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NCCIH Clinical Digest

for health professionals

Spotlight on Saw Palmetto: What the Science Says

July 2019

Clinical Guidelines, Scientific Literature, Info for Patients: 
Spotlight on Saw Palmetto

saw palmetto
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Benign Prostatic Hyperplasia (BPH)

Although several small studies have suggested modest benefit of saw palmetto for treating symptoms of BPH, a large study evaluating high doses of saw palmetto and a Cochrane review found that saw palmetto was not more effective than placebo for treatment of urinary symptoms related to BPH. A single randomized controlled trial showed combination therapy of saw palmetto plus lycopene, selenium, and tamsulosin was more effective than single therapies alone.

What Does the Research Show?

  • A 2012 Cochrane review of 32 randomized controlled trials involving 5,666 men with BPH found that Serenoa repens, at two and three times the usual dose, provides no improvement in urinary flow measures or prostate size in men with lower urinary tract symptoms consistent with BPH.
  • A 2011 double-blind, placebo-controlled, randomized trial in 369 older men demonstrated that saw palmetto extract administered at up to three times the standard daily dose (320 mg) did not reduce the urinary symptoms associated with BPH more than placebo. In addition, a 2009 Cochrane review of nine trials concluded that saw palmetto has not been shown to be more effective than placebo for this use.
  • A 2014 randomized trial of 225 men with lower urinary tract symptoms and BPH examined the efficacy and tolerability of combination therapy between saw palmetto, lycopene, and selenium plus tamsulosin versus single therapies. The findings suggest that a combination therapy of saw palmetto, lycopene, selenium, and tamsulosin is more effective than single therapies in improving International Prostate Symptom Score and increasing maximum urinary flow rate. It was noted that after 6 months of treatment, the combination therapy significantly improved symptom scores compared with single therapy, and from 6 to 12 months, combination therapy demonstrated significant improvement in urine flow rate compared to tamsulosin alone. There were no reported treatment-related adverse events associated with combination therapy.
  • A 2018 phase IV, non-inferiority, open-label, clinical trial (SPRITE study) of 404 participants found that treatment with saw palmetto, selenium, plus lycopene (SeR-Se-Ly) was not inferior to tadalafil 5 mg for improving the International Prostate Symptom Score and maximum urinary flow rate in men with lower urinary tract symptoms.


  • Saw palmetto appears to be well-tolerated by most users. It may cause mild side effects, including stomach discomfort.
  • Saw palmetto does not appear to affect readings of prostate-specific antigen (PSA) levels, even when taken in higher-than-usual amounts.
  • Saw palmetto has not been shown to interact with medications.
  • Information on the safety of saw palmetto comes primarily from studies in men. Little is known about the safety or side effects of saw palmetto in women or children.


  • Agbabiaka TB, Wider B, Watson LK, et al. Concurrent use of prescription drugs and herbal medicinal products in older adults: a systematic review. Drugs Aging. 2017;34(12):891-905.
  • Tacklind J, MacDonald R, Rutks I, Stanke JU, Wilt TJ. Serenoa repens for benign prostatic hyperplasia. Cochrane Database of Systematic Reviews 2012, Issue 12. Art. No.: CD001423.
  • 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.
  • Morgia G, Russo GI, Voce S, et al. Serenoa repens, lycopene and selenium versus tamsulosin for the treatment of LUTS/BPH. An Italian multicenter double-blinded randomized study between single or combination therapy (PROCOMB trial). Prostate. 2014;74(15):1471-1480.
  • 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;122(2):317-325.

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