Double-blind treatment of seborrheic dermatitis with 2% ketoconazole cream.

Thirty-seven patients with seborrheic dermatitis were treated topically with a 2% ketoconazole cream or its vehicle control in a double-blind study. The subjects were studied for numbers of Malassezia ovalis (Pityrosporum ovale) cells in their scalp scale; changes in numbers of yeast cells and morphology of M. ovalis were tabulated along with clinical assessment of improvement. The 2% ketoconazole cream, but not the placebo cream, reduced the numbers of viable yeast cells on the scalp. The clinical effect of 2% ketoconazole cream was good (75%-95% improvement) or better in eighteen of twenty subjects; the placebo cream produced good results in only three of seventeen subjects treated. Results of this study are consistent with the view that M. ovalis plays a central role in the pathogenesis of seborrheic dermatitis.