Drugs A - Z
Saw palmetto (Serenoa repens [Bartram] Small)
Generic Name: saw palmetto
CategoryHerbs & Supplements
American dwarf palm tree, Arecaceae (family), cabbage palm, dwarf palm, Elusan® Prostate, IDS 89, LSESR, PA 109, Palmae (family), palmetto scrub, palmier de l'amerique du nord (French), palmier nain (French), Permixon®, Prostagutt®, Prostaserine®, sabal, sabalfruchte (German), Sabal fructus, savpalme (Danish), saw palmetto berry, serenoa, Serona repens, Serenoa serrulata Hook F., SG 291, Strogen®, WS 1473, Zwegpalme.
Saw palmetto (Serenoa repens, Sabal serrulata) is used popularly in Europe for symptoms associated with benign prostatic hypertrophy (enlargement of the prostate). Although not considered standard of care in the United States, it is the most popular herbal treatment for this condition.
Historical use of saw palmetto can be traced in the Americas to the Mayans who used it as a tonic and to the Seminoles who took the berries as an expectorant and antiseptic.
Saw palmetto was listed in the United States Pharmacopeia from 1906 to 1917 and in the National Formulary from 1926 to 1950. Saw palmetto extract is a licensed product in several European countries.
Multiple mechanisms of action have been proposed, and saw palmetto appears to possess 5-α-reductase inhibitory activity (thereby preventing the conversion of testosterone to dihydrotestosterone). Hormonal/estrogenic effects have also been reported, as well as direct inhibitory effects on androgen receptors and anti-inflammatory properties.
EvidenceDISCLAIMER: These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Enlarged prostate (benign prostatic hypertrophy/BPH):
Numerous human trials report that saw palmetto improves symptoms of benign prostatic hypertrophy (BPH) such as nighttime urination, urinary flow, and overall quality of life, although it may not greatly reduce the size of the prostate. The effectiveness may be similar to the medication finasteride (Proscar®) with fewer side effects. Although the quality of these studies has been variable, overall they suggest effectiveness. Saw palmetto has not been thoroughly compared to other types of drugs used for BPH, such as doxazosin (Cardura®) or terazosin (Hytrin®). Most available studies have assessed the standardized saw palmetto product Permixon®.
Although a 2003 study by Willetts et al. reported no difference over a 12-week period and a 2006 well-designed study by Bent et al. reported no difference over a 12-month period, overall the weight of available scientific evidence favors the effectiveness of saw palmetto over placebo.
Male-pattern hair loss:
It has been suggested that saw palmetto may block some effects of testosterone and therefore reduce male pattern hair loss, similar to the medication finasteride (Propecia®). More studies are necessary before saw palmetto can be recommended for this use.
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 (FDA) has issued a warning not to use PC-SPES® because it contains the anticoagulant chemical warfarin and may cause bleeding.
Prostatitis/chronic pelvic pain syndrome (CP/CPPS):
A prospective, randomized, open label, one-year study was designed to assess the safety and efficacy of saw palmetto and finasteride in the treatment of men diagnosed with category III prostatitis/chronic pelvic pain (CP/CPPS). CP/CPPS treated with saw palmetto had no appreciable long-term improvement. In contrast, patients treated with finasteride had significant and durable improvement in multiple parameters except for voiding.
There is currently little information on the effectiveness of saw palmetto for the treatment of bladder disorders.
TraditionWARNING: DISCLAIMER: The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.
Acne, aphrodisiac, asthma, bladder inflammation, breast feeding, breast enlargement or reduction, bronchitis, cancer, catarrh, cough, cystitis, diabetes, diarrhea, digestive aid, diuretic, dysentery, Epstein-Barr virus, excess hair growth, expectorant, high blood pressure, hormone imbalances (estrogen or testosterone), immune stimulation, impotence, indigestion, inflammation, laryngitis, menstrual pain, migraine headache, muscle or intestinal spasms, ovarian cysts, performance enhancement, polycystic ovarian syndrome, postnasal drip, reproductive organ problems, sedation, sexual vigor, sore throat, sperm production, testicular atrophy, upper respiratory tract infection, uterine or vaginal disorders.
Adults (18 years and older)
For enlarged prostate (benign prostatic hypertrophy), a dose of 320 milligrams daily, in one dose or two divided doses (80% to 90% liposterolic content), has been used in numerous studies. Reports suggest that 160 milligrams once daily may be as effective as twice daily.
Traditional or other suggested doses that are less studied include: 1 to 2 grams of ground, dried, or whole berries daily; 2 to 4 milliliters of tincture (1:4) three times daily; 1 to 2 milliliters fluid extract of berry pulp (1:1) three times daily; or tea (2 teaspoons dried berry with 24 ounces water, simmered slowly until liquid is reduced by half) taken as 4 ounces three times daily. Teas prepared from saw palmetto berries are potentially not as effective because the active ingredients may not dissolve in water. Some experts believe that a preparation called lipidosterolic extract of Serenoa repens (LSESR) may cause fewer side effects.
Children (younger than 18 years)
Not enough information is available to recommend the use of saw palmetto in children.
SafetyDISCLAIMER: Many complementary techniques are practiced by healthcare professionals with formal training, in accordance with the standards of national organizations. However, this is not universally the case, and adverse effects are possible. Due to limited research, in some cases only limited safety information is available.
Few allergic symptoms have been reported with saw palmetto. A study of people taking the combination product PC-SPES® (no longer commercially available), which includes saw palmetto and seven other herbs, reports that three out of 70 people developed allergic reactions. In one case, the reaction included throat swelling and difficulty breathing.
Side Effects and Warnings
Few severe side effects of saw palmetto are noted in the published scientific literature. The most common complaints involve the stomach and intestines, and include stomach pain, nausea, vomiting, bad breath, constipation, and diarrhea. Stomach upset caused by saw palmetto may be reduced by taking it with food. Some reports suggest that there may be less abdominal discomfort with the preparation lipidosterolic extract of Serenoa repens (LSESR). A small number of reports describe ulcers or liver damage and yellowing of the skin (jaundice), but the role of saw palmetto is not clear in these cases. Similarly, reports of headache, dizziness, insomnia, depression, breathing difficulties, muscle pain, high blood pressure, chest pain, abnormal heart rhythm, and heart disease have been reported, but are not clearly caused by saw palmetto. People with health conditions involving the stomach, liver, heart, or lungs should use caution.
Caution is advised in people scheduled to undergo some surgeries or dental work, who have bleeding disorders, or who are taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.
Some men using saw palmetto report difficulty with erections, testicular discomfort, breast tenderness or enlargement, and changes in sexual desire. Saw palmetto may have effects on the body's response to the sex hormones estrogen and testosterone, but no specific effect has been well demonstrated in humans. Men or women taking hormonal medications (such as finasteride/Proscar®/Propecia® or birth control pills) or who have hormone-sensitive conditions should use caution. Tinctures may contain high levels of alcohol and should be avoided when driving or operating heavy machinery.
In theory, PSA (prostate specific antigen) levels may be artificially lowered by saw palmetto, based on a proposed mechanism of action of saw palmetto (inhibition of 5-α-reductase). Therefore, there may be a delay in diagnosis of prostate cancer or interference with following PSA levels during treatment or monitoring in men with known prostate cancer.
The combination product PC-SPES®, which contains saw palmetto and seven other herbs, has been found to contain prescription drugs including warfarin, a blood thinner. The U.S. Food and Drug Administration (FDA) has issued a warning not to use PC-SPES® for this reason, and it is no longer commercially available.
Pregnancy and Breastfeeding
Because of possible hormonal activity, saw palmetto extract is not recommended for women who are pregnant or breastfeeding. Many tinctures contain high levels of alcohol and should be avoided during pregnancy.
Interactions with Drugs
Saw palmetto may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®). Some batches of the discontinued combination herbal preparation PC-SPES®, which contains saw palmetto and seven other herbs, has been found to contain several medications including the "blood thinner" warfarin.
Saw palmetto should not be taken with drugs that affect the levels of male sex hormones (androgens), such as finasteride (Proscar®, Propecia®) or flutamide (Eulexin®). In theory, saw palmetto may interfere with birth control pills or hormone replacement therapy in women. Tinctures may contain high levels of alcohol and may cause nausea or vomiting when taken with metronidazole (Flagyl®) or disulfiram (Antabuse®).
Study in normal volunteers reveals no effects of saw palmetto on cytochrome P450 3A4 or 2D6 activity.
Interactions with Herbs and Dietary Supplements
Based on at least two reports of serious bleeding, saw palmetto may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.
Because saw palmetto may have activity on the body's response to estrogen, the effects of other agents believed to have estrogen-like properties may be altered.
Tannins in saw palmetto may prevent iron absorption.
This information is based on a professional level monograph edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com): Tracee Rae Abrams, PharmD (University of Rhode Island); Ethan Basch, MD, MSc, MPhil (Memorial Sloan-Kettering Cancer Center); Heather Boon, B.Sc.Phm, PhD (University of Toronto); Wendy Chao, PhD (Natural Standard Research Collaboration); Michelle Corrado, PharmD (Harvard Vanguard Medical Associates); Dawn Costa, BA, BS (Natural Standard Research Collaboration); Ivo Foppa, MD, ScD (University of South Carolina); Sadaf Hashmi MD, MPH (Johns Hopkins School of Hygiene and Public Health); Paul Hammerness, MD (Massachusetts General Hospital); Eileen Kingsbury, PharmD (University of Rhode Island); Michael Smith, M.R.PharmS, ND (Canadian College of Naturopathic Medicine); Philippe Szapary, MD (University of Pennsylvania); Shaina Tanguay-Colucci, BS (Natural Standard Research Collaboration); Catherine Ulbricht, PharmD (Massachusetts General Hospital); Minney Varghese, BS (Northeastern University); Mamta Vora, PharmD (Northeastern University); Wendy Weissner, BA (Natural Standard Research Collaboration); Jen Woods, BS (Natural Standard Research Collaboration).
BibliographyDISCLAIMER: Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.
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.
Bent S., Kane C., Shinohara K., et al. Saw palmetto for benign prostatic hyperplasia. N Engl.J Med 2-9-2006;354(6):557-566.
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.
Braeckman J, Denis L, de Leval J, et al. 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.
Descotes J, Rambeaud J, Deschaseaux P, et al. Placebo-controlled evaluation of the efficacy and tolerability of Permixon in benign prostatic hyperplasia after exclusion of placebo responders. Clin Drug Invest 1995;9(5):291-297.
Engelmann U, Walther C, Bondarenko B, et al. 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, et al. Analytical accuracy and reliability of commonly used nutritional supplements in prostate disease. J.Urol 2002;168(1):150-154.
Gerber GS, Zagaja GP, Bales GT, et al. Saw palmetto (Serenoa repens) in men with lower urinary tract symptoms: effects on urodynamic parameters and voiding symptoms. Urology 1998;51(6):1003-1007.
Gerber GS, Kuznetsov D, Johnson BC, et al. Randomized, double-blind, placebo-controlled trial of saw palmetto in men with lower urinary tract symptoms. Urology 2001;58(6):960-964.
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;171(1):284-288.
Magri V, Trinchieri A, Pozzi G, et al. 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.
Preuss HG, Marcusen C, Regan J, et al. Randomized trial of a combination of natural products (cernitin, saw palmetto, B-sitosterol, vitamin E) on symptoms of benign prostatic hyperplasia (BPH). Int Urol.Nephrol 2001;33(2):217-225.
Veltri RW, Marks LS, Miller MC, et al. Saw palmetto alters nuclear measurements reflecting DNA content in men with symptomatic BPH: evidence for a possible molecular mechanism. Urology 2002;60(4):617-622.
Willetts KE, Clements MS, Champion S, et al. A. Serenoa repens extract for benign prostate hyperplasia: a randomized controlled trial. BJU Int 2003;92(3):267-270.
Wilt TJ, Ishani A, Stark G, et al. Saw palmetto extracts for treatment of benign prostatic hyperplasia: a systematic review. JAMA 11-11-1998;280(18):1604-1609.
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.