Evaluation of oral minoxidil in the treatment of alopecia areata.

A dose-response effect has previously been demonstrated in topical minoxidil treatment of alopecia areata. Limitations in minoxidil solubility and percutaneous absorption have impaired the development of more effective topical therapy. Oral minoxidil (5 mg every 12 hours), a dose demonstrated to be relatively well tolerated if a 2-g sodium diet is strictly followed, was given to 65 patients with severe, treatment-resistant alopecia areata in an attempt to bypass the limitations of topical treatment and increase efficacy. Although hair regrowth progressed more rapidly and was more extensive with oral than topical 5% minoxidil, cosmetic response was seen only in 18% of the patients. Neither serum nor tissue levels of minoxidil correlated with response. These findings suggest that improved preparations of topical minoxidil, when used as a single therapeutic agent, are unlikely to be cosmetically effective in the majority of patients with severe alopecia areata.