Does Saw Palmetto Work for an Enlarged Prostate? Large Trials Say It Matches Placebo
A Cochrane review of 27 trials and two large North American trials, one at triple the usual dose, found saw palmetto no better than placebo for urinary symptoms.
By Kymata Health Editorial Published Last checked
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Key takeaways
From 6 sources- Urinary symptoms such as a weak stream or frequent night-time urination can come from prostate cancer as well as an enlarged prostate, so get them checked by a clinician before relying on a supplement5.
- A 2023 Cochrane review of 27 trials (4,656 men; 19 tested saw palmetto alone) found the herb alone made little to no difference to urinary symptoms or quality of life, with high-certainty evidence1.
- In a 1-year trial of 225 men, 320 mg a day did no better than placebo on symptom scores, urine flow, prostate size or PSA2.
- Raising the dose to 960 mg a day over 72 weeks did not help either: symptom scores fell slightly more with placebo3.
- Side effects were mild and similar to placebo in the trials and in a review of safety reports14.
- Ten of the 27 Cochrane trials were funded by the pharmaceutical industry, two by government agencies, and the rest did not state funding1.
What this article covers
1 evidence profileThe evidence, graded
Pulled from the trial tables in our evidence profiles. Grades follow our evidence-grading policy.
Graded findings
3 rows- ∅No effectUrinary symptoms from benign prostatic enlargementNo effect Little to no difference vs placebo in IPSS symptom scores at 3–6 months (MD −0.90 points on a 0–35 scale, high certainty) and at 12–17 months (MD 0.07), and in quality of life. Adverse events similar to placebo.Saw palmetto · Systematic review · n=4,656 · 2023 · PMID 37345871
- ∅No effectProstate symptoms and urine flowNo effect No difference vs placebo in AUA symptom score, peak urine flow, prostate size, residual volume, quality of life or PSA. Side-effect rates were similar.Saw palmetto · RCT · n=225 · 2006 · PMID 16467543
- ∅No effectLower urinary tract symptoms at increasing dosesNo effect Symptom scores fell 2.20 points with saw palmetto and 2.99 points with placebo; no secondary outcome favoured saw palmetto. No clearly attributable adverse effects.Saw palmetto · RCT · n=369 · 2011 · PMID 21954478
Where these trials agree: Saw palmetto and prostate, counted row by row in the Consensus finder.
The Cochrane review
The 2023 Cochrane update included 27 randomized trials and 4,656 men, mostly over 50 with moderate symptoms; 19 trials compared saw palmetto alone with placebo and 8 tested combination products1. Ten trials were funded by the pharmaceutical industry, two by government agencies, and the rest did not state funding1.
In low-risk-of-bias trials, the symptom score difference at 3 to 6 months was 0.90 points on a 0 to 35 scale, which the authors rated as little to no difference with high certainty1. At 12 to 17 months the difference was 0.07 points1.
Combination products that pair saw palmetto with other herbs had less certain results, with low-certainty evidence1.
Two large North American trials, standard and triple dose
The STEP trial gave 225 men over 49 with moderate-to-severe symptoms 160 mg twice a day or placebo for 1 year2. Symptom scores, peak urine flow, prostate size, leftover urine after voiding, quality of life and PSA did not differ from placebo2.
The CAMUS trial asked whether higher doses would help3. It enrolled 369 men aged 45 or older at 11 sites in the US and Canada and raised the dose from 320 to 640 and then 960 mg a day at 24 and 48 weeks3. Over 72 weeks, symptom scores fell 2.20 points with saw palmetto and 2.99 points with placebo, and no secondary outcome favoured the extract3.
Safety and who should be careful
A systematic review of 40 studies and safety reports found side effects were mild and similar to placebo, most often stomach pain, diarrhoea, nausea, fatigue, headache, lower libido and runny nose4. It found no reported drug interactions, which means none were documented rather than proof that none exist4.
Groups that should talk to a clinician first:
- Men with new or worsening urinary symptoms: NIDDK advises discussing any urinary symptoms with a health care professional, because some can be caused by bladder problems, infections, prostatitis or prostate cancer5. The trials found no benefit over placebo, so relying on the herb can delay that evaluation12.
- Men having PSA tests: PSA is used to screen for prostate cancer, so a supplement that lowered it could mask a warning sign. NCCIH says saw palmetto does not appear to affect PSA readings, even at higher-than-usual amounts, and PSA did not differ from placebo in STEP62. Tell whoever orders the test about any supplements you take.
- Men on prostate or hormone medicines: interaction data are limited to an absence of reports4.
- Anyone who notices lower libido, one of the reported side effects4.
- Pregnancy and breastfeeding: NCCIH says saw palmetto may be unsafe6.
Quick answers
Common questions
3 answersDoes saw palmetto lower PSA?
Would a higher dose work better?
The CAMUS trial tested up to 960 mg a day and found no benefit over placebo3.
Keep reading
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Saw palmetto products from partner brands
3 products Paid links · we earn a commission- Quick pickBotanic ChoiceBotanic Choice Saw Palmetto, 500 mg, 90 capsules
1 capsule: 500 mg saw palmetto berry powder (whole berry, not a standardized extract); label directions 1 capsule 3 times daily
$22.00one-timeChecked Oct 12, 2026 - SupersmartSaw Palmetto Supplement5% off with the Supersmart newsletterGet 5% off with the newsletter (paid link, opens in new tab)
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1 softgel: 320 mg saw palmetto oil extract standardized to 85% fatty acids; 30 servings
$18.00one-time$15.30subscribeChecked Oct 11, 2026 - Dr. TobiasDr. Tobias Saw Palmetto (90 capsules)
Per serving: 500 mg saw palmetto standardized to a 45% extract; 90 capsules, 30 servings
$9.99one-timeChecked Oct 14, 2026
References
6 sources. Numbers in the text link here.
Sources cited in this article
6 sources- 1Serenoa repens for the treatment of lower urinary tract symptoms due to benign prostatic enlargementCochrane Database Syst Rev, 2023 · PMID 37345871
- 2Saw palmetto for benign prostatic hyperplasiaN Engl J Med, 2006 · PMID 16467543
- 3Effect of increasing doses of saw palmetto extract on lower urinary tract symptoms: a randomized trialJAMA, 2011 · PMID 21954478
- 4Serenoa repens (saw palmetto): a systematic review of adverse eventsDrug Saf, 2009 · PMID 19591529
- 5Enlarged Prostate (Benign Prostatic Hyperplasia)National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), 2024
- 6Saw Palmetto: Usefulness and Safety (Last Updated: April 2025)National Center for Complementary and Integrative Health (NCCIH), 2025
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