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Complementary & Alternative Medicine
Index of Herbal Medicines, Supplements and Therapies
The decision to use products containing or claiming to contain saw palmetto should be carefully considered.
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.
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.
Prostatitis/chronic pelvic pain syndrome
Currently, it is not clear if saw palmetto can be used to treat prostatitis, or inflammation of the prostate. More studies are needed before a firm conclusion can be made.
Urinary tract disorders (in males)
Saw palmetto may be somewhat effective for treating urinary disorders. However, studies have produced inconsistent results. There is a need for well-designed studies of saw palmetto as a treatment for lower urinary tract symptoms.
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)
Breast size (to increase)
Enhanced physical performance
Excess hair growth
High blood pressure
Lactation (to increase)
Muscle or intestinal spasms
Pelvic congestive syndrome
Polycystic ovarian disease
Reproductive organ problems
Sperm production (to increase)
Upper respiratory tract infection
People who are allergic to saw palmetto or any of the chemicals in saw palmetto should avoid its use.
Scientific studies report that a few people using saw palmetto may experience mild gastrointestinal discomfort, erectile dysfunction, mild headache, dizziness, insomnia, fatigue, depression, stomach upset, breathlessness, fast heart rate, dry mouth, bad breath, nausea, constipation, vomiting, diarrhea, ulcer, liver inflammation, yellowing of the skin (jaundice), rash, loss of libido (sex drive), urinary tract infection and muscle pain. There are two reports of bleeding, which stopped shortly after the patients stopped using saw palmetto. Therefore, you may need to stop taking saw palmetto before some surgeries; discuss this with a health care professional. Be aware that many tinctures contain high levels of alcohol and should be avoided when driving or operating heavy machinery.
Lipidosterolic extract of Serenoa repens (LSESR) may be a better tolerated formulation, however this claim has not been confirmed.
PC-SPES is a combination herbal product that contains saw palmetto. The U.S. Food and Drug Administration has issued a warning not to use PC-SPES because it may contain the anticoagulant chemical warfarin and may cause bleeding.
Avoid saw palmetto if you have bleeding disorders, gastrointestinal disorders, or hormone-sensitive conditions. Because saw palmetto may increase blood pressure, avoid if you have high blood pressure or are on blood pressure medications.
Pregnancy And Breast-Feeding
Because of possible hormonal activity, saw palmetto extract is not recommended for women who are pregnant or 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
Saw palmetto should not be taken with drugs that affect the levels of male sex hormones (androgens), such as finasteride (Proscar) or flutamide (Eulexin). In theory, saw palmetto may interfere with birth control pills or hormone replacement therapy in women. There is one report of bleeding in a person using saw palmetto, and caution should be taken by people using drugs that may increase the risk of bleeding. The combination herbal product PC-SPES, which includes saw palmetto, also contains warfarin, an anticoagulant. There is a serious risk of bleeding if you use PC-SPES with other drugs that increase the risk of bleeding. Examples include warfarin (Coumadin), heparin and clopidogrel (Plavix). Some pain relievers may also increase the risk of bleeding, such as aspirin, ibuprofen (Motrin, Advil) and naproxen (Naprosyn, Aleve, Anaprox).
Be aware that many tinctures contain high levels of alcohol and may cause nausea or vomiting when taken with metronidazole (Flagyl) or disulfiram (Antabuse).
Avoid if taking blood pressure medication.
Because saw palmetto may have anti-inflammatory properties, avoid if taking any anti-inflammatory drugs, including non-steroidal anti-inflammatories (NSAIDS) and COX inhibitors.
Saw palmetto may inhibit cell proliferation and enhance immune function. Therefore, use saw palmetto cautiously if taking anti-proliferative or immune-enhancing medications.
Saw palmetto may have anti-bacterial properties, and may interact with other anti-bacterial agents and antibiotics.
If pregnant or breastfeeding, avoid saw palmetto as it may affect genital development. Tinctures may also contain alcohol, which should also be avoided if breastfeeding or pregnant.
Interactions With Herbs And Dietary Supplements
In theory, saw palmetto may interfere with the effects of herbs that have estrogenlike properties, such as red clover
or soy. Saw palmetto or PC-SPES may increase the risk of bleeding when taken with products such as Ginkgo biloba
). The tannins that may be present in saw palmetto may prevent the absorption of iron in the body.
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.
Standardized extracts of saw palmetto containing 80 to 95 percent sterols and fatty acids (liposterolic content) have been recommended.
Adults (Aged 18 Or Older)
Tablets/capsules: A dose of 160 milligrams twice daily or 320 milligrams daily (containing 80 percent to 90 percent liposterolic content) for up to 11 months has been taken by mouth. Higher doses may be used under medical supervision
Berries: A dose of one to two grams of ground, dried or whole berries daily has been taken by mouth.
Tincture: A dose of two to four milliliters (1:4) three times daily has been taken by mouth.
Fluid extract of berry pulp: A dose of one to two milliliters (1:1) three times daily has been taken by mouth.
Rectal suppositories: A dose of 640 milligrams once daily has been used. It is not clear if rectal use of saw palmetto is better than taking saw palmetto by mouth.
Tea: Tea made from berries may not be effective because the proposed active ingredient does not dissolve in water.
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.
- Natural Standard: An organization that produces scientifically based reviews of complementary and alternative medicine (CAM) topics
- 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
Natural Standard has reviewed all of the currently available medical literature to prepare the professional monograph from which this version was created.
Some of the more recent studies are listed below:
- Aliaev IuG, Vinarov AZ, Lokshin KL, Spivak LG. [Efficiency and safety of prostamol-Uno in patients with chronic abacterial prostatitis] Urologiia. 2006 Jan-Feb;(1):47-50. Russian.
- Avins AL, Bent S. Saw palmetto and lower urinary tract symptoms: what is the latest evidence? Curr Urol Rep. 2006 Jul;7(4):260-5. Review.
- 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.
- 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.
- Engelmann U, Walther C, Bondarenko B, Funk P, Schlδfke S. Efficacy and safety of a combination of sabal and urtica extract in lower urinary tract symptoms. A randomized, double-blind study versus tamsulosin. Arzneimittelforschung. 2006;56(3):222-9.
- 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.
- Gordon AE, Shaughnessy AF. Saw palmetto for prostate disorders. Am Fam Physician 2003;Mar 15, 67(6):1281-1283. Review.
- Kaplan SA, Volpe MA, Te AE. A prospective, 1-year trial using saw palmetto versus finasteride in the treatment of category III prostatitis/chronic pelvic pain syndrome. J Urol. 2004 Jan;171(1):284-8.
- Shoskes DA. Phytotherapy in chronic prostatitis. Urology 2002;Dec, 60(6 Suppl):35-37. Discussion, 37. Review.
- Lopatkin NA, Sivkov AV, Medvedev AA, Walter K, Schlefke S, Avdeĭchuk IuI, Golubev GV, Mel'nik KP, Elenberger NA, Engelman U. [Combined extract of Sabal palm and nettle in the treatment of patients with lower urinary tract symptoms in double blind, placebo-controlled trial] Urologiia. 2006 Mar-Apr;(2):12, 14-9. Russian.
- Magri V, Trinchieri A, Pozzi G, Restelli A, Garlaschi MC, Torresani E, Zirpoli P, Marras E, Perletti G. Efficacy of repeated cycles of combination therapy for the eradication of infecting organisms in chronic bacterial prostatitis. Int J Antimicrob Agents. 2007 May;29(5):549-56. Epub 2007 Mar 2.
- Natural Standard Research Collaboration, Chief Editors: Ulbricht C, Basch E, Natural Standard Herb and Supplement Reference - Evidence-Based Clinical Reviews, USA: Elsevier/Mosby, 2005.
- Shoskes DA.Phytotherapy and other alternative forms of care for the patient with prostatitis. Curr Urol Rep 2002;Aug, 3(4):330-334.
- 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 September 03, 2008
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