Saw palmetto on its own does not relieve urinary symptoms from an enlarged prostate better than a placebo. A 2023 Cochrane review of 27 studies and two large NIH trials, one at triple the usual dose, found little to no benefit. It is well tolerated and does not change PSA readings.
Saw palmetto is the best-known supplement for prostate symptoms in the US. We read the latest Cochrane review, the two large NIH-funded trials and the federal guidance on enlarged prostate before writing this. The short version: for urinary symptoms caused by an enlarged prostate, saw palmetto on its own works about as well as a placebo.
| What it is | Extract from the berries of Serenoa repens, a small palm native to the southeast US[1] |
|---|---|
| Mainly sold for | Urinary symptoms of an enlarged prostate (BPH), hair loss, chronic prostatitis[1] |
| Standard trial dose | 320 mg a day[4] |
| Best evidence | 2023 Cochrane review: 27 studies, 4,656 men, little to no benefit on its own[2] |
| Safety | Well tolerated in studies up to 3 years; mild stomach upset, headache, dizziness[1] |
| Effect on PSA test | None found, even at 960 mg a day[5] |
| Avoid if | Pregnant or breastfeeding[1] |
What is saw palmetto?
Saw palmetto is a small palm tree, Serenoa repens, that grows 6 to 10 feet tall along the southeast coast of North America and in the West Indies. Supplements are made from its berries.[1]
It is sold mainly to men with urinary symptoms from an enlarged prostate, also called benign prostatic hyperplasia or BPH. It is also marketed for male pattern hair loss and chronic prostatitis. In 2006, researchers estimated that more than 2 million men in the US were using it.[3]
BPH itself is common. The National Institute of Diabetes and Digestive and Kidney Diseases says it affects 5 to 6 percent of men aged 40 to 64, and 29 to 33 percent of men aged 65 and older. It is not cancer and does not raise your risk of prostate cancer.[10][11]
Does saw palmetto help an enlarged prostate?
No, not on its own. The 2023 Cochrane review pooled 27 studies with 4,656 men. It found with high certainty that saw palmetto alone makes little to no difference to urinary symptoms, both after 3 to 6 months and after 12 to 17 months.[2]
The short-term difference was less than one point on a 35-point symptom scale. That is far smaller than the change most men would notice. The National Center for Complementary and Integrative Health now says saw palmetto is “probably not helpful” for BPH symptoms.[1]
The review also looked at products that mix saw palmetto with other herbs. Those showed a small possible benefit, but the evidence was low certainty, so no firm conclusion is possible.[2]
| Group | Drop in AUA symptom score |
|---|---|
| Saw palmetto | 2.20 |
| Placebo | 2.99 |
What did the biggest trials find?
Two large, placebo-controlled trials funded by the National Institutes of Health tested saw palmetto in American men. Neither found a benefit.[1]
| Trial | Who and how long | Dose | Result |
|---|---|---|---|
| STEP, 2006[3] | 225 men over 49 with moderate to severe symptoms, 1 year | 160 mg twice a day | No difference from placebo in symptoms, urine flow, prostate size or PSA |
| CAMUS, 2011[4] | 369 men aged 45 or older at 11 sites, 72 weeks | 320 mg, raised to 640 mg, then 960 mg a day | No better than placebo for any main or secondary outcome |
In STEP, the gap between saw palmetto and placebo on the symptom index was just 0.04 points. Peak urine flow, leftover urine in the bladder, quality of life and prostate size did not change either.[3]
CAMUS was designed to answer the obvious follow-up: maybe the dose was too low. It tripled the dose over 72 weeks. Symptom scores fell 2.20 points with saw palmetto and 2.99 points with placebo, a difference of 0.79 points in favour of placebo.[4]
Do higher doses or hexane-extracted products work better?
Higher doses do not. CAMUS went up to 960 mg a day, three times the standard dose, and found no benefit over placebo.[4]
Some brands promote hexane-extracted saw palmetto, sold in Europe as Permixon, as the form that works. The Cochrane reviewers analysed hexane-extracted products separately and found no difference in their effect on symptoms.[1][2] A 2021 network meta-analysis of 22 randomised trials and 8,564 patients reached the same view: neither type gave a clinically meaningful improvement.[7]
One 2018 review did report a benefit for Permixon, including 0.64 fewer trips to the bathroom at night. But it pooled observational studies with randomised trials and covered a single branded product, so we treat it as a contested signal rather than proof.[6]
Does saw palmetto affect PSA tests?
No. Saw palmetto does not appear to change PSA readings, even at higher than usual doses.[1] In the CAMUS men, PSA rose by 0.23 ng/mL on saw palmetto and 0.16 ng/mL on placebo. The difference was not statistically meaningful.[5]
That matters in two ways. Saw palmetto will not hide a rising PSA, which is good. But a label that promises to support healthy PSA levels is making a claim the research does not back.
PSA can rise for many reasons, including prostate cancer, BPH and prostatitis. A level above 4.0 ng/mL is generally considered abnormal, though some doctors use different cutoffs by age.[12] Your doctor should interpret your result, not a supplement company.
Is saw palmetto safe?
For most men, yes. Saw palmetto is well tolerated and has been used safely in research studies for up to 3 years. Side effects are mild and infrequent, and may include stomach upset, dizziness and headache.[1]
A systematic review of 40 published reports found adverse events were mild and similar to placebo. The most common were abdominal pain, diarrhoea, nausea, tiredness, headache, lower sex drive and a runny nose. Rare serious events appeared only in isolated case reports where the cause was unclear.[8]
In the Cochrane review, side effects were about as common with saw palmetto as with placebo.[2] “Well tolerated” is not the same as “worth taking”, though. A safe product that does not work still costs money and can delay a proper diagnosis.
Who should not take saw palmetto?
- Anyone who is pregnant or breastfeeding. Saw palmetto may be unsafe in pregnancy and while breastfeeding.[1]
- Anyone taking prescription medicine should check with a doctor or pharmacist first. Some herbs and medicines interact in harmful ways.[1]
- Men with new or worsening urinary symptoms who have not been checked. Symptoms can come from other conditions that need treatment.[10]
Does saw palmetto help hair loss or prostatitis?
The evidence is too thin to say. NCCIH says the evidence on hair loss is too limited to reach conclusions.[1] A 2020 review found only 5 randomised trials and 2 smaller studies, many using mixed products, and called for large high-quality trials.[9]
For chronic prostatitis and chronic pelvic pain, a 2022 review of 5 studies found no significant benefit.[1]
When should you see a doctor about urinary symptoms?
See a doctor about any new urinary symptoms before trying a supplement. Trouble starting, a weak stream, dribbling, getting up at night and urgency can all come from BPH, but they can also come from bladder problems, urinary tract infections, prostatitis or prostate cancer.[10][11]
Get medical help right away if you:[10]
- cannot urinate at all
- have painful, frequent, urgent urination with fever and chills
- see blood in your urine
- have great discomfort or pain in your lower abdomen and urinary tract
Some common medicines can make BPH symptoms worse, including cold medicines with decongestants or antihistamines, some antidepressants, tranquilisers and diuretics. Mention everything you take.[10]
What treatments do doctors use for an enlarged prostate?
Doctors start with the mildest option that controls your symptoms. For mild symptoms that may mean watchful waiting and lifestyle changes.[10]
When symptoms bother you, there are approved medicines that have been tested against placebo: alpha blockers, 5-alpha reductase inhibitors, phosphodiesterase-5 inhibitors, or an alpha blocker combined with a 5-alpha reductase inhibitor. If medicines are not enough, options include minimally invasive procedures, such as water vapour therapy or a prostatic urethral lift, and surgery.[10]
Unlike saw palmetto, these treatments have shown real effects in trials. Your doctor can weigh their side effects against your symptoms.
If you still want to try it, what should you look for on the label?
Some men try saw palmetto anyway, often while waiting for an appointment. If you do, read the label with the trial data in mind.
- A clear dose. Look for saw palmetto berry extract with its amount listed, such as 320 mg a day, the standard dose used in trials.[4] Higher is not better.
- No proprietary blend. Many prostate formulas list one total weight for several herbs. You cannot tell how much saw palmetto you get. Read our guide to reading a Supplement Facts label.
- No disease claims. A product that says it shrinks the prostate, lowers PSA or prevents cancer is making claims the research does not support, and supplements are not allowed to claim they treat disease.
- A quality seal. A USP, NSF or ConsumerLab seal shows the product contains what the label says. It does not show it works.
- Fair refund terms. Since the evidence is weak, buy only from sellers with a clear refund window and no hidden auto-ship.
Agree a trial period with your doctor, track your symptoms honestly, and stop if nothing changes.
Our verdict on saw palmetto
Saw palmetto is safe for most men, but the best evidence shows it does not relieve urinary symptoms from an enlarged prostate any better than a sugar pill. Higher doses and special extracts do not change that. It does not affect PSA, it does not prevent prostate cancer, and the hair-loss evidence is too weak to judge.
If urinary symptoms bother you, the most useful step is a visit to your doctor. Proven treatments exist, and a check rules out conditions that need attention. You can browse more on prostate health and men’s health, and see how we review supplements.
Sources
- Saw Palmetto: Usefulness and Safety. NCCIH, National Institutes of Health, updated April 2025.
- Serenoa repens for the treatment of lower urinary tract symptoms due to benign prostatic enlargement. Franco JVA et al., Cochrane Database of Systematic Reviews, 2023.
- Saw palmetto for benign prostatic hyperplasia (STEP trial). Bent S et al., New England Journal of Medicine, 2006.
- Effect of increasing doses of saw palmetto extract on lower urinary tract symptoms (CAMUS trial). Barry MJ et al., JAMA, 2011.
- Effect of saw palmetto on serum prostate specific antigen (CAMUS). Andriole GL et al., Journal of Urology, 2013.
- Efficacy and safety of hexanic lipidosterolic extract of Serenoa repens (Permixon). Vela-Navarrete R et al., BJU International, 2018.
- Clinical efficacy of Serenoa repens versus placebo versus alpha-blockers: network meta-analysis. Russo GI et al., European Urology Focus, 2021.
- Serenoa repens (saw palmetto): a systematic review of adverse events. Agbabiaka TB et al., Drug Safety, 2009.
- Natural hair supplement: friend or foe? Saw palmetto, a systematic review in alopecia. Evron E et al., Skin Appendage Disorders, 2020.
- Enlarged Prostate (Benign Prostatic Hyperplasia). NIDDK, National Institutes of Health, reviewed June 2024.
- Enlarged Prostate (BPH). MedlinePlus, National Library of Medicine, updated December 2023.
- Prostate-Specific Antigen (PSA) Test. National Cancer Institute.
Frequently asked questions
Does saw palmetto shrink the prostate?
No. In the NIH-funded STEP trial, a year of saw palmetto did not change prostate size compared with placebo, and the 2023 Cochrane review found little to no benefit for urinary symptoms.
How much saw palmetto should I take?
The standard dose in trials was 320 mg a day. The CAMUS trial raised it to 960 mg a day and still found no benefit over placebo, so taking more is not better. Ask your doctor first.
Can saw palmetto affect my PSA test?
No. Saw palmetto does not appear to change PSA readings, even at higher doses. In the CAMUS trial, PSA changes were about the same as with placebo.
Is saw palmetto safe to take every day?
For most men it is well tolerated and has been used safely in studies for up to 3 years. Mild stomach upset, headache and dizziness can happen. Avoid it if pregnant or breastfeeding.
Does saw palmetto help with hair loss?
The evidence is too limited to say. A 2020 review found only a handful of small studies, many using mixed products, and called for larger high-quality trials.
Grace Whitaker is the health editor at Health Forge Daily. She reads supplement labels line by line, checks each ingredient and dose against published research, and tracks refund policies and customer complaints before a product gets a verdict. She is not a doctor, so every review points readers back to their own physician for medical decisions.
This article is for general information and is not medical advice. Supplements are not evaluated by the FDA and are not intended to diagnose, treat, cure or prevent any disease. Check with your doctor before you start any supplement.