Saw palmetto (Serenoa repens) is a plant belonging to the palm tree family. It is frequently used in complementary and alternative medicine to treat enlarged prostate, hair loss, chronic pelvic pain, and migraines. It is widely sold in the United States as a supplement to improve urinary health.
Despite its long-standing use in folk medicine, the evidence supporting the benefits of saw palmetto in treating or preventing any medical condition is weak. Even so, there is some evidence that certain compounds in saw palmetto may have medical uses. Eleutheroside 0.8%
This article takes an unbiased look at the possible uses and benefits of saw palmetto, as well as potential risks, side effects, and interactions you should be aware of.
For the purpose of this article, "male" refers to people with penises, and "female" refers to people with vaginas irrespective of the gender or genders they identify with.
Saw palmetto contains a variety of compounds that are thought to have medical benefits. Most are derived from the berry of the plant.
Saw palmetto is widely sold as a supplement in capsule, softgel, powder, and liquid extract forms. There are also oil-based saw palmetto serums that you can apply directly to the hair.
There is no recommended dose for saw palmetto in any form. The manufacturer-recommended dosage can vary dramatically with some recommending 160 milligrams (mg) per day and others recommending dosages as high as 4,800 mg per day. As a general rule, never exceeded the manufacturer's recommended daily dose.
Speak with your healthcare provider before taking any dietary supplement to ensure it is safe for you as an individual. Supplements should never be used as a substitute for treatments prescribed by a healthcare provider.
Saw palmetto is best known as an alternative or complementary treatment for benign prostatic hyperplasia (BPH), also known as an enlarged prostate. Compounds in saw palmetto are thought to improve lower urinary tract symptoms of BPH, including nocturia (nighttime urination), frequent urination, decreased urine flow, incomplete bladder emptying, and urinary urgency.
It is thought that phytosterols in saw palmetto help block the action of testosterone which may, in turn, ease prostate inflammation. Fatty acids like lauric acid have also been shown in test tube studies to block an enzyme called 5-alpha-reductase in the same way as the drug Flomax (tamsulosin), commonly used to treat enlarged prostate.
The evidence supporting the benefits of saw palmetto in treating or preventing BPH is lacking.
A 2020 analysis of four studies involving 1,080 adults with bPH concluded that saw palmetto taken daily for six months improved urinary flow as well as Flomax, however, it did not reduce the size of the prostate gland in the way that Flomax and other 5-alpha-reductase inhibitors do.
Of concern is the suggestion that testosterone somehow worsens BPH and that the suppression of testosterone will improve symptoms (a hypothesis referred to as "androgen saturation").
Studies show just the opposite. In fact, low testosterone (hypogonadism ) is an important risk factor for BPH and lower urinary tract symptoms.
Androgenic alopecia (AGA) refers to hair loss caused by an excessive response to testosterone. Sometimes referred to as male-pattern hair loss, androgenic alopecia can also affect females and is a characteristic feature of the hormonal disorder polycystic ovary syndrome (PCOS).
By suppressing androgens, saw palmetto is seen by some as an inexpensive and attractive alternative to prescription hair loss drugs like topical Rogaine (minoxidil) and oral Propecia (finasteride).
A 24-week study in the Australasia Journal of Dermatology—involving 50 males with mild to moderate AGA—reported that the daily application of saw palmetto serum to thinning hair improved the follicle count by the 12th week. The findings were limited by the small study size as well as the lack of a control group (participants who were given a placebo).
A two-year study conducted at the University of Rome in 2012 compared a daily 320-mg oral saw palmetto supplement to a daily 1-mg dose of Propecia for 100 males with mild to moderate AGA. When compared to the saw palmetto group, those who were given Propecia had better retention of hair on the top and frontal areas of the scalp.
Saw palmetto is thought by some to help treat a condition in males called chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). This is a condition of unknown origin that causes pelvic pain lasting for at least six months that is severe enough to limit your ability to function normally.
Some researchers contend that a fatty acid in saw palmetto, called palmitoylethanolamide PEA), has anti-inflammatory and analgesic (pain-relieving) effects that can benefit people with CP/CPPS.
A 2021 study published in the World Journal of Urology investigated the benefits of saw palmetto in 221 males with CP/CPPS, half of whom were given a daily 160-mg dose of saw palmetto and the other half of whom received a placebo. After 12 weeks, those given saw palmetto had lower overall pain scores than those given the placebo.
Findings from other studies have been inconsistent. Of five clinical trials included in a 2022 review of studies in the Asian Journal of Surgery, only one concluded that saw palmetto was beneficial to people with CP/CPPS. One reported worsening symptoms, while the remaining three showed no significant changes in pain symptoms.
The National Center for Complementary and Integrative Health (NCCIH) reports that saw palmetto is sometimes used as a treatment for migraine headaches.
There is not yet any good evidence to support this claim, and many studies investigating the use of saw palmetto report headache as a common side effect.
According to the NCCIH, "There isn’t enough research on saw palmetto for conditions other than BPH to allow any conclusions to be reached." With regards to BPH, the NCCIH states that "no saw palmetto product has been conclusively shown to be effective for BPH."
The U.S. Food and Drug Administration (FDA) regards dietary supplements like saw palmetto as generally safe for use. Side effects are uncommon and tend to be mild.
Possible side effects of saw palmetto include:
On rare occasions, males have reported erectile dysfunction, breast tenderness, gynecomastia (abnormal breast growth), and a loss of libido (sex drive) when using saw palmetto for a long period of time. This may be due to saw palmetto's suppressive effect on testosterone.
Precautions should be taken when considering the use of saw palmetto in the following groups:
When buying supplements, choose those that have been independently certified by third-party agencies like U.S. Pharmacopeia (USP), ConsumerLab, and NSF International. Certification does not mean that the product works but ensures that the ingredients on the product label are correct and uncontaminated.
The NCCIH states that saw palmetto has not been shown to interact with medications. Even so, there are theoretical risks you should be aware of:
The prostate-specific antigen (PSA) test is a blood test that can help identify problems with the prostate gland, including BPH and prostate cancer. According to the NCCIH, saw palmetto has no effect on a person's PSA levels when tested.
Saw palmetto is a plant belonging to the palm tree family that is thought to treat or prevent medical conditions like enlarged prostate, testosterone-related hair loss, and chronic pelvic pain. To date, the evidence supporting these claims is weak.
While generally safe for use, saw palmetto is not known to treat or prevent any medical condition.
National Center for Complementary and Integrative Health. Saw palmetto.
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By Trang Tran, PharmD Trang Tran, PharmD, is a pharmacist who is passionate about integrative health.
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