By age 60, about half of men have an enlarged prostate, a condition doctors call benign prostatic hyperplasia, or BPH. It is not cancer, but it can make life frustrating: getting up at night to urinate, a weak stream, and the feeling that your bladder never quite empties.
Saw palmetto, made from the berries of a small palm that grows in the southeastern United States, is the most popular herbal remedy for these symptoms. It has been tested in some of the largest and best-designed trials of any herb, which means we can give a clear answer. Short version: in the best trials, saw palmetto did not work better than a placebo, even at triple the usual dose.
Saw palmetto at a glance: how strong is the evidence?
- 🚽 Urinary symptoms from BPHStrong evidence it does not beat placebo
- 📈 Higher dosesTested up to triple dose, still no benefit
- 🧑🦲 Hair lossSmall, low-quality studies only
- ✅ SafetyGenerally well tolerated
- 💊 Prescription optionsStrong evidence, ask your doctor
🌴 Why saw palmetto seemed promising
In the lab, saw palmetto extract partly blocks 5-alpha-reductase, the enzyme that converts testosterone into DHT, the hormone that drives prostate growth. Finasteride, a proven prescription drug for BPH, works on the same enzyme. Early European trials looked positive, which is how saw palmetto became so popular.
📊 What the big trials found
The STEP trial (2006). Published in the New England Journal of Medicine, this study gave 225 men with moderate to severe BPH symptoms either 160 mg of saw palmetto twice a day or a placebo for a full year. There was no difference between the groups in urinary symptom scores, urine flow, prostate size or quality of life.
The CAMUS trial (2011). Critics argued that the dose in STEP was too low, so an NIH-funded trial published in JAMA raised it. 369 men took saw palmetto at 320 mg a day, then 640 mg, then 960 mg, three times the standard dose, over 72 weeks. Saw palmetto was still no better than placebo at any dose.
The Cochrane reviews. In 2012, Cochrane reviewers pooled 32 randomized trials involving 5,666 men and concluded that saw palmetto did not improve urinary flow or symptoms compared with placebo, even at double or triple doses. An updated review in 2023 reached a similar conclusion: little to no improvement in symptoms or quality of life.
Our read: the early positive results came from smaller, shorter trials. When the question was tested properly, the benefit disappeared. That does not mean men who feel better on saw palmetto are imagining it. Prostate symptoms naturally go up and down, and the placebo response in BPH trials is large.
🧑🦲 What about hair loss?
Because of its effect on DHT, saw palmetto is also sold for male pattern hair loss. The studies are small, short and mostly low quality, so there is not enough evidence to recommend it. Minoxidil and finasteride have much stronger evidence.
🩺 See a doctor first, every time
Urinary symptoms in men are not always BPH. They can also come from infections, bladder problems, diabetes, medicines and, less often, prostate cancer. Before trying any supplement, it is worth seeing your doctor, who may check your urine, examine your prostate and talk with you about a PSA blood test.
If it is BPH, there are treatments with strong evidence:
- Alpha-blockers such as tamsulosin relax the prostate and bladder neck and often help within days.
- 5-alpha-reductase inhibitors such as finasteride shrink the prostate over months.
- Lifestyle steps, like cutting fluids two hours before bed, limiting caffeine and alcohol, and “double voiding”, help many men with milder symptoms.
- Minimally invasive procedures are options when medicines are not enough.
See a doctor promptly if you have blood in your urine, pain, fever, or you suddenly cannot urinate.
⚠️ Safety
According to NCCIH, saw palmetto appears to be well tolerated by most men. Mild stomach upset and headache are the most common side effects. In the CAMUS trial, it did not change PSA levels, so it should not interfere with prostate cancer screening. It is not for women who are pregnant or might become pregnant, because of its hormonal effects.
If you still want to try saw palmetto
Hawaii Pharm makes an alcohol-free liquid saw palmetto berry extract. Use it alongside a check-up, not instead of one, and tell your doctor you are taking it.
Affiliate link. We may earn a commission if you buy, at no extra cost to you. Price and availability are set by the retailer and can change.
🔍 Why do some men swear by it?
If saw palmetto does not beat a placebo, why do so many men say it helps? Three reasons stand out. First, BPH symptoms naturally come and go, and men often start a supplement when symptoms are at their worst, so some improvement would happen anyway. Second, the placebo response in prostate trials is large: in the CAMUS trial, men taking the dummy pill also reported fewer symptoms. Third, starting a supplement often comes with other changes, such as drinking less in the evening or cutting back on coffee, which do help.
None of that means those men are wrong about feeling better. It means the improvement is unlikely to come from the saw palmetto itself.
🏷️ If you decide to try it
- Look for the berry extract, usually labeled Serenoa repens.
- Know the dose. Trials used 320 mg a day of a fat-soluble extract, and up to 960 mg. Liquid extracts are measured differently, so follow the label.
- Keep a symptom diary for two weeks before you start and for three months after, so you can judge honestly.
- Keep your check-ups. A supplement should never delay a visit to your doctor.
Frequently asked questions
Does saw palmetto prevent prostate cancer?
There is no good evidence that it does.
Is a combination prostate formula better?
Multi-ingredient formulas are much less studied than saw palmetto alone. Read the label and check each ingredient with your pharmacist, especially if you take blood thinners.
How long would it take to know if it works?
The major trials ran for one year or longer. If you try it, give it a few months and track your symptoms with a simple diary, such as how many times you get up at night.
The honest bottom line
Saw palmetto has been tested in some of the largest trials of any herbal supplement, and in the best of them it worked no better than a placebo, even at triple the usual dose. It is generally safe, but it should never replace a check-up, because urinary symptoms can have other causes. Proven treatments for BPH are effective and worth discussing with your doctor.
Studies and sources
- Bent S et al. (2006). Saw palmetto for benign prostatic hyperplasia. New England Journal of Medicine, via PubMed.
- Barry MJ et al. (2011). Effect of increasing doses of saw palmetto extract on lower urinary tract symptoms: a randomized trial. JAMA, via PubMed.
- Tacklind J et al. (2012). Serenoa repens for benign prostatic hyperplasia. Cochrane Database of Systematic Reviews, via PubMed.
- Franco JV et al. (2023). Serenoa repens for the treatment of lower urinary tract symptoms due to benign prostatic enlargement. Cochrane Database of Systematic Reviews, via PubMed.
- Saw palmetto. NCCIH.
This article is for general education and is not medical advice. Talk to your doctor or pharmacist before starting a supplement, especially if you take medication or have a health condition. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
