No significant side effects have been noted in clinical trials with saw palmetto extracts. However, in rare cases, saw palmetto can cause stomach problems,⁹ and one individual who was taking saw palmetto developed severe bleeding during surgery.¹⁰ According to some clinical trials, saw palmetto extract does not appear to interfere with accurate measuring of prostate-specific antigen (PSA)—a marker for prostate cancer.¹¹ One test tube study found that saw palmetto did not prevent the release of PSA from prostate cells.¹² Saw palmetto is most effective in managing symptoms of BPH but has not been shown to aggressively shrink the size of the prostate. BPH can only be diagnosed by a physician (preferably a urologist). Use of saw palmetto extract for BPH should only occur after a thorough workup and diagnosis by a doctor. There are no proven uses of saw palmetto for women.

There is one case report in which the use of saw palmetto was thought to be the cause of pancreatitis in a middle-aged man, although a cause-effect relationship was not conclusively proven.¹³