Prostate Home > Saw Palmetto

Often used in supplements, saw palmetto is an herb that is used for treating prostate problems, such as an enlarged prostate. When the effectiveness of the herbal supplement was evaluated, some studies showed that it was effective, while others suggested that it was no more effective than a placebo. Side effects of saw palmetto may include nausea, decreased sex drive, and constipation.

What Is Saw Palmetto?

Saw palmetto (Serenoa repens) is an herbal supplement often used for prostate problems. In particular, it is usually used to help relieve the symptoms of an enlarged prostate (also known as benign prostatic hyperplasia or BPH).
(Click Uses of Saw Palmetto for more information, including additional uses.)

How Does It Work?

There are several different ideas about how the supplement might work. One theory suggests that it may work by inhibiting an enzyme called 5-alpha-reductase, blocking the conversion of testosterone into DHT (dihydrotestosterone), thereby decreasing the amount of DHT in the body. Since DHT is important for enlargement of the prostate, this may be how saw palmetto works for BPH. In fact, several prescription medications for enlarged prostate work in a similar way. Since these prescription medications are also effective for hair loss (particularly male pattern baldness), it is possible that saw palmetto may also work for hair loss.
Saw palmetto may also inhibit a few different growth factors (proteins in the body that encourage cell growth) and may also have anti-inflammatory properties. Some researchers think that the supplement may work by slowing down the growth of prostate cells or decreasing inflammation.

Is It Effective?

Many studies have evaluated the effectiveness of saw palmetto for an enlarged prostate, and the results have been mixed. Some studies indicated that it worked well, while other studies suggested that it was no more effective than a placebo (a "sugar pill" with no active ingredients).
There is not enough evidence to evaluate the effectiveness of the supplement for any other use.
(Click Does Saw Palmetto Work? for more information.)
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
Last updated/reviewed:
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