Saw Palmetto

Many men report use of saw palmetto to treat symptoms (eg, frequent urination) of benign prostatic hyperplasia (BPH). Additional claims are that saw palmetto increases sperm production, breast size, and sexual vigor. Saw palmetto has also been used to stimulate hair growth.Many men report use of saw palmetto to treat symptoms (eg, frequent urination) of benign prostatic hyperplasia (BPH). Additional claims are that saw palmetto increases sperm production, breast size, and sexual vigor. Saw palmetto has also been used to stimulate hair growth.

There is no scientific evidence to suggest that saw palmetto reverses BPH as measured by imaging techniques (eg, ultrasound or MRI). Study results are mixed when evaluating urologic symptoms of BPH. A double-blind, multicenter, placebo-controlled randomized trial of 369 men found that increasing doses of a saw palmetto fruit extract did not reduce lower urinary tract symptoms more than placebo (There is no scientific evidence to suggest that saw palmetto reverses BPH as measured by imaging techniques (eg, ultrasound or MRI). Study results are mixed when evaluating urologic symptoms of BPH. A double-blind, multicenter, placebo-controlled randomized trial of 369 men found that increasing doses of a saw palmetto fruit extract did not reduce lower urinary tract symptoms more than placebo (1). In addition, a Cochrane review of 32 randomized trials determined that saw palmetto, at double and triple doses, did not improve urinary flow measures or prostate size in men with lower urinary tract symptoms consistent with BPH (). In addition, a Cochrane review of 32 randomized trials determined that saw palmetto, at double and triple doses, did not improve urinary flow measures or prostate size in men with lower urinary tract symptoms consistent with BPH (2). However, another meta-analysis of 27 studies (5800 patients) of a specific hexanic extract of saw palmetto found decreased nocturia and improved urine flow (). However, another meta-analysis of 27 studies (5800 patients) of a specific hexanic extract of saw palmetto found decreased nocturia and improved urine flow (3), whereas a subsequent Cochrane review of 27 studies with 4656 patients comparing saw palmetto monotherapy or combination therapy with other phytotherapeutic agents to placebo concluded that there was little to no difference in urologic symptoms or International Prostate Symptom Scores (IPSSs) at short- or long-term follow-up (), whereas a subsequent Cochrane review of 27 studies with 4656 patients comparing saw palmetto monotherapy or combination therapy with other phytotherapeutic agents to placebo concluded that there was little to no difference in urologic symptoms or International Prostate Symptom Scores (IPSSs) at short- or long-term follow-up (4).

A 2020 meta-analysis of 4 studies in 1080 males reported that saw palmetto had comparable efficacy to tamsulosin in men with BPH. There were no statistically significant differences in IPSSs, maximum flow rate, postvoid residual volume, or quality of life (A 2020 meta-analysis of 4 studies in 1080 males reported that saw palmetto had comparable efficacy to tamsulosin in men with BPH. There were no statistically significant differences in IPSSs, maximum flow rate, postvoid residual volume, or quality of life (5). However, a 2021 network meta-analysis of 22 randomized controlled trials (8564 subjects) comparing saw palmetto to placebo and various alpha-blockers reported lack of meaningful improvement in lower urinary tract symptoms (LUTS) and peak urine flow (). However, a 2021 network meta-analysis of 22 randomized controlled trials (8564 subjects) comparing saw palmetto to placebo and various alpha-blockers reported lack of meaningful improvement in lower urinary tract symptoms (LUTS) and peak urine flow (6). A different 2021 meta-analysis of 27 trials (4853 subjects) reported lack of benefit for saw palmetto in treating LUTS attributable to BPH (). A different 2021 meta-analysis of 27 trials (4853 subjects) reported lack of benefit for saw palmetto in treating LUTS attributable to BPH (7). Thus, there are numerous studies evaluating saw palmetto for BPH or LUTS, with varying results. Canadian Urological Association Guidelines do not endorse phytotherapies (including saw palmetto) for BPH treatment (). Thus, there are numerous studies evaluating saw palmetto for BPH or LUTS, with varying results. Canadian Urological Association Guidelines do not endorse phytotherapies (including saw palmetto) for BPH treatment (8).

A small, randomized, controlled trial reported that saw palmetto used for 2 months prior to transurethral resection of the prostate resulted in shortened surgery duration and a more favorable postoperative course (A small, randomized, controlled trial reported that saw palmetto used for 2 months prior to transurethral resection of the prostate resulted in shortened surgery duration and a more favorable postoperative course (9).

A systematic review of 5 trials and 2 prospective cohort studies reported improvement in overall hair quality, total hair count, and hair density, although larger high-quality trials are needed to confirm this effect (10).

Claims that saw palmetto increases sperm production, breast size, or sexual vigor are unsupported.Claims that saw palmetto increases sperm production, breast size, or sexual vigor are unsupported.

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

One case report of a 58-year-old White man taking 900 mg of dried extract and 660 mg of berry powder to ease the symptoms of BPH reported acute liver damage due to saw palmetto (One case report of a 58-year-old White man taking 900 mg of dried extract and 660 mg of berry powder to ease the symptoms of BPH reported acute liver damage due to saw palmetto (11). Another report of a 65-year-old male indicated that supplementation with saw palmetto may have been responsible for acute pancreatitis (). Another report of a 65-year-old male indicated that supplementation with saw palmetto may have been responsible for acute pancreatitis (12).

Women who are pregnant or who may become pregnant should not take saw palmetto due to potential hormonal effects.Women who are pregnant or who may become pregnant should not take saw palmetto due to potential hormonal effects.

Variability in ingredients and concentrations in saw palmetto supplements may affect safety and efficacy (Variability in ingredients and concentrations in saw palmetto supplements may affect safety and efficacy (13).

No interactions have been reported for saw palmetto (No interactions have been reported for saw palmetto (14); however, although strong evidence is not available, patients on warfarin should be careful when considering or taking saw palmetto because of a possible risk of hepatotoxicity or bleeding. ); however, although strong evidence is not available, patients on warfarin should be careful when considering or taking saw palmetto because of a possible risk of hepatotoxicity or bleeding.

Saw palmetto may interact with Saw palmetto may interact withestrogens in oral contraceptives or hormone replacement therapy and decrease their benefit.

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

1. 1. Barry MJ, Meleth S, Lee JY, et al; Complementary and Alternative Medicine for Urological Symptoms (CAMUS) Study Group. Effect of increasing doses of saw palmetto extract on lower urinary tract symptoms: a randomized trial. . Effect of increasing doses of saw palmetto extract on lower urinary tract symptoms: a randomized trial.JAMA. 306(12):1344-1351, 2011. doi: 10.1001/jama.2011.1364

2. 2. Wilt T, Ishani A, Macdonald R, et al: Serenoa repens for benign prostatic hyperplasia. Cochrane Database Syst Rev 2002;93012: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. Franco JV, Trivisonno L, Sgarbossa NJ, Alvez GA, Fieiras C, Escobar Liquitay CM, Jung JH. Serenoa repens for the treatment of lower urinary tract symptoms due to benign prostatic enlargement. Cochrane Database Syst Rev. 2023 Jun 22;6(6):CD001423. doi: 10.1002/14651858.CD001423.pub4

5. 5. Cai T, Cui Y, Yu S, et al. Comparison of serenoa repens with tamsulosin in the treatment of B=benign prostatic hyperplasia: a systematic review and meta-analysis. with tamsulosin in the treatment of B=benign prostatic hyperplasia: a systematic review and meta-analysis.Am J Mens Health. 14(2):1557988320905407, 2020. doi:10.1177/1557988320905407

6. 6. 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

7. 7. Trivisonno LF, Sgarbossa N, Alvez GA, et al. Serenoa 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

8. 8. 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

9. 9. 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.

10. 10. Evron E, Juhasz M, Babadjouni A, Mesinkovska NA. Natural Hair Supplement: Friend or Foe? Saw Palmetto, a Systematic Review in Alopecia. . Natural Hair Supplement: Friend or Foe? Saw Palmetto, a Systematic Review in Alopecia.Skin Appendage Disord. 2020;6(6):329-337. doi:10.1159/000509905

11. 11. 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

12. 12. Wargo KA, Allman E, Ibrahim F.A possible case of saw palmetto-induced pancreatitis. .A possible case of saw palmetto-induced pancreatitis.South Med J. 103(7):683-685, 2010. doi: 10.1097/SMJ.0b013e3181e1e3ee

13. 13. 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

14. 14. 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

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: Saw Palmetto