Low-dose oral minoxidil (5 mg once daily) was found to have similar effectiveness to topical minoxidil (5% twice per day) for the treatment of male androgenetic alopecia (AGA). 

The authors conducted the double-blind, placebo-controlled randomized clinical trial in Brazil aiming to evaluate the efficacy, safety, and tolerability of low-dose oral minoxidil compared to topical minoxidil in treating male AGA. The study included 90 men aged 18 to 55 years with AGA classified as 3V, 4V, or 5V on the Norwood-Hamilton scale. Participants were randomized into one group receiving daily oral minoxidil (5 mg) and topical placebo, and the other group receiving topical minoxidil (5%) twice daily and oral placebo. The study period was 24 weeks. Primary outcome measures included change in terminal hair density on the frontal and vertex regions of the scalp, with secondary outcomes including changes in total hair density and photographic evaluation.

Of the 90 enrolled participants, 68 completed the study, with both groups showing homogeneity in demographic data and AGA severity. Oral minoxidil did not demonstrate superiority over topical minoxidil for efficacy. The mean change in hair density from baseline to week 24 was not significantly different between the two groups, although oral minoxidil was found to be superior to topical minoxidil on the vertex area (according to photographic analysis). The most common adverse effects observed in the oral minoxidil group were hypertrichosis and headache.

"Low-dose oral minoxidil (5 mg per day) had similar efficacy to topical minoxidil, 5%, for men with androgenetic alopecia and can be an option for patients who prefer oral therapy or are intolerant to topical treatment," the researchers wrote.

The study was published in JAMA Dermatology.