Saw palmetto
Saw palmetto


Saw palmetto (Serenoa repens) is a tree that grows up to 10 feet tall with thorn-shaped leaves arranged like a fan. Its ripe fruit is used to make medicine.

Saw palmetto seems to lower the amount of pressure on the tubes that carry urine in males. Saw palmetto also might prevent testosterone from being converted to a more potent form called dihydrotestosterone (DHT). Reduced levels of DHT might help prevent some types of hair loss.

People commonly use saw palmetto for symptoms of an enlarged prostate called benign prostatic hypertrophy (BPH). But it doesn't seem to improve this condition. Saw palmetto is also used to prevent complications from prostate surgery and for treating other prostate conditions, male-pattern baldness, sexual dysfunction, and many other purposes, but there is no good scientific evidence to support most of these uses.
When taken by mouth: Saw palmetto is likely safe when used for up to 3 years. Side effects are usually mild and might include dizziness, headache, nausea, and diarrhea.

When given rectally: Saw palmetto is possibly safe when used for up to 30 days. It's unknown if it is safe to use for longer periods of time.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Saw palmetto is likely unsafe when taken by mouth during pregnancy or breast-feeding. It acts like a hormone, and this could be dangerous. Don't use during pregnancy or breast-feeding.

Surgery: Saw palmetto might slow blood clotting. It might cause extra bleeding during and after surgery. Stop using saw palmetto at least 2 weeks before a scheduled surgery.


NatMed Pro rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
Likely effective Effectiveness definitions
Possibly effective Effectiveness definitions
  • A type of prostate surgery (transurethral resection of the prostate or TURP). Taking 320 mg of saw palmetto by mouth daily for 2 months before prostate surgery can improve surgery outcomes.
Likely ineffective Effectiveness definitions
Possibly ineffective Effectiveness definitions
  • Enlarged prostate (benign prostatic hyperplasia or BPH). Taking saw palmetto by mouth has little or no benefit for reducing BPH symptoms. Saw palmetto doesn't seem to reduce the need to go to the bathroom at night or reduce painful urination.
There is interest in using saw palmetto for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.
Insufficient evidence Effectiveness definitions

Dosing & administration

Saw palmetto has most often been used by adults in doses of 320-960 mg by mouth daily for up to 3 years. It's also been used in lotion. Speak with a healthcare provider to find out what type of product and dose might be best for a specific condition.

Interactions with pharmaceuticals

Birth control pills (Contraceptive drugs)

Interaction Rating=Moderate Be cautious with this combination.

Some birth control pills contain estrogen. Saw palmetto might decrease the effects of estrogen in the body. Taking saw palmetto along with birth control pills might decrease their effects. If you take birth control pills along with saw palmetto, use an additional form of birth control such as a condom.


Interaction Rating=Moderate Be cautious with this combination.

Saw palmetto seems to decrease estrogen levels in the body. Taking saw palmetto along with estrogen pills might decrease their effects.

Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)

Interaction Rating=Moderate Be cautious with this combination.

Saw palmetto might slow blood clotting. Taking saw palmetto along with medications that also slow blood clotting might increase the risk of bruising and bleeding.

Interactions with herbs & supplements

Herbs and supplements that might slow blood clotting: Saw palmetto might slow blood clotting and increase the risk of bleeding. Taking it with other supplements with similar effects might increase the risk of bleeding in some people. Examples of supplements with this effect include garlic, ginger, ginkgo, nattokinase, and Panax ginseng.

Interactions with foods

There are no known interactions with foods.
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This monograph was last reviewed on 31/07/2023 10:00:00 and last updated on 26/03/2022 08:45:52. Monographs are reviewed and/or updated multiple times per month and at least once per year.
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