Comparison of crude coal tar and topical methoxsalen in treatment of psoriasis.

Fluorescent sunlamp bulbs have been an effective light source for treatment of psoriasis when they are used in combination with crude coal tar. In addition to their ultraviolet B (UVB) emission, the spectral output of these bulbs contains a substantial amount of ultraviolet A (UVA). Prior testing with this light source and topically applied methoxsalen achieved excellent results in psoriasis. This study compared topically applied methoxsalen to crude coal tar in 16 patients who had plaque-type psoriasis, using the same fluorescent sunlamp source of irradiation. Fourteen of 16 patients had complete clearing of plaques when they were treated with methoxsalen, compared with six patients who had complete clearing with the tar treatment. These results indicate that the use of methoxsalen and ultraviolet light may be more effective than tar, when used as they were in this study. The advantages of a clean, white, nonstaining topical agent also makes outpatient therapy more cosmetically acceptable.