Saw Palmetto: What are the side effects?

Saw Palmetto Side Effects

Saw palmetto (serenoa repens) is a natural herbal-based product commonly used for prostate problems in men and hair loss in men and women. 

A number of studies have suggested that saw palmetto can help hair loss. These studies are small and few in number. Nevertheless, countless numbers of patients turn to these natural products. Furthermore, because they are natural, most assume they are without side effects. The side effect profile of saw palmetto is not entirely clear. It is however known that saw palmetto affects hormones in the body, and risks of mood changes like depression and sexual dysfunction may be real (albeit low) risk.

A recent report provided additional evidence that this natural product might best be classified among chemicals and molecules that affect the hormone and endocrine system of the body (so called "endocrine disruptors"). A 2015 paper from Italy reported development of hot flashes in a 10-year-old girl using saw palmetto. When she stopped treatment, the hot flashes stopped. When she started back up again ("ie a rechallenge'), the hot flashes returned. However, 4 months after starting saw palmetto, the 10 year old got her first menstrual cycle. 

This report reminds us that use of saw palmetto requires counselling of at least the low possibility of side effects. I advise my own patients of the generally well tolerated nature of saw palmetto but remind them of possible risks of mood changes and even the rare possibilities of sexual side effects. More studies are needed to not only document the successes of saw palmetto in medicine but the incidence of side effects.
 

Reference

Morabito et al. Pharmacology 2015.