Saw palmetto
A 2023 Cochrane review of 27 trials found little to no difference from placebo in urinary symptoms or quality of life, at high certainty. Two large NIH-funded trials agree. Pooled trials found no change in sexual function. Hair loss evidence is small, with one 60-person placebo trial of a branded extract. Adverse events matched placebo.
Add to Bio HackChecked 2026-11-09
- Status
- Dietary supplement in the US. Not approved by the FDA as a drug for any use.
- Also called
- Serenoa repens, Sabal serrulata, saw palmetto berry, saw palmetto extract, Permixon, hexanic extract of Serenoa repens, HESr
- Taken for
- prostate health, enlarged prostate, urinary symptoms, nighttime urination, hair loss, DHT, testosterone, libido
Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on
Shown to help1
Reported risks1
What people take it for, and what was found
Shown to help1
Hair loss
Limited evidence: small trials found more hair growth or density, often with combination products, and less growth than finasteride in one unblinded study.
The numbers and sources
- Effect
- A systematic review of 5 RCTs and 2 prospective cohorts of topical and oral products containing saw palmetto reported 60% improvement in overall hair quality, 27% improvement in total hair count and increased density in 83.3% of patients [5]. In an open-label 2-year study of 100 men, 38% on 320 mg saw palmetto a day had more hair growth, against 68% on 1 mg finasteride [6]. In a 6-month placebo-controlled trial of one oral extract, total terminal hair count changed by +18.6 against -10.1 on placebo, and total hair density by +25.1 against -12.2 (both p < 0.001) [7].
- Population
- Adults with androgenetic alopecia or telogen effluvium [5]. 100 men with mild to moderate androgenetic alopecia [6]. 60 men and women with self-perceived thinning hair, 40 on the extract and 20 on placebo [7].
- Sources
- [5], [6], [7]
- Caveats
- Many products combined saw palmetto with other ingredients [5]. The finasteride comparison had no placebo and no blinding [6]. The placebo trial tested one branded extract (SEREVELLE, Valensa International), had a single author and enrolled people by self-perceived thinning rather than diagnosis [7].
Not shown to help3
Urinary symptoms from an enlarged prostate
Not shown to improve urinary symptoms or quality of life in men with an enlarged prostate, even at three times the standard dose.
The numbers and sources
- Effect
- In 27 trials (4,656 men), limited to low risk of bias studies, saw palmetto made little to no difference in symptom scores at 3 to 6 months (IPSS MD -0.90 on a 0 to 35 scale, 95% CI -1.74 to -0.07, 9 studies, 1,681 men) or at 12 to 17 months (MD 0.07, 95% CI -0.75 to 0.88), and little to no difference in quality of life, all at high certainty [1]. In 225 men given 160 mg twice a day for a year, symptom scores (MD 0.04, 95% CI -0.93 to 1.01) and urine flow did not differ from placebo [2]. In 369 men given up to 3 times the standard dose over 72 weeks, symptom scores fell 2.20 points on saw palmetto and 2.99 on placebo [3].
- Population
- Men mostly over 50 with moderate symptoms [1][2][3].
- Sources
- [1], [2], [3]
- Caveats
- Ten of the 27 Cochrane trials were industry funded [1]. A meta-analysis limited to one hexanic extract, Permixon, and funded by its maker's Spanish arm, Pierre Fabre Ibérica, reported 0.64 fewer voids a night and 2.75 mL/s more peak flow than placebo [4].
Sexual function and libido
Not shown to improve sexual function or quality of life in men with an enlarged prostate, in very low certainty evidence.
The numbers and sources
- Effect
- Across 6 RCTs, sexual function did not differ from placebo (Hedges' g -0.08, 95% CI -0.93 to 0.77, I² 96%). In the trials that used the IIEF questionnaire, the result was g -0.21 (95% CI -0.54 to 0.13, I² 29%). Quality of life did not improve either [8].
- Population
- Men with benign prostatic hyperplasia in 6 RCTs [8].
- Sources
- [8]
- Caveats
- Certainty was very low. The pooled analysis combined different sexual function questionnaires, and the prediction interval ran from -2.45 to 2.29 [8].
Testosterone
Limited evidence: blood testosterone did not change after 30 days in 20 men with an enlarged prostate. Prostate tissue studies found less DHT on saw palmetto.
Compared with before treatment, in the same men [10]; untreated men having the same surgery [11]; placebo [12]
The numbers and sources
- Effect
- In 20 men aged 50 to 75 with an enlarged prostate, 160 mg twice a day for 30 days did not change plasma testosterone, FSH or LH [10]. In prostate tissue from men given 320 mg a day for 3 months, DHT was lower and testosterone higher than in untreated men, mainly in the periurethral region [11]. In a 6-month randomized trial of a saw palmetto herbal blend, prostate tissue DHT fell modestly but significantly against placebo [12].
- Population
- 20 men with benign prostatic hyperplasia, mean age 67 [10]. Men having prostate surgery, treated or untreated [11]. 40 men with benign prostatic hyperplasia [12].
- Sources
- [10], [11], [12]
- Caveats
- The blood hormone study was small, short and had no control group [10]. The tissue studies measured hormones inside the prostate, not in the blood, and one tested a herbal blend [12]. No study in men without prostate disease was located.
Doses studied
Most prostate trials used 320 mg a day [3][4]. The 1-year trial gave 160 mg twice a day [2], and the 72-week trial raised the dose to 640 and then 960 mg a day [3]. Hair trials used 100 to 320 mg [5].
Risks
Reported risks1
Reported side effects and serious case reports
Case reports: death and brain bleeding appeared in isolated reports with questionable causality. Stomach upset, headache and lower libido were the most often reported effects.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- A systematic review of 40 articles, plus WHO and national reporting schemes, found the most frequent adverse events were abdominal pain, diarrhea, nausea, fatigue, headache, decreased libido and rhinitis. Death and cerebral hemorrhage appeared in isolated case reports and spontaneous reports, with causality questionable. No drug interactions were reported [9]. In the Permixon review, gastrointestinal disorders were the most frequent reaction, at 3.8% [4].
- Population
- 26 RCTs, other trials and case reports [9].
- Sources
- [9], [4]
- Caveats
- Spontaneous reports cannot give a rate. The authors note adverse event reporting was poor [9].
Checked, no increase found1
Adverse events in trials
Adverse events were about as common as on placebo across 12 trials in 2,399 men. Data beyond 17 months is lacking.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- Across 12 trials (2,399 men), adverse events did not differ from placebo (RR 1.01, 95% CI 0.77 to 1.31), about 2 more per 1,000 men than the 164 per 1,000 on placebo, at moderate certainty [1]. Side effects were similar to placebo in the 1-year trial [2], and no clearly attributable adverse effects were found at triple dose [3].
- Population
- Men in RCTs [1][2][3].
- Sources
- [1], [2], [3]
- Caveats
- No data on adverse events beyond 17 months [1].
Claims tested and not found
- That saw palmetto eases prostate urinary symptoms. High-certainty evidence from 27 trials found little to no difference from placebo [1], and two NIH-funded trials found none at standard or triple dose [2][3].
- That saw palmetto shrinks the prostate or lowers PSA. Prostate size and PSA did not differ from placebo over one year [2].
- That saw palmetto improves sexual function in men with urinary symptoms. In the 72-week trial, no secondary outcome, including sexual function, differed in favor of saw palmetto against placebo [3]. Pooled across 6 RCTs, sexual function did not differ from placebo [8].
Sources
- Franco JV, Trivisonno L, Sgarbossa NJ, et al. Serenoa repens for the treatment of lower urinary tract symptoms due to benign prostatic enlargement. Cochrane Database of Systematic Reviews. 2023. https://doi.org/10.1002/14651858.CD001423.pub4
- Bent S, Kane C, Shinohara K, et al. Saw Palmetto for Benign Prostatic Hyperplasia. New England Journal of Medicine. 2006. https://doi.org/10.1056/NEJMoa053085
- Barry MJ, Meleth S, Lee JY, et al. Effect of Increasing Doses of Saw Palmetto Extract on Lower Urinary Tract Symptoms: A Randomized Trial. JAMA. 2011. https://doi.org/10.1001/jama.2011.1364
- Vela-Navarrete R, Alcaraz A, Rodríguez-Antolín 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 International. 2018. https://doi.org/10.1111/bju.14362
- Evron E, Juhasz M, Babadjouni A, et al. Natural Hair Supplement: Friend or Foe? Saw Palmetto, a Systematic Review in Alopecia. Skin Appendage Disorders. 2020. https://doi.org/10.1159/000509905
- Rossi A, Mari E, Scarnò M, et al. Comparitive Effectiveness of Finasteride Vs Serenoa Repens in Male Androgenetic Alopecia: A Two-Year Study. International Journal of Immunopathology and Pharmacology. 2012. https://doi.org/10.1177/039463201202500435
- Ablon G. The Safety and Efficacy of a Novel Saw Palmetto (Serenoa repens) Extract for Promoting Hair Growth in Adults With Self-Perceived Thinning Hair: 180-Day Results. Journal of Cosmetic Dermatology. 2026. https://doi.org/10.1111/jocd.70717
- Dong C, Zheng J, Jiang Y. Effects of Serenoa repens extract on sexual function in patients with benign prostatic hyperplasia: a systematic review and meta-analysis. Sexual Medicine. 2026. https://doi.org/10.1093/sexmed/qfag088
- Agbabiaka TB, Pittler MH, Wider B, et al. Serenoa repens (Saw Palmetto): A Systematic Review of Adverse Events. Drug Safety. 2009. https://doi.org/10.2165/00002018-200932080-00003
- Casarosa C, Cosci di Coscio M, Fratta M. Lack of effects of a lyposterolic extract of Serenoa repens on plasma levels of testosterone, follicle-stimulating hormone, and luteinizing hormone. Clinical Therapeutics. 1988. https://pubmed.ncbi.nlm.nih.gov/2485240/
- Di Silverio F, Monti S, Sciarra A, et al. Effects of long-term treatment with Serenoa repens (Permixon) on the concentrations and regional distribution of androgens and epidermal growth factor in benign prostatic hyperplasia. The Prostate. 1998. https://doi.org/10.1002/(sici)1097-0045(19981001)37:2<77::aid-pros3>3.0.co;2-i
- Marks LS, Hess DL, Dorey FJ, et al. Tissue effects of saw palmetto and finasteride: use of biopsy cores for in situ quantification of prostatic androgens. Urology. 2001. https://doi.org/10.1016/s0090-4295(00)01052-9