was seen with light of the 405 nm band. The patients who were healed with the 313 nm band alone, also healed with trioxsalen or coal tar plus UV-light of the 365 nm band. With each method there is an individual optimal light dose of 1--2 MED that gives healing.