Ultraviolet phototherapy in psoriasis with hydrophilic ointment alone or with crude coal tar.

Plaques of 12 psoriatic patients treated with crude coal tar and ultraviolet irradiation were compared with symmetric areas treated with the same ultraviolet light (UVL) source and a hydrophilic ointment vehicle. Of the 12 patients, 10 received 75-100% clearing at both sites regardless whether the tar or the vehicle was applied. Treatment three times weekly was as effective as five times weekly. It was uncertain if the addition of UV-A irradiation to the UVL system in a small group using tar had a more beneficial effect.