Saw palmetto is a popular herbal medication and extract derived from the fruit of the low growing, small palm, Serenoa repens, which has fan shaped leaves and is native to Florida and the Southeast United States. Currently, saw palmetto is used mostly for symptoms of benign prostatic hypertrophy. Saw palmetto has been implicated in rare cases of clinically apparent liver injury, but its specific role in causing liver injury remains uncertain.


Saw palmetto (saw pal met’ toe) is a widely used herbal derived from the fruit of the low growing bushy palm of the same name (Serenoa repens). Native Americans used saw palmetto fruit both as a food as well as an herbal remedy with multiple uses, including as a sedative, diuretic, sleeping aid, expectorant and cough suppressant, aid to lactation, infertility, indigestion and urinary problems. Currently, saw palmetto is one of the most widely used herbal medications and is used largely for symptomatic benign prostatic hypertrophy. Saw palmetto is available in multiple formulations including liquid extracts, tablets, capsules, and as an herbal tea. The active components of palmetto extracts are believed to be the volatile oils and free fatty acids which have activity in inhibiting 5-alpha-reductase and the conversion of testosterone to dihydrotesterone, which has been demonstrated in vitro, but not in human studies. In short term clinical trials, saw palmetto appeared to be beneficial in improving symptoms of prostatic hypertrophy, but it had no effects on prostate size or serum prostatic specific antigen (PSA) levels. In longer term studies, the benefit of saw palmetto in improving urinary symptoms of benign prostatic hypertrophy was less clear. Saw palmetto is available in multiple over-the-counter preparations often in combination with other herbals or dietary supplements, and most commonly for symptoms of urinary hesitancy, urgency or burning. Side effects of saw palmetto are uncommon and mild and may include dizziness, headache, nausea, vomiting, constipation and diarrhea. In most randomized controlled clinical trials, side effects were no more frequent with saw palmetto than with placebo therapy.


Chronic therapy with saw palmetto has not been linked to serum enzyme elevations and prospective trials found little or no evidence of liver injury from its administration. However, there have been rare case reports of clinically apparent liver injury attributed to saw palmetto, although in some instances, other possible causes of liver disease were present. In the reported cases, the latency to onset was within 1 to 2 weeks of starting therapy, and clinical features resembled acute viral hepatitis with a hepatocellular pattern of serum enzyme elevations and resolution within 1 to 3 months. Immunoallergic and autoimmune features were not present.

Likelihood score: D (possible, rare cause of clinically apparent liver injury).

Mechanism of Injury

Saw palmetto extracts have many components, but none of them has been shown to be particularly hepatotoxic. The rare cases of liver injury reported with saw palmetto use have had idiosyncratic features. Saw palmetto has few herb-drug interactions and is not affected by inducers or inhibitors of the cytochrome P450 enzyme system.

Outcome and Management

Hepatotoxicity from saw palmetto is very rare and cases have been self-limiting upon stopping the herbal. There have been no instances leading to fatalities, liver transplantation, chronic hepatitis, or vanishing bile duct syndrome. Studies of rechallenge have not been reported.

Other Names: Cabbage palm, Sabal

Drug Class: Herbal and Dietary Supplements



Saw Palmetto – Generic


Herbal and Dietary Supplements


Fact Sheet at National Center for Complementary and Integrative Health, NIH



References updated: 02 April 2020

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    (Expert review of hepatotoxicity published in 1999; saw palmetto is not discussed).
  • Seeff L, Stickel F, Navarro VJ. Hepatotoxicity of herbals and dietary supplements. In, Kaplowitz N, DeLeve LD, eds. Drug-induced liver disease. 3rd ed. Amsterdam: Elsevier, 2013, pp. 631-58.
    (Review of hepatotoxicity of herbal and dietary supplements [HDS]; saw palmetto is listed as nonhepatotoxic).
  • Saw palmetto. In, PDR for Herbal Medicines. 4th ed. Montvale, New Jersey: Thomson Healthcare Inc. 2007: pp. 725-9.
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    (65 year old man developed jaundice and pruritus 2 weeks after starting an herbal preparation that contained saw palmetto [bilirubin 8.2 mg/dL, ALT 1364 U/L, Alk P 179 U/L, AMA positive, anti-HCV positive, HCV RNA negative], with resolution 3 months after stopping).
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    (Analysis of the adverse events that arose in a controlled trial of saw palmetto vs placebo in 369 men with symptoms of benign prostatic hypertrophy found no differences in rates of adverse events; ALT elevations occurred in 12-14% of saw palmetto vs 11-17% of placebo recipients).
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  • Vinarov AZ, Spivak LG, Platonova DV, Rapoport LM, Korolev DO. 15 years' survey of safety and efficacy of Serenoa repens extract in benign prostatic hyperplasia patients with risk of progression. Urologia. 2019;86:17–22. [PubMed: 29741118]
    (Among 30 patients with benign prostatic hypertrophy treated with saw palmetto [320 mg once daily] for up to 10 years, there was no progression of symptoms and no reported adverse side effects that could be attributed to the herbal supplement).
  • Ye Z, Huang J, Zhou L, Chen S, Wang Z, Ma L, Wang D, et al. Efficacy and safety of Serenoa repens extract among patients with benign prostatic hyperplasia in China: a multicenter, randomized, double-blind, placebo-controlled trial. Urology. 2019;129:172–9. [PubMed: 30880074]
    (Among 354 Chinese patients with benign prostatic hypertrophy treated with saw palmetto [160 mg] or placebo twice daily for 24 weeks, urinary symptoms and peak urinary flow improved more with the herb treatment, while adverse event rates were similar and there were no serious adverse events or mention of ALT elevations or liver related side effects).