Toxicology of Saw Palmetto

Saw Palmetto extract, widely used to remedy for urinary dysfunction due to enlarged prostate (benign prostatic hyperplasia (BPH)), is generally regarded as safe with high long-term tolerability

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A randomized clinical trial (Avins et al., 2008) was performed among 225 men with moderate-to-severe symptoms of benign prostatic hyperplasia, comparing a standardized extract of Saw Palmetto berry (160 mg twice daily) with a placebo over a one-year period.

There were no significant differences observed between the Saw Palmetto and placebo-allocated participants in the risk of suffering at least one serious adverse event (5.4% vs. 9.7%, respectively; p = 0.31) or non-serious symptomatic adverse event (34.8% vs. 30.1%; p = 0.48). There were few significant between-group differences in sexual functioning or for most laboratory analyses, with only small differences observed in changes over time in total bilirubin (p = 0.001), potassium (p = 0.03), and the incidence of glycosuria (0% in the saw palmetto group vs. 3.7% in the placebo group, p = 0.05).

In another clinical study (Avins et al., 2012), a total of 369 patients were randomized in the Complementary and Alternative Medicine for Urological Symptoms (CAMUS) trial, of whom 357 were included in this modified intent to treat analysis. Participants were randomized to 320, 640 and 960 mg daily of an ethanolic saw palmetto extract or to an identical-appearing placebo in an escalating manner at 6-month intervals for a total of 18 months of follow-up.  Adverse event assessments, vital signs, and blood and urine laboratory tests were obtained at regular intervals.

There were no statistically significant differences between the groups in the rates of serious or non-serious adverse events, changes in vital signs, digital prostate examination findings or study withdrawal rates. Overall, there were no significant intergroup differences in laboratory test abnormalities, while differences in individual laboratory tests were rare and small in magnitude. No evidence of significant dose-response phenomena was identified.


  • Avins A, Bent S, Staccone S, Badua E, Padula A, Goldberg H, Neuhaus J, Hudes E, Shinohara K and Kane C. (2008).  A Detailed Assessment of A Saw Palmetto Extract. Complement Ther Med. June: 16(3): 147-154.
  • Avins A, Lee J, Meyers C, Barry M and the CAMUS Study Group. (2012). Safety and Toxicity of Saw Palmetto in the CAMUS Trial. J. Urol. pii: S0022-5347(12)05181-6.