Saw palmetto (Serenoa repens) is a small palm tree native to the West Indies and the southeast coast of North America whose berries are used in supplements. It is promoted mostly for urinary symptoms of an enlarged prostate (benign prostatic hyperplasia, BPH), and also for male-pattern hair loss and chronic prostatitis.
Also known as: Serenoa repens, Sabal serrulata, American dwarf palm.
Saw palmetto has no intake value or upper limit. NCCIH describes an NIH-funded trial that tested up to three times the usual dose without benefit for BPH symptoms. Products are berry extracts made in different ways (for example, with hexane), so amounts are not comparable across products. These are study protocols, not a recommendation.
It is sold in the US as a dietary supplement. Under the 1994 dietary supplement law (DSHEA), FDA does not approve dietary supplements before they are marketed, and the maker, not FDA, is responsible for safety and labeling. There is no FDA-approved saw palmetto drug.
A 2023 Cochrane review (Franco) of 27 studies with 4,656 men found that saw palmetto alone results in little to no difference in urinary symptoms or quality of life compared with placebo, short or long term (high-certainty evidence). NCCIH says two NIH-funded trials, including one using up to three times the usual dose, found no improvement, and hexane-extracted products did no better. A 2022 review found no significant benefit for chronic prostatitis, and evidence for hair loss is too limited for conclusions.
NCCIH says saw palmetto is well tolerated and has been used safely in studies for up to 3 years; side effects are mild and infrequent (digestive symptoms, dizziness, headache). It does not appear to affect PSA readings, even at higher amounts. It may be unsafe during pregnancy or breastfeeding.
We could not find a single published half-life or time to peak for saw palmetto that applies to a supplement dose, so we do not list one.
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