What are the adverse effects of saw palmetto?

Adverse Effects of Saw Palmetto

Saw palmetto may increase bleeding risk, requiring discontinuation 2 weeks before surgery, and can potentially cause gastrointestinal disturbances including pancreatitis, headache, and dizziness, though it is generally well-tolerated with minimal serious adverse effects. 1

Primary Adverse Effects

Bleeding Risk

• Saw palmetto is known to decrease platelet aggregation, potentially increasing bleeding time 2, 1
• May cause increased risk of hematuria and operative bleeding, particularly concerning in patients taking:
  • Anticoagulants
  • Antiplatelet medications
  • NSAIDs 1, 3
• A case report documented coagulopathy with elevated prothrombin time, partial thromboplastin time, and international normalized ratio in a patient using saw palmetto 3

Gastrointestinal Effects

• Gastrointestinal disturbances are among the most common side effects 1
• Serious gastrointestinal adverse effects include:
  • Acute pancreatitis (multiple case reports document this rare but serious adverse effect) 4, 5, 6
  • The mechanism may involve estrogen receptor stimulation or cyclooxygenase inhibition 6

Other Adverse Effects

• Headache and dizziness 1
• Potential hepatotoxicity (case reports of acute hepatitis) 5
• Possible hormonal effects due to phytoestrogenic compounds 1

Pre-Surgical Considerations

• Discontinue saw palmetto 2 weeks before any surgical procedure due to increased bleeding risk 1
• This is especially important for procedures with high bleeding risk
• Multiple medical societies and guidelines recommend this precaution 1

Drug Interactions

• Increased risk of bleeding when combined with:
  • Anticoagulants (warfarin, heparin, DOACs)
  • Antiplatelet agents (aspirin, clopidogrel)
  • NSAIDs 1
• May affect PSA levels, potentially complicating prostate cancer screening 1

Monitoring Recommendations

• Monitor for signs of bleeding in patients taking saw palmetto with anticoagulants
• Be alert for symptoms of pancreatitis (epigastric pain, nausea, vomiting) 4, 5, 6
• Consider liver function tests if hepatotoxicity is suspected 5

Efficacy Considerations

• Despite widespread use for benign prostatic hyperplasia (BPH) symptoms, efficacy remains questionable 7
• A rigorous randomized controlled trial found that even increasing doses of saw palmetto extract (up to 3 times the standard dose) was no more effective than placebo for lower urinary tract symptoms 7
• This limited efficacy should be weighed against the potential adverse effects when recommending use

Clinical Implications

• Always obtain a complete medication history including herbal supplements
• Advise patients about the potential risks, particularly bleeding risk
• Recommend discontinuation 2 weeks before surgical procedures
• Consider alternative treatments for BPH with better established safety and efficacy profiles