Botanicals & Herbs

Saw Palmetto

Also known as: Serenoa repens, Saw palmetto extract, Permixon

The prostate herb — popular for decades, but large well-run trials found no meaningful benefit for urinary symptoms.

By IngredientWiki Editorial Team
Fact-checked by IngredientWiki Editorial Team
Updated 2026-09-26
2 min read

In short

Saw palmetto is an extract from the berries of Serenoa repens, a small palm native to the southeastern US, traditionally used for urinary and reproductive health. It became one of the best-selling prostate supplements, but the evidence has not aged well: older small trials suggested mild benefit, while large, rigorous NIH studies found it no better than placebo for benign prostatic hyperplasia symptoms. It remains safe and still widely used.

Berry extract of the saw palmetto palm, native to Florida and the Southeast
Marketed for prostate and urinary symptoms
Largest trials (NIH-funded): no better than placebo for BPH
Generally safe; may interact with blood thinners

What is Saw Palmetto?

Saw palmetto's story is a lesson in supplement science. For decades, small European studies suggested it eased the weak stream and frequent nighttime urination of benign prostatic hyperplasia (BPH), and the berry extract outsold most prostate medications. Then the largest, best-controlled trial ever run — 369 men over 72 weeks — found saw palmetto indistinguishable from placebo. The extract is safe and its users are loyal, but the modern evidence base says: save your money, see a urologist.

Where it comes from

Natural sources

Berries of Serenoa repens, a dwarf palm of the southeastern US
Traditionally used by Seminole communities and early American physicians
Harvested wild in Florida; now cultivated

How it's made

Supplements use lipid extracts of the berries, standardized to fatty acids and plant sterols (85–95%).

What it does in products

Benefits

BPH urinary symptoms

strong evidence

The verdict is largely negative: the NIH CAMUS and STEP trials found saw palmetto no better than placebo for urinary flow, nighttime urination, or quality of life.

Prostate size and PSA

strong evidence

No consistent effect on prostate size or PSA levels in well-controlled studies.

Hair loss

emerging evidence

Some in-vitro evidence suggests weak 5-alpha-reductase inhibition, but no quality human trials support saw palmetto for male-pattern hair loss.

Side effects & safety

Mild stomach upset and headache (uncommon)Generally well tolerated in trials.

Possible bleeding risk (rare)Case reports suggest caution with anticoagulants and before surgery.

Safety considerations

Not applicable to women (hormonal activity); avoid use in pregnancy.
Possible additive bleeding with warfarin and antiplatelet drugs.
May theoretically interact with hormonal medications.
Not for: Pregnancy and breastfeeding
Not for: Planned surgery (stop 2 weeks prior)

How it's used

In supplements

Standard studied dose: 320 mg of lipid extract daily (often as 160 mg twice daily). Given the negative large trials, men with urinary symptoms should see a urologist rather than self-treat.

Regulatory status

Dietary supplement under DSHEA; in several European countries, saw palmetto extracts are licensed medicines for BPH — a regulatory divergence from the negative US trial results.

Why the trials turned negative

The early positive saw palmetto studies were small, short, and mostly industry-linked. The NIH then funded two rigorous trials — CAMUS and STEP — with dose escalation, placebo controls, and objective measurements. Both found no difference from placebo on any urinary endpoint. The episode became a textbook example of how larger, better studies can overturn a supplement consensus.

Frequently asked questions

Does saw palmetto actually work for prostate symptoms?

The best evidence says no. Two large NIH-funded trials found no benefit over placebo for urinary symptoms. If you have BPH symptoms, prescription options (alpha blockers, 5-ARIs) have far stronger evidence.

Does saw palmetto lower PSA or hide prostate cancer?

Saw palmetto does not meaningfully lower PSA, so it is unlikely to mask cancer screening — unlike finasteride, which does. That is reassuring for screening, but not a reason to take it.

Is saw palmetto safe?

Yes — it is well tolerated at standard doses, with mild GI side effects. The main cautions are theoretical bleeding interactions with blood thinners and avoiding it before surgery.

The bottom line

Saw palmetto is a safe supplement with a shrinking evidence base: the largest, best studies found no benefit for prostate symptoms. Men with BPH symptoms get more from a urologist visit than from this berry.

References

Saw Palmetto. NCCIH (National Institutes of Health). https://www.nccih.nih.gov/health/saw-palmetto
Saw palmetto for BPH (STEP trial). JAMA (PubMed). https://pubmed.ncbi.nlm.nih.gov/21954478/
Saw palmetto and BPH — literature search. PubMed (National Library of Medicine). https://pubmed.ncbi.nlm.nih.gov/?term=saw+palmetto+benign+prostatic+hyperplasia+randomized
Serenoa repens compound records. PubChem (National Library of Medicine). https://pubchem.ncbi.nlm.nih.gov/#query=Serenoa%20repens