Saw Palmetto
Saw Palmetto
This information describes the common uses of Saw Palmetto, how it works, and its possible side effects.

Common Name

American dwarf palm tree, Cabbage palm

How It Works

Saw palmetto was shown in some studies to help relieve the symptoms of benign prostatic hypertrophy (BPH), but it has not been shown to prevent or treat prostate cancer.

Studies in the laboratory show that saw palmetto works by countering effects of male sex hormones such as testosterone and DHT. It appears to reduce levels of these hormones in body tissues like the prostate. Other studies have noted that saw palmetto reduces the conversion of testosterone to DHT, its more potent form. Saw palmetto berry extracts also reduce inflammation and swelling by preventing the formation of compounds that cause these reactions.

In a laboratory study, saw palmetto extract was found to slow the growth of normal prostate cells and increase their sensitivity to radiation, while not affecting prostate cancer cells. Since this may increase the risk of complications, patients should consult with a physician before using saw palmetto supplements during radiation therapy.

Purported Uses

  • To treat benign prostatic hypertrophy (BPH)
    Several clinical trials and meta-analyses have shown that saw palmetto improves urinary tract symptoms associated with BPH.
  • To treat prostate cancer
    Saw palmetto shows anti-inflammatory and anti-androgen properties in laboratory studies and reduces the levels of DHT in the prostate in clinical trials. However, it is not an effective treatment for prostate cancer.
  • To promote urination
    One study suggests an increase in urine flow, with an herbal combination formula including saw palmetto in addition to drug therapy.
  • As an anti-inflammatory
    Various studies suggest anti-inflammatory effects.

Do Not Take If

  • You are taking warfarin or other blood thinners: Saw palmetto may increase the risk of bruising and bleeding.
  • You are taking antiplatelets such as clopidogrel: Saw palmetto may increase the effects of these drugs.
  • You are taking nonsteroidal anti-inflammatory drugs (NSAIDs): Saw palmetto may increase the side effects of these drugs.
  • You are taking drugs that are substrates of UGT (uridine 5’-diphospho-glucuronosyltransferase): Saw palmetto may increase the risk of side effects of these drugs.
  • You are taking drugs that are substrates of cytochrome P450: Saw palmetto may increase the risk of side effects of these drugs.

Side Effects

Common: Gastrointestinal upset, diarrhea, fatigue, headache, decreased libido and rhinitis
Most effects are reported as mild and similar to effects with placebo.

Case reports

  • Potentially fatal blood accumulation around the heart: In a 76-year-old man taking a blood thinner for irregular heart rhythm who had also been taking saw palmetto. Although this condition appeared related to the use of his medication, saw palmetto may have contributed to this drug’s increased activity.
  • Severe bleeding during surgery
  • Blood in the urine and impaired blood clotting
  • Severe inflammation of the pancreas
  • Severe liver damage
  • Hot flashes and first menstrual cycle: Two cases in children who were treated with saw palmetto for hair disorders.