Saw palmetto as a natural DHT blocker

What is the claim behind saw palmetto as a hair-loss treatment?

Extracts of the saw palmetto berry are reported to inhibit 5-alpha reductase, the same enzyme Finasteride targets, so the mechanism against pattern hair loss would in theory be similar. That is why it is marketed as a natural alternative, often to people who want an anti-androgen effect without taking a prescription drug.

What does the evidence actually support for saw palmetto and hair loss?

A small number of studies report modest improvement in hair, while a larger body of research in benign prostatic hyperplasia has been mixed, with larger trials generally disappointing. For hair specifically the evidence is thin and the studies are small, and no trial has compared it directly with Finasteride, so there is no basis for treating it as equivalent.

A small number of studies have reported modest improvement, and there is a larger literature in benign prostatic hyperplasia where results have been mixed and larger trials have generally been disappointing.

For hair specifically, the evidence is thin and the studies are small. No trial has compared saw palmetto directly with Finasteride, so there is no basis for calling either one stronger, and none for treating them as equivalent. Presenting it as a substitute overstates what is known.

Why is saw palmetto's dosing harder to standardise than Finasteride's?

Finasteride is a defined molecule at a defined dose, while saw palmetto is a plant extract whose composition varies with species, preparation and manufacturer, and supplements are not regulated to pharmaceutical standards in most markets. That variability makes results hard to reproduce and makes any given product's actual content uncertain.

What is the practical guidance for someone considering saw palmetto?

Tell your doctor and surgeon that you take saw palmetto, as you should with any supplement. A review of supplements and bleeding found no association between saw palmetto and bleeding, so this is about giving them a complete picture rather than a known surgical risk. Do not assume natural means free of effects: anything with a real anti-androgen action has real implications. Anything acting on androgens is generally avoided in pregnancy, and if you want that effect, discuss evidenced options instead.

• Tell your doctor and surgeon you take it, as you should with any supplement; the best available review found no link between saw palmetto and bleeding
• Do not assume natural means free of effects; anything with a real anti-androgen action has real implications
• Anything acting on androgens is generally avoided in pregnancy
• If you want an anti-androgen effect, discuss the evidenced options rather than substituting

The pharmaceutical alternatives are compared in our guide to slowing hair loss without surgery.

Sources

1. Bayne CW, Donnelly F, Ross M, Habib FK. Serenoa repens (Permixon): a 5alpha-reductase types I and II inhibitor-new evidence in a coculture model of BPH. The Prostate, 1999;40(4):232-241. pubmed.ncbi.nlm.nih.gov/10420151
2. Evron E, Juhasz M, Babadjouni A, Mesinkovska NA. Natural Hair Supplement: Friend or Foe? Saw Palmetto, a Systematic Review in Alopecia. Skin Appendage Disorders, 2020;6(6):329-337. pubmed.ncbi.nlm.nih.gov/33313047
3. Franco JV, Trivisonno L, Sgarbossa NJ, Alvez GA, Fieiras C, Escobar Liquitay CM, et al. Serenoa repens for the treatment of lower urinary tract symptoms due to benign prostatic enlargement. Cochrane Database of Systematic Reviews, 2023;6(6):CD001423. pubmed.ncbi.nlm.nih.gov/37345871
4. Barry MJ, Meleth S, Lee JY, Kreder KJ, Avins AL, Nickel JC, et al. Effect of increasing doses of saw palmetto extract on lower urinary tract symptoms: a randomized trial. JAMA, 2011;306(12):1344-1351. pubmed.ncbi.nlm.nih.gov/21954478
5. Bent S, Kane C, Shinohara K, Neuhaus J, Hudes ES, Goldberg H, et al. Saw palmetto for benign prostatic hyperplasia. The New England Journal of Medicine, 2006;354(6):557-566. pubmed.ncbi.nlm.nih.gov/16467543
6. Booker A, Suter A, Krnjic A, Strassel B, Zloh M, Said M, et al. A phytochemical comparison of saw palmetto products using gas chromatography and 1H nuclear magnetic resonance spectroscopy metabolomic profiling. Journal of Pharmacy and Pharmacology, 2014;66(6):811-822. pubmed.ncbi.nlm.nih.gov/24417505

This article summarises published research. It is general educational information, not medical advice, and it is not a recommendation to start, stop or change any medication. Prescription drugs carry contraindications and interactions; discuss them with a doctor who knows your medical history.