Saw Palmetto (Serenoa repens)

Saw Palmetto: Medical Uses

Saw palmetto is used for benign prostatic hyperplasia (BPH), stages I and II.

Historical Uses

Saw palmetto berries were used by Native Americans for food and for medicinal effects. Traditional use has been as a tonic for men.


Saw palmetto is a short palm tree with sharp leaves that flourishes in the southern United States. Berries appear at the end of the summer months, and they turn a purplish black color. Saw palmetto is difficult to cultivate.

Part Used

• Fruit (berries)

Major Chemical Compounds

• Free fatty acids

• Sitosterols

Saw Palmetto: Clinical Uses

Saw palmetto is used for benign prostatic hyperplasia (BPH), stages I and II.

Mechanism of Action

Saw palmetto inhibits the conversion of testosterone to dihydrotestosterone (as does finasteride [Proscar], a drug prescribed for treating BPH). It also speeds the breakdown and elimination of other hormones that are responsible for prostate enlargement. It reduces inflammation and fluid accumulation by a nonhormonal mechanism that does not affect serum prostate-specific antigen (PSA) levels, thereby limiting the risk that treatment could mask the development of prostate cancer. Saw palmetto also has androgenic and anti-prostatitic activity.

Saw Palmetto: Dosage

Standardized extract: 160 mg twice daily or 320 mg of standardized extract daily for BPH. It is standardized to 85 to 95 percent fatty acids and sterols. Results are usually noted in 30 days. Continue for 4 to 6 months with follow-up by primary care provider if medication needs to continue on a long-term basis. Saw palmetto does not interfere with results of PSA tests.

Side Effects

Saw palmetto may cause mild stomach upset.


• Saw palmetto is not recommended for patients with bacterial prostatitis.

Herb-Drug Interactions

Saw palmetto may decrease iron absorption.

Pregnancy and Breast-Feeding

Saw palmetto is safe when used appropriately.

Pediatric Patients

Saw palmetto is not recommended for children.

Summary of Studies

Marks et al. (2000). In this controlled, 6-month trial (an American study), 44 subjects took a blend of saw palmetto extract, nettle root extract, and pumpkin seed oil (Nutrilite, product of Amway) for BPH symptoms Results: symptoms improved, but not to a statistically significant degree. The saw palmetto combination product slowed the growth of prostate tissue via a nonhormonal mechanism without affecting serum PSA levels.

Overmyer (1999). A randomized, double-blind, placebo-controlled clinical trial used saw palmetto extract for 44 men with BPH. Results: Saw palmetto was beneficial in reducing swelling of prostate tissues by an unidentified nonhormonal mechanism in patients with BPH without affecting PSA levels.

Wilt et al. (1998). This meta-analysis of 18 studies (16 double-blind, placebo-controlled trials lasting 30 days to 48 weeks) involved 2939 men who had symptomatic BPH. Results: Compared to placebo, saw palmetto was associated with a lower frequency of nighttime urination and an improvement in peak urine flow. When saw palmetto was compared to Proscar, saw palmetto subjects said that adverse effects were mild and infrequent and erectile dysfunction was lower. Side effects of saw palmetto were f. f percent and those of Proscar were 4.9 percent.

Braeckman (1994). An uncontrolled, open trial of 505 patients with BPH lasted for 3 months. Patients were given i60 mg of saw palmetto b.i.d. for 3 months. After 90 days of treatment, 88 percent of patients and doctors said that therapy was effective. Side effects were reported in 5 percent of patients.

Romics et al. (1993). An uncontrolled clinical trial of 42 subjects lasted 12 months. Patients were given 160 mg of saw palmetto for 12 months. Results: Symptoms improved without side effects.

DiSilverio et al. (1992). In this double-blind, placebo-controlled study, 35 patients with BPH were randomized into two groups. Results: Saw palmetto has more of an antiestrogenic effect and less of an antiandrogenic effect.

Smith et al. (1986). This double-blind comparison involved Permixon (trade name of saw palmetto) 160 mg q.d. Results: Saw palmetto produced significant improvement in flow rate and BPH symptoms compared to placebo results.

Champault, G. (1984). This double-blind, placebo-controlled study included 94 patients with BPH for 30 days. Permixon at 80 mg b.i.d. was well tolerated with fewer side effects. Side effects were minor (e.g., headache). There were no changes in laboratory test results.

Schneider, H., Masuhr, T., (1995). A prospective, longitudinal, observational study of 2080 patients with BPH used saw palmetto. Results: Symptomatic, improvement was reported in 86 percent of subjects and improved quality of life was reported by 80 percent. Among physicians, 87 percent reported efficacy as very good or good.

Saw Palmetto: Warnings

  • • Saw palmetto may cause mild stomach upset.
  • • Don’t take saw palmetto if you have bacterial prostatitis.
  • • This herb may decrease iron absorption.
  • • Saw palmetto is safe during pregnancy and breast-feeding when used appropriately.
  • • It isn’t recommended for children.