Saw Palmetto

ByLaura Shane-McWhorter, PharmD, University of Utah College of Pharmacy
Reviewed/Revised Jan 2023
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Serenoa repens, Serenoa serrulata) berries contain the plant’s active ingredients. The active ingredients, thought to be fatty acids, seem to inhibit 5-alpha-reductase, thus opposing the conversion of testosterone

(See also Overview of Dietary Supplements and National Institutes of Health (NIH): Saw palmetto.)






Adverse Effects

Headache and diarrhea may occur, but few serious adverse effects have been reported.



Drug Interactions


estrogens in oral contraceptives or hormone replacement therapy and decrease their benefit.

(See also table Some Possible Dietary Supplement–Drug Interactions.)


  1. 1. Barry MJ, Meleth S, Lee JY, et al; Complementary and Alternative Medicine for Urological Symptoms (CAMUS) Study GroupJAMA 306(12):1344-1351, 2011. doi: 10.1001/jama.2011.1364

  2. 2. Tacklind J, Macdonald R, Rutks I, et al: Serenoa repens for benign prostatic hyperplasia. Cochrane Database Syst Rev 12:CD001423, 2012. doi: 10.1002/14651858.CD001423.

  3. 3. Vela-Navarrete R, Alcaraz A, Rodriguez-Antolin A, et al: Efficacy and safety of a hexanic extract of Serenoa repens (Permixon®) for the treatment of lower urinary tract symptoms associated with benign prostatic hyperplasia (LUTS/BPH): systematic review and meta-analysis of randomised controlled trials and observational studies. BJU Int 10.1111/bju.14362, 2018. doi: 10.1111/bju.14362

  4. 4. Cai T, Cui Y, Yu S, et al: Comparison of serenoa repensAm J Mens Health 14(2):1557988320905407, 2020. doi:10.1177/1557988320905407

  5. 5. Russo GI, Scandura C, Di Mauro M, et al: Clinical efficacy of serenoa repens versus placebo versus alpha-blockers for the treatment of lower urinary tract symptoms/benign prostatic enlargement: a systematic review and network meta-analysis of randomized placebo-controlled clinical trials. Eur Urol Focus 7(2):420-431, 2021. doi:10.1016/j.euf.2020.01.002

  6. 6. Trivisonno LF, Sgarbossa N, Alvez GA, et alSerenoa repens for the treatment of lower urinary tract symptoms due to benign prostatic enlargement: a systematic review and meta-analysis. Investig Clin Urol 62(5):520-534, 2021. doi:10.4111/icu.20210254

  7. 7. Elterman D, Aubé-Peterkin M, Evans H, et al: UPDATE - Canadian Urological Association guideline: male lower urinary tract symptoms/benign prostatic hyperplasia. Can Urol Assoc J 16(8):245-256, 2022. doi:10.5489/cuaj.7906

  8. 8. Anceschi R, Bisi M, Ghidini N, et al: Serenoa repens (Permixon®) reduces intra- and postoperative complications of surgical treatments of benign prostatic hyperplasia. Minerva Urol Nefrol 62(3):219-223, 2010.

  9. 9. Lapi F, Gallo E, Giocaliere E, et al: Acute liver damage due to Serenoa repens: a case report. Br J Clin Pharmacol 69(5):558-560, 2010. doi:  10.1111/j.1365-2125.2010.03618.x

  10. 10. Wargo KA, Allman E, Ibrahim FSouth Med J 103(7):683-685, 2010. doi: 10.1097/SMJ.0b013e3181e1e3ee

  11. 11. Habib FK, Wyllie MG: Not all brands are created equal: a comparison of selected components of different brands of Serenoa repens extract. Prostate Cancer Prostatic Dis 7(3):195-200, 2004. doi:10.1038/sj.pcan.4500746

  12. 12. Izzo AA, Ernst E: Interactions between herbal medicines and prescribed drugs: an updated systematic review. Drugs 69(13):1777-1798, 2009. doi: 10.2165/11317010-000000000-00000

More Information

The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

  1. National Institutes of Health (NIH), National Center for Complementary and Integrative Health:

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