Saw Palmetto

The indigenous peoples of the southeastern United States used saw palmetto berries both as food and as medicine, long before European contact ^{27Reference 27Booker et al. · 2014A phytochemical comparison of saw palmetto products using gas chromatography and 1H NMR metabolomic profilingView study →}.

In Western herbal practice the berry has long been associated with the prostate gland ^{29Reference 29Bone et al. · 2013Principles and Practice of Phytotherapy (2nd ed.)}. Other traditional uses include respiratory complaints, especially chronic catarrh and bronchitis, genitourinary infection and inflammation, inflammation of the breast or testes, and use as an aphrodisiac for both men and women ^{27,29Reference 27Booker et al. · 2014A phytochemical comparison of saw palmetto products using gas chromatography and 1H NMR metabolomic profilingView study →Reference 29Bone et al. · 2013Principles and Practice of Phytotherapy (2nd ed.)}.

The British Herbal Pharmacopoeia lists saw palmetto as a diuretic, urinary antiseptic, endocrine agent and anabolic agent. It gives it for chronic or subacute cystitis, prostatic hypertrophy, genito-urinary catarrh, testicular atrophy and sex-hormone disorders ^{30Reference 30British Herbal Medicine Association · 1983British Herbal Pharmacopoeia}.

The Eclectic physicians called saw palmetto “the old man’s friend” and used it for chronic respiratory conditions and for problems of the prostate and libido ^{29Reference 29Bone et al. · 2013Principles and Practice of Phytotherapy (2nd ed.)}.

BPH is a non-cancerous enlargement of the prostate that obstructs urine flow and causes lower urinary tract symptoms (LUTS).

The STEP trial randomised 225 men over 49 to 160 mg of extract twice daily or placebo for one year, and found no difference in symptom scores, urine flow, prostate size or PSA ^{1Reference 1Bent et al. · 2006RCTSaw palmetto for benign prostatic hyperplasia — randomized controlled trial (RCT)View study →}. The larger CAMUS trial raised the dose in steps to three times the standard (960 mg/day) in 369 men over 72 weeks, and still found no benefit over placebo on any outcome ^{2Reference 2Barry et al. · 2011RCTEffect of increasing doses of saw palmetto extract on lower urinary tract symptoms — a randomized trial (RCT)View study →}.

The 2023 Cochrane review pooled 27 studies in 4,656 men and superseded the 2012 version ^{3,4Reference 3Franco et al. · 2023Meta-analysisSerenoa repens for the treatment of lower urinary tract symptoms due to benign prostatic enlargement — systematic review and meta-analysisView study →Reference 4Tacklind et al. · 2012Meta-analysisSerenoa repens for benign prostatic hyperplasia — systematic review and meta-analysis (superseded by the 2023 update)View study →}. It concluded that Serenoa repens alone gives little to no benefit for urinary symptoms or quality of life, rating both findings as high-certainty evidence ^{3Reference 3Franco et al. · 2023Meta-analysisSerenoa repens for the treatment of lower urinary tract symptoms due to benign prostatic enlargement — systematic review and meta-analysisView study →}.

Meta-analyses restricted to the hexane extract (Permixon) report different results. Compared with placebo it reduced night-time voids and increased maximum urine flow, and it performed similarly to tamsulosin ^{5,6Reference 5Novara et al. · 2016Meta-analysisEfficacy and safety of hexanic lipidosterolic extract of Serenoa repens (Permixon) in LUTS due to BPH — systematic review and meta-analysis of randomized controlled trialsView study →Reference 6Vela-Navarrete et al. · 2018Meta-analysisEfficacy and safety of a hexanic extract of Serenoa repens (Permixon) for LUTS/BPH — systematic review and meta-analysis of randomised controlled trials and observational studiesView study →}. A separate meta-analysis of four trials in 1,080 men found saw palmetto and tamsulosin equivalent for symptom scores and quality of life after at least six months ^{8Reference 8Cai et al. · 2020Meta-analysisComparison of Serenoa repens with tamsulosin in the treatment of benign prostatic hyperplasia — systematic review and meta-analysisView study →}. A drug review of the hexane extract summarises this case ^{9Reference 9Blair · 2022ReviewHexanic extract of Serenoa repens (Permixon): a review in symptomatic benign prostatic hyperplasia — reviewView study →}.

A network meta-analysis of 22 trials in 8,564 men found no clinically meaningful improvement in symptoms or urine flow from saw palmetto, whether hexane or non-hexane extracts ^{7Reference 7Russo et al. · 2021Meta-analysisClinical efficacy of Serenoa repens versus placebo versus alpha-blockers for LUTS/BPE — systematic review and network meta-analysis of randomized placebo-controlled trialsView study →}.

Adding the hexane extract to alfuzosin gave greater symptom relief than alfuzosin alone over 12 months in 300 men ^{10Reference 10Bevilacqua et al. · 2026RCTEfficacy of Serenoa repens extract combined with alfuzosin versus alfuzosin alone in men with LUTS due to BPH — multicenter randomized study (RCT)View study →}. In 68 healthy Japanese adults over 50 with frequent urination, a saw palmetto fruit extract reduced daytime urinary frequency and its bother over 12 weeks, in an industry-sponsored trial ^{11Reference 11Kimura et al. · 2025RCTBeneficial effects of saw palmetto (Serenoa repens) fruit extract on urinary symptoms of healthy Japanese adults — randomized, double-blind, placebo-controlled study (RCT)View study →}.

An uncontrolled 1998 study in 50 men found symptom scores improved over six months while urine flow, residual volume and bladder pressure did not change ^{28Reference 28Gerber et al. · 1998Clinical trialSaw palmetto (Serenoa repens) in men with lower urinary tract symptoms — clinical trial of urodynamic and voiding effectsView study →}.

Gap: the two largest dose-escalated trials and the latest Cochrane review are null ^{1,2,3Reference 1Bent et al. · 2006RCTSaw palmetto for benign prostatic hyperplasia — randomized controlled trial (RCT)View study →Reference 2Barry et al. · 2011RCTEffect of increasing doses of saw palmetto extract on lower urinary tract symptoms — a randomized trial (RCT)View study →Reference 3Franco et al. · 2023Meta-analysisSerenoa repens for the treatment of lower urinary tract symptoms due to benign prostatic enlargement — systematic review and meta-analysisView study →}. The positive data are specific to the Permixon extract and partly industry-associated, so they cannot be generalised to teas, whole-berry powders or unstandardised capsules.

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a pain condition of the pelvis in men, linked to inflammation.

A multicentre, double-blind, placebo-controlled phase 4 trial randomised men 2:1 to a Serenoa repens extract or placebo for 12 weeks, with 221 men analysed (148 and 73) ^{12Reference 12Zhang et al. · 2021RCTEfficacy and safety of Serenoa repens extract for chronic prostatitis/chronic pelvic pain syndrome — multicenter, randomized, double-blind, placebo-controlled trial (RCT)View study →}. The extract significantly improved the NIH Chronic Prostatitis Symptom Index total and sub-scores from two weeks onward, and more men responded to it than to placebo ^{12Reference 12Zhang et al. · 2021RCTEfficacy and safety of Serenoa repens extract for chronic prostatitis/chronic pelvic pain syndrome — multicenter, randomized, double-blind, placebo-controlled trial (RCT)View study →}.

A 2022 systematic review and meta-analysis also examined its use in CP/CPPS ^{13Reference 13Lok et al. · 2022Meta-analysisIs Serenoa repens effective for chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS)? — systematic review and meta-analysisView study →}. Anti-inflammatory activity, including lower TNF-α, IL-1β and IL-18 in cells, is the proposed mechanism ^{25Reference 25Zhang et al. · 2025In vitroSaw palmetto extract ameliorates benign prostatic hyperplasia by regulating 5α-reductase and apoptosis in vitro and in vivo (rat) — animal modelView study →}.

Gap: the evidence rests on one well-conducted monotherapy trial. It has not been independently replicated, and follow-up beyond 12 weeks is unstudied.

Male-pattern hair loss shares its main mechanism with BPH, the conversion of testosterone to dihydrotestosterone (DHT) by 5α-reductase.

The first placebo-controlled, double-blind trial tested a liposterolic saw palmetto extract combined with beta-sitosterol in men with mild to moderate hair loss. Six of the 10 men on the active formulation were rated improved at the final visit ^{15Reference 15Prager et al. · 2002RCTA randomized, double-blind, placebo-controlled trial of botanically derived inhibitors of 5α-reductase in androgenetic alopecia (RCT)View study →}.

In a two-year open-label study of 100 men, 38% of those taking saw palmetto 320 mg/day had increased hair growth, against 68% of those taking finasteride 1 mg ^{16Reference 16Rossi et al. · 2012RCTComparative effectiveness of finasteride vs Serenoa repens in male androgenetic alopecia: a two-year study — randomized comparative study (RCT)View study →}. Saw palmetto acted mainly on the crown ^{16Reference 16Rossi et al. · 2012RCTComparative effectiveness of finasteride vs Serenoa repens in male androgenetic alopecia: a two-year study — randomized comparative study (RCT)View study →}. An open, uncontrolled 24-week study of topical saw palmetto products in 50 men found hair counts increased ^{17Reference 17Wessagowit et al. · 2016Treatment of male androgenetic alopecia with topical products containing Serenoa repens extract — comparative studyView study →}.

A 2025 network meta-analysis of 19 trials of supplements for hair loss found that saw palmetto extract scored higher than placebo or conventional treatment on blinded doctor assessment ^{18Reference 18Zhou et al. · 2025Meta-analysisEffects of dietary supplements on androgenetic alopecia — systematic review and network meta-analysisView study →}. In human hair follicles kept alive in culture, a proprietary extract prolonged the growth phase independently of 5α-reductase ^{19Reference 19Broadley et al. · 2026In vitroA proprietary lipidosterolic extract of Serenoa repens promotes hair growth through mechanisms extending beyond 5α-reductase inhibition — in vitro human hair-follicle organ cultureView study →}.

Gap: only one small placebo-controlled trial exists, the larger comparison was open-label, and finasteride outperformed saw palmetto head to head ^{15,16Reference 15Prager et al. · 2002RCTA randomized, double-blind, placebo-controlled trial of botanically derived inhibitors of 5α-reductase in androgenetic alopecia (RCT)View study →Reference 16Rossi et al. · 2012RCTComparative effectiveness of finasteride vs Serenoa repens in male androgenetic alopecia: a two-year study — randomized comparative study (RCT)View study →}. There are no long-term or standardised-dose efficacy data.

This work concerns how the extract might act on the prostate rather than a separate clinical use.

In human prostate cancer cell lines, the hexane extract inhibited 5α-reductase without reducing PSA expression ^{21Reference 21Habib et al. · 2005In vitroSerenoa repens (Permixon) inhibits the 5α-reductase activity of human prostate cancer cell lines without interfering with PSA expression — in vitroView study →}. In a randomised open pilot study, men with BPH who took the extract (160 mg twice daily) for three months before prostate surgery showed a higher Bax-to-Bcl-2 ratio and signs of increased caspase-3 activity in the removed tissue, both markers of cell death ^{22Reference 22Vela-Navarrete et al. · 2005RCTSerenoa repens treatment modifies bax/bcl-2 index expression and caspase-3 activity in prostatic tissue — randomised open pilot studyView study →}.

In TRAMP mice, a diet delivering 300 mg/kg/day of extract lowered prostatic DHT, increased apoptosis and reduced tumour grade and incidence ^{24Reference 24Wadsworth et al. · 2007AnimalEffects of dietary saw palmetto on the prostate of the transgenic adenocarcinoma of the mouse prostate (TRAMP) model — animal model / in vivoView study →}. In rats with testosterone-induced prostate enlargement and in LNCaP cells, the extract reduced prostate weight, androgen receptor, PSA and 5α-reductase type 2, and lowered TNF-α, IL-1β and IL-18 ^{25Reference 25Zhang et al. · 2025In vitroSaw palmetto extract ameliorates benign prostatic hyperplasia by regulating 5α-reductase and apoptosis in vitro and in vivo (rat) — animal modelView study →}.

The picture is not uniform. One cell-line study found no apoptotic effect at either concentration tested, and found the extract a weak inhibitor of 5α-reductase compared with finasteride ^{23Reference 23Hill et al. · 2004In vitroEffect of Permixon on human prostate cell growth: lack of apoptotic action — in vitroView study →}. The early androgen-binding data come from foreskin fibroblasts rather than prostate ^{20Reference 20Sultan et al. · 1984In vitroInhibition of androgen metabolism and binding by a liposterolic extract of Serenoa repens in human foreskin fibroblasts — in vitroView study →}.

All of this is in vitro, tissue or animal work. No trial has measured an inflammatory clinical endpoint.

Tolerability. In the large randomised trials, side-effect rates were similar to placebo, and no serious harm was attributed to the extract ^{1,2,3Reference 1Bent et al. · 2006RCTSaw palmetto for benign prostatic hyperplasia — randomized controlled trial (RCT)View study →Reference 2Barry et al. · 2011RCTEffect of increasing doses of saw palmetto extract on lower urinary tract symptoms — a randomized trial (RCT)View study →Reference 3Franco et al. · 2023Meta-analysisSerenoa repens for the treatment of lower urinary tract symptoms due to benign prostatic enlargement — systematic review and meta-analysisView study →}. Stomach upset is the most frequent complaint ^{6Reference 6Vela-Navarrete et al. · 2018Meta-analysisEfficacy and safety of a hexanic extract of Serenoa repens (Permixon) for LUTS/BPH — systematic review and meta-analysis of randomised controlled trials and observational studiesView study →}.

PSA and prostate cancer. Unlike finasteride, saw palmetto did not change serum PSA in the large placebo-controlled trials ^{1Reference 1Bent et al. · 2006RCTSaw palmetto for benign prostatic hyperplasia — randomized controlled trial (RCT)View study →}, so it does not mask PSA screening. Prostate cancer should still be ruled out before long-term use, so that symptom relief does not delay a diagnosis.

Anti-androgens. Because the extract has anti-androgen activity, it may add to the effect of finasteride, dutasteride or other anti-androgens. No clinically significant interaction has been shown.

Bleeding and the liver. A case report describes blood in the urine with prolonged clotting times in a man taking saw palmetto ^{31Reference 31Villanueva et al. · 2009Case reportCoagulopathy induced by saw palmetto: a case report — case reportView study →}, and another describes a postoperative bleed into the abdomen in a man who had taken it before surgery ^{36Reference 36Venkateswaran et al. · 2020Case reportPostoperative retroperitoneal hematoma: a case of saw palmetto and the importance of primary care intervention — case reportView study →}. A further report describes hepatitis and pancreatitis that cleared when saw palmetto was stopped and returned twice when it was restarted ^{32Reference 32Jibrin et al. · 2006Case reportSaw palmetto-induced pancreatitis — case reportView study →}. Care is reasonable with anticoagulants or antiplatelet drugs and in liver disease.

Product quality. A study of 57 products found wide variation in fatty-acid content, some products with added olive or soybean oil, and one suspected of adulteration with another plant oil ^{27Reference 27Booker et al. · 2014A phytochemical comparison of saw palmetto products using gas chromatography and 1H NMR metabolomic profilingView study →}. A standardised extract is the reliable choice.

“Post-Serenoa syndrome.” A 2026 Italian case series proposed a post-Serenoa syndrome: persistent sexual and psychiatric symptoms after stopping the herb, by analogy with post-finasteride syndrome ^{26Reference 26Firenzuoli et al. · 2026Case reportCan we identify a post-Serenoa syndrome (PSS)? A case series on sexual and psychiatric side effects of Serenoa repensView study →}. The cases came from self-reports to an online forum, causality was rated “probable” in 54%, and combined use with finasteride was linked to more severe and lasting symptoms ^{26Reference 26Firenzuoli et al. · 2026Case reportCan we identify a post-Serenoa syndrome (PSS)? A case series on sexual and psychiatric side effects of Serenoa repensView study →}. A meta-analysis of clinical trials found no significant effect on male sexual function compared with placebo or tamsulosin ^{14Reference 14Paulis et al. · 2021Meta-analysisSerenoa repens and its effects on male sexual function — systematic review and meta-analysis of clinical trialsView study →}.

Drug metabolism. In healthy volunteers, 28 days of saw palmetto extract did not change the activity of the drug-metabolising enzymes CYP1A2, CYP2D6, CYP2E1 or CYP3A4 ^{39Reference 39Gurley et al. · 2004AnimalIn vivo assessment of botanical supplementation on human cytochrome P450 phenotypes: Citrus aurantium, Echinacea purpurea, milk thistle, and saw palmettoView study →}. In a second volunteer study, 320 mg a day for 14 days left alprazolam (a CYP3A4 marker) and dextromethorphan (a CYP2D6 marker) unchanged ^{40Reference 40Markowitz et al. · 2003Multiple doses of saw palmetto (Serenoa repens) did not alter cytochrome P450 2D6 and 3A4 activity in normal volunteersView study →}. Interactions through these enzymes look unlikely at usual doses.