Saw palmetto (Serenoa repens) is a palm native to the southeastern United States. Extracts of its berries are the world’s best-selling supplement for prostate health, taken by millions of men for urinary symptoms caused by an enlarged prostate (benign prostatic hyperplasia, or BPH).
The evidence, in brief
Early, smaller studies were encouraging, and some European countries have long used saw palmetto extracts. But when larger, better-designed trials were carried out, the picture changed:
- Large randomized trials in the United States found saw palmetto was no better than placebo at improving urinary symptoms, even at higher doses.
- A Cochrane systematic review concluded that saw palmetto on its own provides little to no improvement in urinary symptoms or urine flow compared with placebo.
Why do so many men feel it helps? BPH symptoms naturally come and go, and placebo effects in urinary symptom studies are large. That does not mean men are imagining improvements, but it does mean the supplement itself is unlikely to be the cause.
Is it safe?
Saw palmetto is generally well tolerated. Mild side effects include stomach upset and headache. It may slightly increase bleeding risk, so tell your doctor if you take blood thinners or have surgery planned.
Better-supported options
- See your doctor. Prescription medications for BPH are well studied and effective for many men, and your doctor can rule out other causes.
- Beta-sitosterol has older trial data showing improvements in symptom scores and flow, though the research is dated.
- Lifestyle measures help: reduce fluids before bed, cut back on caffeine and alcohol, and stay active.
Compare the options in our prostate supplement guide.
When to get checked urgently
See a doctor promptly if you notice blood in your urine or semen, pain when urinating, fever, or you suddenly cannot urinate at all.
Does saw palmetto lower PSA?
Research suggests it does not significantly change PSA levels, but always tell your doctor about any supplements before a PSA test.
Does saw palmetto cause hair loss or help it?
Saw palmetto is sometimes marketed for hair loss because of its proposed effect on DHT. Evidence for hair loss is limited and inconsistent.
Is saw palmetto in men’s multi-formulas worth it?
It is unlikely to hurt, but it is also not a reason to choose a product. Focus on the ingredients with stronger evidence for your goal.