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Herbal Medicine                                            
Saw Palmetto (Serenoa repens)

Be aware that the U.S. Food and Drug Administration does not strictly regulate herbs and dietary supplements. There is no guarantee of strength, purity or safety of products containing or claiming to contain saw palmetto. Decisions to use herbs or supplements should be carefully considered. Individuals using prescription drugs should discuss taking herbs or supplements with a pharmacist or health care professional before starting.


Scientists have studied saw palmetto for the following health problems:

Benign prostatic hypertrophy (prostate enlargement)
More than 30 small, poorly designed studies suggest that saw palmetto extract may improve symptoms of benign prostatic hypertrophy, such as urine flow and burning with urination, and may reduce the number of times per night that a man with this problem has to urinate. Early evidence suggests that saw palmetto extract may be as effective as the drug finasteride (Proscar), with fewer side effects. Because of problems with the way these studies are designed, the results are not fully convincing. Better studies are underway that may provide more definitive answers in the future. Most research has used the saw palmetto extract product Permixon.
Prostate cancer
There is not enough scientific evidence to recommend the product PC-SPES (which contains saw palmetto) for prostate cancer. PC-SPES also contains seven other herbs (Chrysanthemum morifolium, Isatis indigotica, Glycyrrhiza glabra, Ganoderma lucidum, Panax pseudo-ginseng, Rabdosia rubescens and Scutellaria baicalensis). It has been a popular treatment for prostate cancer, but the U.S. Food and Drug Administration has issued a warning not to use PC-SPES because it contains the anticoagulant chemical warfarin and may cause bleeding.
Neurogenic bladder (loss of bladder tone)
There are no good scientific studies using saw palmetto extract alone to treat neurogenic bladder.
Alopecia (hair loss)
One scientific study suggests that saw palmetto extract reduces hair loss caused by hormonal changes and aging. More studies are necessary before saw palmetto can be recommended for this use.

Unproven Uses    

Saw palmetto has been suggested for many other uses, based on tradition or on scientific theories. However, these uses have not been thoroughly studied in humans, and there is limited scientific evidence about safety or effectiveness. Some of these suggested uses are for conditions that are potentially very serious and even life-threatening. You should consult a health care professional before taking saw palmetto for any unproven use.

Breast size (to decrease)
Chronic pelvic pain syndrome
Chronic prostatitis
Enhanced physical performance
Epstein-Barr virus
Hair loss
High blood pressure
Lactation (to increase)
Menstrual pain
Migraine headache
Ovarian cysts
Polycystic ovarian disease
Reproductive organ problems
Sperm production (to increase)
Testicular atrophy

Potential Dangers    


Side Effects

Pregnancy And Breast-Feeding


Interactions with drugs, supplements and other herbs have not been thoroughly studied. The interactions listed below have been reported in scientific publications. If you are taking prescription drugs, speak with a health care professional or pharmacist before using herbs or dietary supplements.

Interactions With Drugs

Interactions With Herbs And Dietary Supplements


The doses listed below are based on scientific research, publications or traditional use. Because most herbs and supplements have not been thoroughly studied or monitored, safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients even within the same brand. Combination products often contain small amounts of each ingredient and may not be effective. Appropriate dosing should be discussed with a health care professional before starting therapy; always read the recommendations on a product's label. The dosing for unproven uses should be approached cautiously, because scientific information is limited in these areas.

One small study examining amounts of saw palmetto contained in preparations compared with amounts stated on labels reported a -97 percent to 140 percent difference. Half of the samples (three samples) contained less than 25 percent of the stated amount. Although this study examined very few saw palmetto samples, it is still a noteworthy example of a lack of quality assurance. Note that stomach upset caused by saw palmetto may be reduced by taking it with food.

Adults (Aged 18 Or Older)

Children (Younger Than 18): There is not enough evidence to recommend saw palmetto for children.


Saw palmetto extract has been suggested for many conditions, but it has been most studied as a treatment for benign prostatic hypertrophy (prostate enlargement). Although most research suggests effectiveness, higher-quality studies are needed before a firm conclusion can be made. Saw palmetto may interact with drugs that affect hormone levels, including some prostate cancer drugs. Women who are pregnant, breast-feeding, using birth control pills or taking hormone replacement therapy should avoid saw palmetto. Saw palmetto may increase the risk of bleeding and should be stopped before some surgeries. Consult a health care professional immediately if you have side effects. The combination herbal product PC-SPES, which includes saw palmetto, should be avoided because it contains the anticoagulant warfarin.

The information in this monograph was prepared by the professional staff at Natural Standard, based on thorough systematic review of scientific evidence. The material was reviewed by the Faculty of the Harvard Medical School with final editing approved by Natural Standard.


  1. Natural Standard: An organization that produces scientifically based reviews of complementary and alternative medicine (CAM) topics
  2. National Center for Complementary and Alternative Medicine (NCCAM): A division of the U.S. Department of Health & Human Services dedicated to research

Selected Scientific Studies: Saw Palmetto

Some of the more recent studies are listed below:

  1. Boyle P, Robertson C, Lowe F, et al. Meta-analysis of clinical trials of Permixon in the treatment of symptomatic benign prostatic hyperplasia. Urology 2000;55(4):533-539.
  2. Braeckman J, Bruhwyler J, Vanderkerckhove K, et al. Efficacy and safety of the extract of Serenoa repens in the treatment of benign prostatic hyperplasia: therapeutic equivalence between twice and once daily dosage forms. Phytother Res 1997;11:558-563.
  3. Braeckman J. A double-blind, placebo-controlled study of the plant extract Serenoa repens in the treatment of benign hyperplasia of the prostate. Eur J Clin Res 1997;9:247-259.
  4. de la TA, Buttyan R, Hayek O, et al. Herbal therapy PC-SPES: in vitro effects and evaluation of its efficacy in 69 patients with prostate cancer. J Urol 2000;164(4):1229-1234.
  5. Feifer AH, Fleshner NE, Klotz L. Analytical accuracy and reliability of commonly used nutritional supplements in prostate disease. J Urol 2002;Jul, 168(1):150-154. Discussion, 154.
  6. Gordon AE, Shaughnessy AF. Saw palmetto for prostate disorders. Am Fam Physician 2003;Mar 15, 67(6):1281-1283. Review.
  7. Shoskes DA. Phytotherapy in chronic prostatitis. Urology 2002;Dec, 60(6 Suppl):35-37. Discussion, 37. Review.
  8. Shoskes DA.Phytotherapy and other alternative forms of care for the patient with prostatitis. Curr Urol Rep 2002;Aug, 3(4):330-334.
  9. Talpur N, Echard B, Bagchi D, et al. Comparison of saw palmetto (extract and whole berry) and cernitin on prostate growth in rats. Mol Cell Biochem 2003;Aug, 250(1-2):21-26.

Last updated July 14, 2005