Encyclopedia · botanical
Saw palmetto
A berry extract with weak DHT-blocking activity that shows small benefits in short, mostly industry-linked trials and clearly less than finasteride in the one head-to-head.
What it is
An extract of the fruit of the dwarf palm Serenoa repens, sold as an oral supplement (typically lipid-rich extracts) and in topical products. It is also used for prostate symptoms. It is a supplement in the US, EU and UK and is not an approved hair treatment.
How it works
- In cultured human dermal papilla cells, a proprietary extract inhibited 5-alpha-reductase (IC50 0.39 micrograms/mL vs 29.1 for a commercial extract), and in ex-vivo follicles it prolonged the growth phase independently of testosterone. This is company-linked lab work. Broadley 2026
- In one 16-week trial, oral saw palmetto oil lowered serum DHT versus placebo (p<0.001), but the study was funded and run by the extract maker. Sudeep 2023
What the studies show
- Head to head (100 men, 24 months, open label): saw palmetto 320 mg/day vs finasteride 1 mg/day. Hair growth increased in 38% on saw palmetto vs 68% on finasteride. Rossi 2012
- Systematic review (7 studies): positive effects were reported (density up in 83% of patients in one study), but the authors say high-quality data are lacking and many products were blends, so saw palmetto's own contribution is unclear. Evron 2020
- Placebo-controlled (80 people, 16 weeks): hair fall fell by up to 29% (oral) and 22% (topical) from baseline, and density rose 5.2% (oral) and 7.6% (topical); the growth-phase ratio did not change. Manufacturer employees were among the authors. Sudeep 2023
- Proprietary extract (60 people, 180 days, placebo-controlled): terminal hair count rose 18.6 vs fell 10.1 on placebo (p<0.001), with no treatment-related adverse events; single author and an industry product. Ablon 2025; Ablon 2026
- Network meta-analysis (19 trials, 1,658 people): saw palmetto scored better than placebo on blinded doctor assessment, but certainty was low and trials varied. Zhou 2026
Side effects and safety
- Trials reported no serious adverse events. Evron 2020
- Because it may lower DHT, treat it as a drug-like supplement: avoid it in pregnancy and check with a clinician if you already take finasteride, dutasteride or hormonal therapy (a precaution, not trial-tested).
- Whether it produces the same sexual side-effect signal as finasteride is not established.
Bottom line
The evidence is small, short and mostly industry-run. It is a reasonable low-risk add-on for men or women who decline drugs, but expect a modest effect at best, and do not use it instead of finasteride or minoxidil when you need real regrowth. Doses and extracts vary a lot between products. Discuss with a doctor.
Studies 7
Evron E et al. Saw palmetto, a systematic review in alopecia. Skin Appendage Disord. 2020
Tested: saw palmetto-containing products, 100-320 mg
Result: Positive effects reported (for example density up in 83% of patients in one study); the authors say high-quality data are lacking and many products were blends.
Read the study ↗Rossi A et al. Finasteride 1 mg daily administration vs Serenoa repens 320 mg in male androgenetic alopecia: two-year study. Int J Immunopathol Pharmacol. 2012
Tested: Serenoa repens 320 mg/day vs finasteride 1 mg/day
Result: Hair growth increased in 38% on saw palmetto vs 68% on finasteride.
Read the study ↗Sudeep HV et al. Standardized saw palmetto oil in androgenetic alopecia: 16-week randomized controlled trial. Clin Cosmet Investig Dermatol. 2023
Tested: oral or topical standardised saw palmetto oil vs placebo (manufacturer-funded)
Result: Hair fall fell by up to 29% (oral) and 22% (topical); density rose 5.2% (oral) and 7.6% (topical); serum DHT fell with oral use; anagen/telogen ratio unchanged.
Read the study ↗Ablon G. Saw palmetto fatty acids extract: 90-day results. J Cosmet Dermatol. 2025
Tested: proprietary saw palmetto extract vs placebo (NCT06920758)
Result: Interim results of a randomised double-blind placebo-controlled trial of an industry product.
Read the study ↗Ablon G. Saw palmetto extract: 180-day results. J Cosmet Dermatol. 2026
Tested: proprietary saw palmetto extract (40) vs placebo (20)
Result: Terminal hair count rose 18.6 vs fell 10.1 on placebo (p<0.001); no treatment-related adverse events; single author, industry product.
Read the study ↗Broadley D et al. Lipidosterolic Serenoa repens extract in hair follicle organ culture. Int J Cosmet Sci. 2026
Tested: proprietary saw palmetto extract
Result: Inhibited 5-alpha-reductase (IC50 0.39 vs 29.1 micrograms/mL for a commercial extract) and prolonged anagen independently of testosterone; company-linked.
Read the study ↗Show 1 more studies
Zhou L et al. Dietary supplements in androgenetic alopecia: systematic review and network meta-analysis. Front Nutr. 2026
Tested: dietary supplements vs placebo or conventional treatments
Result: Saw palmetto extract scored better than placebo or conventional treatments on blinded doctor assessment and pumpkin seed oil improved density vs placebo; low-certainty, heterogeneous.
Read the study ↗Related
- Beta-sitosterolA plant sterol credited with weak anti-DHT activity, but no hair trial has tested it on its own.
- Pumpkin seed oilA food oil with two small randomised trials for pattern hair loss that look promising but are short, single-centre and unreplicated.
- FinasterideA prescription pill (and in some countries a scalp spray) that lowers DHT and is the best-proven drug for stopping male pattern hair loss.
- DutasterideA stronger cousin of finasteride that blocks both forms of the DHT-making enzyme and grew more hair than finasteride in head-to-head trials.
- Antiandrogen comparison for hair lossA side-by-side of the drugs, topicals and supplements that work on the androgen pathway, with who they were studied in and how strong the evidence is.