The research shows that 0.5 milligrams a day of oral dutasteride had the highest probability of reducing male hair loss.

The top-ranking hair loss treatment for men is dutasteride (Avodart) capsules, at a dose of 0.5 milligrams a day, according to a new meta-analysis of 23 studies published online Feb. 2 in JAMA Dermatology. 

When researchers compared various dosages of the three oral and topical medications -- minoxidil, dutasteride and finasteride, they found that dutasteride produced the biggest increase in total hair count after six months of use. Next up was finasteride (Propecia) pills, taken at a 5-mg dose each day, followed by the same dose of oral minoxidil (Rogaine), the study showed.

A lower dose of finasteride (1 mg a day) ranked fourth, followed by two topical formulations of minoxidil, with the higher dose (5%) performing better than the lower (2%), and low-dose oral minoxidil, taken as 0.25 mg per day, ranking at the bottom.

“The findings of this meta-analysis contribute to the comparative effectiveness literature for androgenetic alopecia therapies with regard to the compared interventions,” the study authors conclude.