Oral finasteride is an FDA‐approved treatment for androgenetic alopecia (AGA). Topical finasteride, while not FDA‐approved, lacks the systemic adverse effects associated with oral finasteride. The efficacy of topical finasteride has been evaluated.

To review whether topical finasteride is a safe and effective treatment for male and female pattern hair loss.

A structured search in PubMed and Google Scholar identified 864 records, with 32 articles meeting the inclusion criteria for review.

In a phase III, randomized, controlled trial, the efficacies of topical 0.25% w/w finasteride spray (1–4 sprays; 50–200 μl/day) and once‐daily finasteride 1 mg oral tablet were similar when administered for 24 weeks (mean change from baseline, 20.2 vs. 21.1 hairs/cm²). Additionally, a double‐blind, randomized trial compared the efficacies of twice‐daily finasteride 1% topical gel and once‐daily finasteride 1 mg oral tablet for 6 months, and found similar results in both groups. Moreover, a combination of topical minoxidil and topical finasteride may enhance efficacy.

Topical finasteride reduces both scalp and plasma DHT levels. In an open‐label pharmacodynamic study, a 7‐day treatment of twice‐daily finasteride 0.25% topical solution and once‐daily finasteride 1 mg oral tablet provided similar inhibition of plasma DHT.

Topical finasteride reduces the potential for systemic side effects, including the risk of sexual dysfunction. The side effects are localized to the application site, for example, scalp pruritus, burning sensation, irritation, contact dermatitis, and erythema.

Topical finasteride may be an alternative for those concerned about the oral formulation's systemic side effects.