Saw Palmetto
Saw palmetto supplements are promoted for prostate urinary symptoms and male-pattern hair loss. NCCIH says they are probably not helpful for prostate symptoms, and the evidence for hair loss is too limited to draw conclusions.
Saw palmetto is a small palm tree native to the southeastern United States and West Indies, whose berries are used in dietary supplements. It is most widely promoted for urinary symptoms associated with benign prostatic hyperplasia (BPH) and for male-pattern hair loss. NCCIH says we know enough to conclude that saw palmetto is probably not helpful for urinary symptoms from an enlarged prostate, and that the evidence for hair loss is too limited to draw conclusions. MSK notes adverse effects are generally mild and similar to placebo.
Where to get it
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Research & evidence
Strong support Some support Weak or no supportColours show how well the sources back each point. The reason is next to each one.
NCCIH says we know enough to conclude that saw palmetto is probably not helpful for urinary symptoms associated with an enlarged prostate gland.
Not supported by current evidenceWeak or no support. Trials found no clear benefit
Study details
NCCIH: "We know enough to conclude that saw palmetto is probably not helpful for this purpose." NCCIH: "Saw palmetto is promoted as a dietary supplement for urinary symptoms associated with an enlarged prostate gland ..."
Source: NCCIH, Saw Palmetto (Last Updated April 2025), How Much Do We Know?; NCCIH, Saw Palmetto (Last Updated April 2025), Background View source
A few small studies have tested saw palmetto, used orally or topically (applied to the scalp), for male-pattern hair loss. The evidence is too limited to allow conclusions to be reached.
Limited evidenceSome support. Based on one or a few small trials
Study details
NCCIH: "A few small studies have tested saw palmetto, used orally or topically (applied to the scalp), for male-pattern hair loss." NCCIH: "The evidence is too limited to allow conclusions to be reached."
Source: NCCIH, Saw Palmetto (Last Updated April 2025), What Have We Learned?; NCCIH, Saw Palmetto (Last Updated April 2025), What Have We Learned? View source
There is not enough evidence to determine whether saw palmetto is useful for other health purposes. More studies are needed before definitive conclusions can be made.
Limited evidenceSome support. Reviewers rated the certainty low
Study details
NCCIH: "There is not enough evidence to determine whether saw palmetto is useful for other health purposes." NCCIH: "More studies are needed before definitive conclusions can be made."
Source: NCCIH, Saw Palmetto (Last Updated April 2025), How Much Do We Know?; NCCIH, Saw Palmetto (Last Updated April 2025), How Much Do We Know? View source
Dosage
| Form | Amount |
|---|---|
| Any form | Whole berries are not standardised and are not the form studied. Use only liposterolic (lipid/sterol) standardised extracts. |
| Capsule | 320 mg/day of standardised liposterolic extract (lipid/sterol fraction), commonly as a single dose or split into two 160 mg doses. |
Side effects
Saw palmetto is generally well tolerated. Side effects are mild and infrequent and may include digestive discomfort, dizziness, and headache. It may increase bruising and bleeding risk. Avoid during pregnancy or breastfeeding.
Well documented Reported (case reports, anecdotal or one study) None reportedThe circle shows how well documented an effect is, not how serious it is. A rarely reported effect can still be serious, so always read ‘When to stop’.
| Effect | Frequency | When to stop |
|---|---|---|
| Digestive symptomsWell documentedListed plainly by NIH, MSK or LiverTox | Mild and infrequent | Stop and talk to a doctor if you notice any unexpected or concerning symptoms. |
| DizzinessWell documentedListed plainly by NIH, MSK or LiverTox | Mild and infrequent | Stop and talk to a doctor if you notice any unexpected or concerning symptoms. |
| HeadacheWell documentedListed plainly by NIH, MSK or LiverTox | Mild and infrequent | Stop and talk to a doctor if you notice any unexpected or concerning symptoms. |
Safety & interactions
Safety
NCCIH says saw palmetto is well tolerated and has been used safely in research studies for up to 3 years. It says adverse effects are mild and infrequent, and may include digestive symptoms, dizziness, and headache. MSK says most effects are reported as mild and similar to effects with placebo, and that saw palmetto may increase the risk of bruising and bleeding. NCCIH says that if you take any type of medicine, talk with your health care provider before using any herbal product, because some herbs and medicines interact in harmful ways.
Contraindications
NCCIH says saw palmetto may be unsafe for use during pregnancy or while breastfeeding. See Drug interactions for medicines to ask about.
Drug interactions
MSK says saw palmetto may have additive anticoagulant effects, according to case reports.
MSK says saw palmetto inhibits UGT enzymes in vitro and can increase the side effects of drugs metabolized by them.
Established: stated plainly by an authoritative source. Documented: supported by case reports or trial data. Theoretical: based on mechanism, animal data, or a cautious listing. Always check with your pharmacist or prescriber.
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