Saw palmetto is an alternative medicine that has proven effective at treating men bothered by the symptoms of benign prostatic hyperplasia, or an enlarged prostate. Clinical trials have shown that men with BPH may see an improvement with urinary difficulties and nighttime urination when taking saw palmetto, according to the National Institutes of Health. Although it is considered safe when used as directed, some men may develop unwanted and bothersome side effects.
Some men taking saw palmetto supplements to treat BPH have reported experiencing erectile dysfunction, according to the National Institutes of Health. Additionally, some men have experienced a decrease in sexual desire when taking the herb.
Breast tenderness and, in some cases, swelling of the breasts has also been reported by some men using saw palmetto supplements, according to the National Center for Complementary and Alternative Medicine.
Prostate Cancer Diagnosis
Because of how saw palmetto works in the body, it is possible that using the supplement could lower a man's prostate specific antigen level, although no test in humans has conclusively demonstrated this effect. PSA levels are one indicator of prostate cancer, so any lowered readings could delay a prostate cancer diagnosis, according to the National Institutes of Health.
Stomach upset can develop in some people using saw palmetto, although taking the supplement with food can decrease the likelihood of experiencing this side effect, according to the National Institutes of Health. Some men have also reported experiencing nausea, vomiting, diarrhea and constipation while using saw palmetto.
Saw palmetto may interfere with how the body normally responds to the sex hormones—testosterone and estrogen. Because of this, men taking hormone medications should not use saw palmetto supplements.
One case of severe bleeding during surgery has been tied to usage of saw palmetto supplements; using the herb may increase a man's chances of experiencing severe bleeding during surgery, according to the University of Maryland Medical Center. Because of the risk, men taking blood-thinning drugs and those with bleeding disorders should not take saw palmetto. Men who are taking saw palmetto should advise their doctor before undergoing surgical procedures.