Topical Finasteride Clinical Trials: Summary of the Evidence
Medically reviewed by [Reviewer Name, MD] | Last reviewed: August 2026 | Editorial policy | Topical finasteride hub
This page summarizes the key clinical trials underpinning the evidence base for topical finasteride. Note: no FDA-approved topical finasteride formulation exists in the US as of 2026; all trials below studied compounded or proprietary formulations.
Trials Summary
| Trial | Design | n | Duration | Key Findings |
|---|---|---|---|---|
| Mazzarella et al., 1997 | RCT; topical fin 0.005% vs. oral fin 1 mg | 20 | 16 weeks | Both groups showed comparable hair growth improvements; topical had lower systemic DHT suppression |
| Caserini et al., 2016 | Two randomized pharmacodynamic studies; topical fin 0.25% solution | 50 | 1 week | At 100 to 200 µL daily, scalp DHT fell 47% to 52% and serum DHT 24% to 26%; hair growth was not measured |
| Piraccini et al., 2022 | Phase III; topical fin 0.25% spray vs. placebo; double-blind RCT | 458 | 24 weeks | Statistically superior to placebo on target area hair count; serum DHT reduced 34.5% (oral arm 55.6%); favorable safety profile at study dose |
Evidence Assessment
- The Piraccini 2022 Phase III trial is the largest and most rigorous; it supports efficacy vs. placebo at 24 weeks
- No trial has conducted a powered, long-term head-to-head comparison of topical vs. oral finasteride with 5+ year follow-up
- Formulation standardization is a key limitation: “topical finasteride” encompasses multiple concentrations, vehicles, and technologies; results from one formulation may not generalize to others
Full clinical context: Topical finasteride hub | Topical vs. oral comparison
Sources
- Piraccini BM, et al. “Efficacy and safety of topical finasteride spray solution for male androgenetic alopecia.” J Eur Acad Dermatol Venereol. 2022;36(2):286-294.
- Caserini M, et al. “Effects of a novel finasteride 0.25% topical solution on scalp and serum dihydrotestosterone in healthy men with androgenetic alopecia.” Int J Clin Pharmacol Ther. 2016;54(1):19-27.