Saw Palmetto

Purported Benefits, Side Effects & More

Saw Palmetto

Purported Benefits, Side Effects & More
Saw Palmetto

Common Names

  • American dwarf palm tree
  • Cabbage palm

For Patients & Caregivers

Tell your healthcare providers about any dietary supplements you’re taking, such as herbs, vitamins, minerals, and natural or home remedies. This will help them manage your care and keep you safe.

What is it?

Saw palmetto was shown in some studies to help relieve the symptoms of benign prostatic hypertrophy (BPH), but it has not been shown to prevent or treat prostate cancer.

Studies in the laboratory show that saw palmetto works by countering effects of male sex hormones such as testosterone and DHT. It appears to reduce levels of these hormones in body tissues like the prostate. Other studies have noted that saw palmetto reduces the conversion of testosterone to DHT, its more potent form. Saw palmetto berry extracts also reduce inflammation and swelling by preventing the formation of compounds that cause these reactions.

In a laboratory study, a saw palmetto extract was found to slow the growth of normal prostate cells and increase their sensitivity to radiation, while not affecting prostate cancer cells. Since this may increase the risk of complications, patients should consult with a physician before using saw palmetto supplements during radiation therapy.

What are the potential uses and benefits?
  • To treat benign prostatic hypertrophy (BPH)
    Several clinical trials and meta-analyses have shown that saw palmetto improves urinary tract symptoms associated with BPH.
  • To treat prostate cancer
    Saw palmetto shows anti-inflammatory and anti-androgen properties in laboratory studies and reduces the levels of DHT in the prostate in clinical trials. However, it is not an effective treatment for prostate cancer.
  • To promote urination
    A few studies have shown benefits of saw palmetto.
  • As an anti-inflammatory
    Various studies suggest anti-inflammatory effects.
What are the side effects?

Common: Gastrointestinal upset, diarrhea, fatigue, headache, decreased libido and rhinitis
Most effects are reported as mild and similar to effects with placebo.

Case reports

  • Potentially fatal blood accumulation around the heart: In a 76-year-old man taking a blood thinner for irregular heart rhythm who had also been taking saw palmetto. Although this condition appeared related to the use of his medication, saw palmetto may have contributed to this drug’s increased activity.
  • Severe bleeding during surgery
  • Blood in the urine and impaired blood clotting
  • Severe inflammation of the pancreas
  • Severe liver damage
  • Hot flashes and first menstrual cycle: Two cases in children who were treated with saw palmetto for hair disorders.
What else do I need to know?

Do Not Take if:

  • You are taking warfarin or other blood thinners: Saw palmetto may increase the risk of bruising and bleeding.
  • You are taking antiplatelets such as clopidogrel: Saw palmetto may increase the effects of these drugs.
  • You are taking nonsteroidal anti-inflammatory drugs (NSAIDs): Saw palmetto may increase the side effects of these drugs.

For Healthcare Professionals

Scientific Name
Serenoa repens
Clinical Summary

Saw palmetto is a dwarf palm that grows in the coastal lands of North America, West Indies, and Mediterranean countries. The fruits are a rich source of fatty acids and phytosterols and have been used to promote urination, reduce inflammation, and for treatment of conditions such as benign prostatic hyperplasia (BPH).

Various heterogeneous extracts of saw palmetto are available, but many basic research and clinical trials used a hexanic extract of S. repens, which has anti-inflammatory, anti-androgenic, and antiproliferative activities (36) (37). Whereas some data indicate that saw palmetto extracts improve lower urinary tract symptoms (LUTS) in both male   (2) (3) (4) (5) (15) (17) (18) (26) (50) (54) and female (55) patients with BPH, conflicting data suggest no such effects (6) (14) (19) (28) (38) (56). In another large study, a saw palmetto extract did not affect serum prostate specific antigen (PSA) more than placebo even at high doses (30). But pretreatment with saw palmetto reduced intra- and postoperative complications in patients who underwent transurethral resection of the prostate and open prostatectomy (22), and reduced prostatic inflammation (51). Data also suggest benefits against chronic prostatitis/chronic pelvic pain syndrome (57). A saw palmetto extract was found to inhibit growth of normal prostate cells and increase their sensitivity to radiation in vitro, but did not affect malignant prostate cancer cells (20). A large epidemiologic study did not find associations with the use of saw palmetto and reduced risk of prostate cancer (27).

In an exploratory study, a hexanic extract of S. repens demonstrated anti-inflammatory effects in patients with BPH-related LUTS (39). In an open-label study, saw palmetto extract plus tamsulosin was found to be more effective than tamsulosin alone in reducing storage symptoms in BPH patients (40); and a randomized trial reported benefits of saw palmetto and bifiprost for preventing chronic bacterial prostatitis due to enterobacteriaceae (52).

Multi-phytotherapy approaches have also been investigated. One study suggests saw palmetto may benefit patients with chronic bacterial prostatitis when co-administered with nettle, curcumin, and quercitin (16). In addition, saw palmetto exerted anti-inflammatory effects when combined with selenium and lycopene (31). In randomized trials, patients with LUTS had greater improvement in International Prostate Symptom Scores (IPSS) and increased urine flow with this combination therapy in addition to tamsulosin than with either single therapy (41). The combination was also reported comparable to tadalafil for improving IPSS and urine flow (53).

Due to the increased risk of normal tissue complications, patients should consult with a physician before using saw palmetto supplements during radiation therapy. Data on the effects of saw palmetto on symptom management during radiation therapy have yet to be published (32).

Purported Uses and Benefits
  • Benign prostatic hypertrophy (BPH)
  • Prostate cancer
  • Promote urination
  • Inflammation
Mechanism of Action

Studies with a liposterolic extract of saw palmetto berries showed that it reduced tissue uptake of both testosterone and dihydrotestosterone (DHT) by more than 40%, suggesting antiandrogenic activity (7). Further, the extract inhibited binding of DHT to its receptor (8) and blocked conversion of testosterone to DHT by inhibiting 5-alpha-reductase activity (9). The berries also inhibit cyclooxygenase and 5-lipoxygenase pathways, thereby preventing the biosynthesis of inflammation-producing prostaglandins and leukotrienes (10). Other possible mechanisms attributed to benefits in BPH include the blocking of estrogen receptor activity in the prostate as well as bladder muscle antispasmodic and anti-inflammatory activities (42). Possible mechanisms by which saw palmetto could cause hot flashes and vasomotor symptoms especially in children include its antiestrogenic activity influencing physiological endocrine activity and increased availability of sex hormone-binding globulin (35) (43).

Studies of a hexanic extract of S. repens suggests it decreases prostaglandin and leukotriene production to inhibit the arachidonic acid cascade and decreases B lymphocyte infiltrates and interleukin (IL)-1b and tumor necrosis factor (TNF)-a levels to adjust inflammatory status and gene expression (36). In animal models of prostate hyperplasia, it demonstrated a global anti-inflammatory effect on hyperplastic prostates with lobe-specific anti-androgenic effects (44). In human prostate and vascular cells in an inflammatory environment, it also decreases monocyte chemotactic protein-1 production and vascular cell adhesion molecule-1 expression (37). In human prostate carcinoma cells, inhibitory effects on cell growth were attributed to downregulation of inflammatory-related genes and activation of nuclear factor-kappa B pathway (45).

A chalcanonol glycoside from the seeds of saw palmetto as well as sterolic derivatives have demonstrated antiproliferative effects (46).

Adverse Reactions

Common: Gastrointestinal disturbances, diarrhea, fatigue, headache, decreased libido, rhinitis (47) (48)
Most effects are reported as mild and similar to effects with placebo (47).

Case reports

  • Hemopericardium: In a 76-year-old man receiving rivaroxaban who had also been taking saw palmetto. Although the development of hemopericardium appeared related to the use of rivaroxaban, saw palmetto may have contributed to the increase in rivaroxaban activity (49).
  • Intraoperative hemorrhage, anticoagulant effects and prolonged bleeding time: In a 53-year-old white male during surgical resection of a tumor, despite negative results for a workup for bleeding disorders and no preoperative use of anti-inflammatory medications. Further inquiry led to disclosed use of saw palmetto for BPH. Prolonged bleeding time normalized a few days after the patient stopped taking this supplement (11).
  • Hematuria and coagulopathy: In a 79-year-old man taking multiple medications along with long-term use of saw palmetto, the dosage of which he had recently increased to relieve BPH symptoms (21). Urinary symptoms and coagulation parameters improved with the discontinuation of saw palmetto.
  • Acute pancreatitis: In a 65-year-old man following use of saw palmetto for 1 week before onset of symptoms. His condition improved after treatment and avoiding saw palmetto (23).
  • Severe liver damage: In a 58-year-old man following consumption of saw palmetto to alleviate BPH symptoms (24).
  • Hot flashes and subsequent menarche: In an 11-year-old girl after treatment for a type of alopecia with a food supplement for 2 months that contained saw palmetto (35); and in a 10-year-old girl using a food supplement that contained saw palmetto extract to treat hirsutism. Symptoms abated when the supplement was discontinued and reappeared with a supplement “re-challenge”. Menarche also commenced about 4 months post-supplement (43).
  • Postoperative retroperitoneal hematoma: In a middle-aged man with a history of bilateral inguinal hernia repair after he took saw palmetto prior to surgery (58).
  • Fixed drug eruption with localized blisters and erosion: In a 61-year-old man who took saw palmetto for treating BPH. The eruption cleared after saw palmetto withdrawal (59).
Herb-Drug Interactions
  • Anticoagulants, antiplatelets: Saw palmetto may have additive anticoagulant effects, according to case reports (11) (21) (49).
  • Nonsteroidal anti-inflammatory drugs (NSAIDs): Saw palmetto may increase the risk of side effects with these drugs, according to a case report (21).
  • UGT (Uridine 5’-diphospho-glucuronosyltransferase) substrates: Saw palmetto inhibits UGT enzymes in vitro and can increase the side effects of drugs metabolized by them (25). Clinical relevance is not known.
  • CYP 450 substrates: Saw palmetto inhibits cytochrome P450 3A4, 2D6, and 2C9 and may interfere with the actions of drugs metabolized by these enzymes (29). Clinical relevance is not known.
Herb Lab Interactions
  • May prolong bleeding time (11)
Dosage (OneMSK Only)
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  10. Goldmann WH, Sharma AL, Currier SJ, et al. Saw palmetto berry extract inhibits cell growth and Cox-2 expression in prostatic cancer cells. Cell Biol Int 2001;25:1117-24.
  11. Cheema P, El-Mefty O, Jazieh AR, et al. Intraoperative haemorrhage associated with the use of extract of Saw Palmetto herb: a case report and review of literature. J Intern Med. 2001 Aug;250(2):167-9.
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  16. Cai T, Mazzoli S, Bechi A, et al. Serenoa repens associated with Urtica dioica (ProstaMEV) and curcumin and quercitin (FlogMEV) extracts are able to improve the efficacy of prulifloxacin in bacterial prostatitis patients: results from a prospective randomised study. Int J Antimicrob Agents. 2009 Jun;33(6):549-53.
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  20. Hasan Y, Schoenherr D, Martinez AA, et al. Prostate-specific natural health products (dietary supplements) radiosensitize normal prostate cells. Int J Radiat Oncol Biol Phys. 2010 Mar 1;76(3):896-904.
  21. Villanueva S, González J. Coagulopathy induced by saw palmetto: a case report. Bol Asoc Med P R. 2009 Jul-Sep;101(3):48-50.
  22. Anceschi R, Bisi M, Ghidini N, Ferrari G, Ferrari P. Serenoa repens (Permixon) reduces intra- and postoperative complications of surgical treatments of benign prostatic hyperplasia. Minerva Urol Nefrol. 2010 Sep;62(3):219-23.
  23. Wargo KA, Allman E, Ibrahim F. A possible case of saw palmetto-induced pancreatitis. South Med J. 2010 Jul;103(7):683-5.
  24. Lapi F, Gallo E, Giocaliere E, et al. Acute liver damage due to Serenoa repens: a case report. Br J Clin Pharmacol. 2010 May;69(5):558-60.
  25. Mohamed ME, Frye RF. Inhibitory Effects of Commonly Used Herbal Extracts on UGT1A4, 1A6, and 1A9 Enzyme Activities. Drug Metab Dispos. 2011 Jun 1. [Epub ahead of print]
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  27. Brasky TM, Kristal AR, Navarro SL, et al. Specialty supplements and prostate cancer risk in the VITamins and Lifestyle (VITAL) cohort. Nutr Cancer. 2011 May;63(4):573-82.
  28. 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;306(12):1344-1351.
  29. Yale SH, Glurich I. Analysis of the inhibitory potential of Ginkgo biloba, Echinacea purpurea, and Serenoa repens on the metabolic activity of cytochrome P450 3A4, 2D6, and 2C9 . J Altern Complement Med. 2005 Jun;11(3):433-9.
  30. Andriole GL, McCullum-Hill C, Sandhu GS, et al. The effect of increasing doses of saw palmetto fruit extract on serum prostate specific antigen: analysis of the CAMUS randomized trial. J Urol. 2013 Feb;189(2):486-92.
  31. Morgia G, Cimino S, Favilla V, et al. Effects of Serenoa repens, selenium and lycopene (Profluss®) on chronic inflammation associated with benign prostatic hyperplasia: results of “FLOG” (Flogosis and Profluss in Prostatic and Genital Disease), a multicentre Italian study. Int Braz J Urol. 2013 Mar-Apr;39(2):214-21.
  32. Saw Palmetto: Symptom Management for Men During Radiation Therapy. Accessed May 6, 2020.
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  35. Miroddi M, Carnì A, Mannucci C, et al. Hot flashes in a young girl: a wake-up call concerning Serenoa repens use in children. Pediatrics. 2012 Nov;130(5):e1374-6.
  36. Ficarra V, Rossanese M, Zazzara M, et al. The role of inflammation in lower urinary tract symptoms (LUTS) due to benign prostatic hyperplasia (BPH) and its potential impact on medical therapy. Curr Urol Rep. Dec 2014;15(12):463.
  37. Latil A, Libon C, Templier M, et al. Hexanic lipidosterolic extract of Serenoa repens inhibits the expression of two key inflammatory mediators, MCP-1/CCL2 and VCAM-1, in vitro. BJU Int. Sep 2012;110(6 Pt B):E301-307.
  38. MacDonald R, Tacklind JW, Rutks I, et al. Serenoa repens monotherapy for benign prostatic hyperplasia (BPH): an updated Cochrane systematic review. BJU Int. Jun 2012;109(12):1756-1761.
  39. Latil A, Petrissans MT, Rouquet J, et al. Effects of hexanic extract of Serenoa repens (permixon((R)) 160 mg) on inflammation biomarkers in the treatment of lower urinary tract symptoms related to benign prostatic hyperplasia. Prostate. Dec 2015;75(16):1857-1867.
  40. Ryu YW, Lim SW, Kim JH, et al. Comparison of tamsulosin plus Serenoa repens with tamsulosin in the treatment of benign prostatic hyperplasia in Korean men: 1-year randomized open label study. Urol Int. 2015;94(2):187-193.
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  45. Silvestri I, Cattarino S, Agliano A, et al. Effect of Serenoa repens (Permixon(R)) on the expression of inflammation-related genes: analysis in primary cell cultures of human prostate carcinoma. J Inflamm (Lond). 2013;10:11.
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  48. Al-Shukri SH, Deschaseaux P, Kuzmin IV, et al. Early urodynamic effects of the lipido-sterolic extract of Serenoa repens (Permixon(R)) in patients with lower urinary tract symptoms due to benign prostatic hyperplasia. Prostate Cancer Prostatic Dis. Nov 2000;3(3):195-199.
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  51. Gravas S, Samarinas M, Zacharouli K, et al. The effect of hexanic extract of Serenoa repens on prostatic inflammation: results from a randomized biopsy study. World J Urol. 2019 Mar;37(3):539-544
  52. Chiancone F, Carrino M, Meccariello C, Pucci L, Fedelini M, Fedelini P. The Use of a Combination of Vaccinium Macracarpon, Lycium barbarum L. and Probiotics (Bifiprost®) for the Prevention of Chronic Bacterial Prostatitis: A Double-Blind Randomized Study. Urol Int. 2019;103(4):423-426.
  53. Morgia G, Vespasiani G, Pareo RM, et al. Serenoa repens + selenium + lycopene vs tadalafil 5 mg for the treatment of lower urinary tract symptoms secondary to benign prostatic obstruction: a Phase IV, non-inferiority, open-label, clinical study (SPRITE study). BJU Int. 2018 Aug;122(2):317-325.
  54. Sudeep HV, Thomas JV, Shyamprasad K. A double blind, placebo-controlled randomized comparative study on the efficacy of phytosterol-enriched and conventional saw palmetto oil in mitigating benign prostate hyperplasia and androgen deficiency.  BMC Urol. 2020 Jul 3;20(1):86. 
  55. Yamada S, Shirai M, Ono K, Kageyama S. Beneficial Effects of Saw Palmetto Fruit Extract on Urinary Symptoms in Japanese Female Subjects by a Multicenter, Randomized, Double-Blind, Placebo-Controlled Study.  Nutrients. 2022 Mar 11;14(6):1190.
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  57. Zhang K, Guo RQ, Chen SW, et al. The efficacy and safety of Serenoa repens extract for the treatment of patients with chronic prostatitis/chronic pelvic pain syndrome: a multicenter, randomized, double-blind, placebo-controlled trial.  World J Urol. 2021 Sep;39(9):3489-3495. 
  58. Venkateswaran S, Declet-Bauzo R, Shodeinde M, Gilford P. Postoperative Retroperitoneal Hematoma: A Case of Saw Palmetto and the Importance of Primary Care Intervention. HCA Healthc J Med. 2020 Oct 29;1(5):279-28.
  59. Gammoudi R, Ameur K, Ouni B, et al. Fixed drug eruption to Serenoa repens: First case report and consideration of the use of herbal medicine.  Dermatol Ther. 2020 Nov;33(6):e14247. 
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