Saw Palmetto: What the Trials Found for Prostate and Hair

Saw palmetto is the berry of a small American palm, taken mainly for prostate symptoms and thinning hair. The 2023 Cochrane review of 27 trials and 4,656 men found little to no difference from placebo in urinary symptoms (high certainty); a pooled analysis of one extract type was positive, and the hair trials are small.^{1, 2, 3} One UK saw palmetto medicine is registered on traditional use for men diagnosed with an enlarged prostate; as a food supplement it has no authorised health claim.⁴ Urinary symptoms need a GP first.⁵ This is the saw palmetto page of the Wellgard men's health guide.

Evidence at a glance

• Trials: 27 randomised trials, 4,656 men, pooled by Cochrane in 2023; five randomised trials and two cohort studies of hair products, reviewed 2020.
• Largest trial cited here: 369 men aged 45 or over, 72 weeks, 320 mg a day rising to 960 mg.
• Strongest measured outcome: 0.64 fewer night-time trips to the toilet and 2.75 mL/s more flow than placebo, pooled from 27 studies of one hexane extract; one author works for its manufacturer.
• Not tested: saw palmetto in pregnancy or in children.

Sources checked on 13 October 2026.

What is saw palmetto, and how is it supposed to work?

Saw palmetto (Serenoa repens) is a low fan palm native to the south-eastern United States; products use extracts of its fruit.⁶ It is thought to inhibit 5-alpha-reductase, the enzyme that converts testosterone into DHT;⁷ in the large trials prostate size and PSA changed no more than on placebo, so its effect in the body is unclear.^{8, 9}

Should you see a GP before trying saw palmetto for prostate symptoms?

Yes. The NHS says to see a GP for difficulty peeing or needing to pee more often, and to get an urgent appointment or NHS 111 for blood in your pee, pain when peeing or being unable to pee; the symptoms "can sometimes be caused by other more serious conditions".⁵ Prostate cancer "often has no symptoms at first", and the NHS advises a check if symptoms "change, get worse, or do not feel normal".¹⁰ NICE asks clinicians to review medicines, "including herbal and over-the-counter medicines".¹¹ Zinc for men covers zinc and the prostate.

Does saw palmetto help an enlarged prostate? The trials, NICE and the UK register

The 2023 Cochrane review of 27 trials and 4,656 men found saw palmetto "results in little to no difference" in urinary symptoms against placebo (high certainty); one hexane extract's pooled analysis was positive.^{1, 2}

NICE recommendation 1.8.1, from 2010 (reviewed December 2024, update planned since August 2024), advises NHS clinicians: "Do not offer homeopathy, phytotherapy or acupuncture for treating LUTS in men" (lower urinary tract symptoms).¹¹ On the MHRA's traditional herbal registration list (27 October 2025), one 320 mg saw palmetto medicine is registered "for the relief of lower urinary tract symptoms in men who have a confirmed diagnosis" of an enlarged prostate, "based on traditional use only"; that wording belongs to the medicine, not to any food supplement.⁴ The European herbal medicines committee (2016) accepts the hexane extract on "well-established use" and the ethanol extract on traditional use, for adult men after a doctor excludes serious conditions; the reviews pooled different extracts and amounts, which is why it assesses the hexane extract separately. Pumpkin seed oil is asked about too.

Does saw palmetto help hair loss?

Small trials, the two newest run with the extracts' suppliers, reported less hair fall or more hair on saw palmetto products. The NHS calls finasteride and minoxidil "the main treatments for male pattern baldness", adds that "No treatment is 100% effective", and advises a GP if you're worried.¹⁴ A 2020 review found five randomised trials and two cohort studies of oral and topical products containing saw palmetto (100 to 320 mg), with results including a 27% rise in hair count; the reviewers wrote that "robust high-quality data are lacking".³ In a supplier-run 16-week trial of 80 adults, a daily capsule holding 100 mg of a saw palmetto oil cut hair fall by up to 29% from baseline and lowered blood DHT against placebo.¹⁵ In a six-month trial of 60 adults with self-perceived thinning, run with the extract's supplier, terminal hairs rose 18.6 on the extract and fell 10.1 on placebo.¹⁶ Biotin and zinc carry authorised wording: each contributes to the maintenance of normal hair.

Is saw palmetto safe? Side effects, liver and bleeding

Side effects were about as common as on placebo (12 trials, 2,399 men, moderate certainty), and mild in a 2009 review of 40 studies: chiefly stomach pain, diarrhoea, nausea, tiredness, headache, lower sex drive and a runny nose.^{1, 17} CAMUS found no evidence of toxicity at up to 960 mg a day over 18 months, with vital signs and blood and urine tests no different from placebo.¹⁸ In CAMUS sexual-function scores were no better than placebo; in the China trial erectile-function scores beat placebo.^{12, 13}

LiverTox (last updated 2 April 2020) rates saw palmetto a "possible, rare cause" of liver injury, with cases resolving on stopping, and lists a 2006 pancreatitis report;⁶ a 2026 case of cholestatic liver injury, in a 70-year-old on other medicines, showed yellow skin and eyes, itching and pale stools, signs that need a GP the same day.¹⁹ In 634 US adverse-event reports, haemorrhage was reported more often with aspirin (odds ratio 2.28) and at 75 or over (3.89): a question, not proof; tell your surgeon and pharmacist.²⁰ An Italian case series of people recruited online described persistent sexual and psychiatric symptoms, worse alongside finasteride; see a GP if mood or sexual function changes.⁷

How much saw palmetto did the trials use, and for how long?

Most urinary trials used 320 mg a day, as 160 mg twice a day in STEP;⁸ CAMUS reached 960 mg a day, the most we found, so no result covers 1,000 mg.¹² Hair trials used 100 to 320 mg of extract a day.^{3, 15, 16} Urinary outcomes were measured at 3 to 6 months and beyond a year, hair at 16 weeks to six months.^{1, 15, 16}

What we don't know

• Whether extract types differ: no placebo-controlled trial we read compared them directly.
• Whether the hair results hold in larger trials run independently of the extracts' makers.
• What saw palmetto contributes on its own to hair outcomes, the 2020 review's open question.³
• Whether it is safe in pregnancy, where we found no studies, and how far the 2026 case-series symptoms were caused by saw palmetto.

Frequently asked questions

Is it safe to take saw palmetto every day?

CAMUS gave it daily for 72 weeks at up to 960 mg without evidence of toxicity, and Cochrane found side effects about as common as on placebo.^{1, 18} Tell your GP you take it.

Is saw palmetto bad for the liver or kidneys?

LiverTox calls it a possible, rare cause of liver injury.⁶ CAMUS found blood and urine tests no different from placebo over 18 months; the records we read show no kidney injury signal, which is not a guarantee.¹⁸

What should you not take with saw palmetto?

Ask a pharmacist before combining it with aspirin, anticoagulants or hormone treatments, given the bleeding reports and the European adult-men-only position.²⁰ The 2009 review found no reported drug interactions.¹⁷

Can saw palmetto raise PSA levels?

Not in the trials: in CAMUS, PSA changed 0.23 ng/mL on saw palmetto and 0.16 on placebo, no significant difference; in STEP it did not differ.^{8, 9} Mention any supplement to the GP before a PSA test.

Can women take saw palmetto?

The hair trials above included women, but the European committee limits saw palmetto to adult men, and we found no pregnancy studies. A 2012 case report described hot flushes in an 11-year-old girl given it for hair loss.²¹ Women's hair loss is a GP question first.

Sources

1. Franco JV. Cochrane Database Syst Rev 2023. Systematic review of 27 randomised trials, 4,656 men. PubMed 37345871
2. Vela-Navarrete R. BJU Int 2018. Pooled analysis of 27 studies (15 randomised), about 5,800 men; one author employed by the extract's manufacturer. PubMed 29694707
3. Evron E. Skin Appendage Disord 2020. Systematic review of 5 randomised trials and 2 cohort studies. PubMed 33313047
4. MHRA. Herbal medicines granted a traditional herbal registration (THR), list dated 27 October 2025. gov.uk
5. NHS. Enlarged prostate. Page last reviewed 8 April 2025. nhs.uk
6. LiverTox: Saw palmetto. Database entry, last updated 2 April 2020. PubMed 31643699
7. Firenzuoli F. Br J Clin Pharmacol 2026. Case series, people recruited online. PubMed 41507085
8. Bent S. N Engl J Med 2006 (STEP). Randomised trial, 225 men, 12 months. PubMed 16467543
9. Andriole GL. J Urol 2013. PSA analysis of CAMUS, 369 men. PubMed 23253958
10. NHS. Symptoms of prostate cancer. Page last reviewed 31 July 2025. nhs.uk
11. NICE CG97. Lower urinary tract symptoms in men, recommendations 1.1.1 and 1.8.1. Guideline, 23 May 2010, updated 3 June 2015, reviewed 19 December 2024. nice.org.uk
12. Barry MJ. JAMA 2011 (CAMUS). Randomised trial, 369 men, 72 weeks. PubMed 21954478
13. Ye Z. Urology 2019. Randomised trial, 354 men, 24 weeks. PubMed 30880074
14. NHS. Hair loss. Page last reviewed 24 January 2024. nhs.uk
15. Sudeep HV. Clin Cosmet Investig Dermatol 2023. Randomised trial, 80 adults (20 per group), 16 weeks; supplier-run: four authors work for the extract's manufacturer; dose from the full text. PubMed 38021422
16. Ablon G. J Cosmet Dermatol 2026. Randomised trial, 60 adults, 180 days; no funding statement in the paper; registered with the extract's supplier as collaborator. PubMed 41652806
17. Agbabiaka TB. Drug Saf 2009. Systematic review of 40 studies. PubMed 19591529
18. Avins AL. J Urol 2013. Safety analysis of CAMUS, 357 men, 18 months. PubMed 23063633
19. Jayasree Rajendran R. Cureus 2026. Case report, one man. PubMed 42812739
20. Guo B. J Ethnopharmacol, online 21 July 2026. Pharmacovigilance analysis, 634 adverse-event reports. PubMed 42480876
21. Miroddi M. Pediatrics 2012. Case report, one girl. PubMed 23027164

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