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Saw palmetto (Serenoa repens or Sabal serrulata) is a plant belonging to the palm tree family that is used in herbal medicine. Naturopaths and practitioners of alternative medicine contend that saw palmetto can treat a wide range of medical conditions. Chief among them is an enlarged prostate, although saw palmetto is also sometimes to treat infections, stress, and even hair loss.

This article looks at some of the conditions that saw palmetto is said to treat and the research behind the claims. It also offers tips on how to use saw palmetto safely as well as the possible risks and side effects of this popular herbal supplement.

In alternative medicine, saw palmetto is said to aid in the treatment of conditions such as asthma, colds, coughs, hair loss, migraine, chronic pelvic pain, and sore throat. Saw palmetto is also thought to increase libido (sex drive) as well as alleviate stress.

Saw palmetto is perhaps best known for its use in treating prostate problems. This include benign prostatic hyperplasia (an enlarged prostate) and prostatitis (prostate inflammation),

Scientific studies have provided limited evidence to support these claims.

One of the most common uses of saw palmetto is the treatment of benign prostatic hyperplasia (BPH), also known as an enlarged prostate. BPH is not considered a serious health issue, but it can cause significant symptoms, such as the increased need to urinate and urinary leakage. It can also increase the risk of urinary tract infections.

Several small studies have suggested that saw palmetto could benefit people with BPH. However, a report published in the Cochrane Database of Systematic Reviews in 2012 concluded that there was little evidence that palmetto could alleviate prostate inflammation or reduce BPH symptoms.

The Cochrane researchers analyzed 32 previously published studies involving 5,666 participants. They determined that saw palmetto neither improved urinary flow nor prostate size in men with BPH-related urinary tract symptoms.

Not all researchers have reached the same conclusions. A 2020 review published in the American Journal of Men's Health, which evaluated four studies involving 1,080 people with BPH, reported that saw palmetto taken daily for six months appeared to improve urinary flow (although there was no actual change in prostate size).

Despite the positive findings, the researchers noted that saw palmetto supplements were less effective than the drug Flomax (tamsulosin) commonly used to treat BPH.

Lab studies have shown that saw palmetto can block the action of 5-alpha-reductase, an enzyme involved in converting testosterone to a hormone called dihydrotestosterone . Dihydrotestosterone appears to play a role in the development of androgenic alopecia , a condition more commonly known as male-pattern hair loss.

While the current research is limited, there is some evidence that it may help treat this specific form of hair loss.

In a pilot study published in the Journal of Alternative and Complementary Medicine in 2002, a group of males with mild to moderate male-pattern hair loss showed a "highly positive" response when taking saw palmetto and a plant-based steroid called beta-sitosterol . The study attributed the results to saw palmetto's inhibition of 5-alpha reductase.

A 2020 review of studies in Skin and Appendage Disorders reached a similar verdict but noted that a lack of quality studies limited the conclusions.

Emerging research suggests that saw palmetto may benefit people with chronic pelvic pain syndrome (CPPS). CPPS is defined as pain below the belly button and between the hips that lasts six months or longer, often with no known cause.

A small study published in Urologia Internationalis in 2010 reported that saw palmetto provided relief of CPPS symptoms when combined with a proprietary supplement containing selenium and lycopene. It is unclear which of the supplements was responsible for the effect and further research is needed.

Saw palmetto is said to treat a wide range of unrelated medical conditions, including an enlarged prostate, male-pattern hair loss, and chronic pelvic pain. The evidence supporting these claims is generally lacking.

Saw palmetto can theoretically influence sex hormone levels, including estrogen and testosterone. Because of this, people with hormone-sensitive cancers (including breast cancer and prostate cancer) should consult with their oncologist before using saw palmetto.

Some men have also reported erectile dysfunction, breast tenderness, gynecomastia (breast enlargement), and a loss of libido (sex drive) while taking saw palmetto.

People on blood thinners such as Coumadin (warfarin) and Plavix (clopidogrel) should avoid saw palmetto as it may increase the risk of bleeding. For this same reason, saw palmetto should be stopped at least two weeks before or after surgery.

Children and pregnant women should not use saw palmetto due to the lack of safety research.

Saw palmetto can cause headache, fatigue, dizziness, stomach upset, nausea, or constipation in some people. It should not be used in children, people who are pregnant or breastfeeding, or those with hormone-sensitive cancers. It should also be avoided if you take blood thinners.

There is no recommended dose of saw palmetto. In studies evaluating the benefits of saw palmetto in people undergoing prostate surgery, a daily 320mg dose taken for two months was well tolerated with no significant side effects.

The appropriate dose of saw palmetto may vary based on your age, sex, and medical history. Speak to your healthcare provider before using supplements for medical reasons as there may be situations in which they pose more harm than good.

As a general rule, never take more than the recommended dose on the product label.

There is no recommended dose of saw palmetto. Speak with your doctor before using saw palmetto for medical reasons.

Saw palmetto supplements typically contain extracts of the fruit of the plant. You can purchase saw palmetto supplements online and in many natural food stores, drugstores, and stores specializing in herbal products.

Because nutritional supplements are not stringently regulated by the Food and Drug Administration (FDA), the quality can vary from one brand to the next.

If you choose to buy this or any supplement, the National Institutes of Health recommends that you read the Supplement Facts label. It contains valuable information every consumer should know, including the amount of active and inactive ingredients per serving (including fillers and binders you may be allergic to).

Opt for supplements that have been certified by U.S. Pharmacopeia (USP), ConsumerLab, or NSF International. Certification does not guarantee the product's safety or effectiveness but does provide assurance that the product was properly manufactured, contains the ingredients listed on the product label, and does not contain harmful levels of contaminants.

Because the quality of supplements can vary from one brand to the next, opt for those that have been evaluated by certifying bodies like U.S. Pharmacopeia, NSF International, or ConsumerLab. Certification provides assurance of a supplement's purity.

Saw palmetto is a plant belonging to the palm tree family that is used for herbal medicine. It is thought to prevent or treat a host of unrelated health conditions, including prostate problems, male-pattern hair loss, chronic pelvic pain, asthma, colds, and fatigue. The scientific evidence supporting these claims is generally weak.

Saw palmetto supplements are usually well tolerated but may cause headache, dizziness, nausea, constipation, or upset stomach in some people. Saw palmetto should not be used in children, people who are pregnant or breastfeeding, or those with hormone-sensitive cancers. It should also be avoided if you take blood thinners.

There is no recommended dose for saw palmetto. Speak with your doctor before using any supplement for medical reasons.

Common side effects of saw palmetto include bad breath, stomach upset, diarrhea, nausea, vomiting, headache, dizziness, and fatigue.  In rare cases, saw palmetto has been known to cause erectile dysfunction, loss of sex drive, and abnormally enlarged breasts in males.

While saw palmetto has traditionally been used to treat benign prostatic hyperplasia (BPH) in men, it is safe for women to take. However, women who are pregnant or breastfeeding should not take saw palmetto. 

Research suggests saw palmetto may influence male and female sex hormones, including androgen, estrogen, and testosterone. However, it is unclear whether saw palmetto has a measurable effect on hormone levels in humans.  

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Tacklind J1, Macdonald R, Rutks I, Stanke JU, Wilt TJ. Serenoa repens for benign prostatic hyperplasia. Cochrane Database Syst Rev. 2012 Dec 12;12:CD001423. doi:10.1002/14651858.CD001423.pub3

Cai T, Cui Y, Yu S, Li Q, Zhou Z, Gao Z. Comparison of Serenoa repens with tamsulosin in the treatment of benign prostatic hyperplasia: a systematic review and meta-analysis. Am J Mens Health. Mar-Apr 2020;4(2):1557988320905407. doi:10.1177/1557988320905407

Prager N1, Bickett K, French N, Marcovici G. A randomized, double-blind, placebo-controlled trial to determine the effectiveness of botanically derived inhibitors of 5-alpha-reductase in the treatment of androgenetic alopecia. J Altern Complement Med. 2002 Apr;8(2):143-52. doi:10.1089/acm.2002.8.143

Evron E, Juhasz, Babadjouni A, Mesinkovska NA. Natural hair supplement: friend or foe? Saw palmetto, a systematic review in alopecia. Skin Appendage Disord. 2020 Nov;6(6):329–37. doi:10.1159/000509905

Morgia G, Mucciardi G, Galì A, et al. Treatment of chronic prostatitis/chronic pelvic pain syndrome category IIIA with Serenoa repens plus selenium and lycopene (Profluss) versus S. repens alone: an Italian randomized multicenter-controlled study. Urol Int. 2010;84(4):400-6. doi:10.1159/000302716

Agbabiaka TB, Pittler MH, Wider B, Ernst E. Serenoa repens (saw palmetto): a systematic review of adverse events. Drug Saf. 2009;32(8):637-47. doi:10.2165/00002018-200932080-00003

National Center for Complementary and Integrative Health. Saw palmetto.

Fagelman E, Lowe FC. Saw palmetto berry as a treatment for BPH. Rev Urol. 2001 Summer;3(3):134-8.

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