What adverse effects are associated with saw palmetto supplementation?

Saw Palmetto Side Effects

Saw palmetto's primary adverse effects include increased bleeding risk, gastrointestinal disturbances (particularly acute pancreatitis), and potential hepatotoxicity, with the most clinically significant concern being perioperative bleeding complications. 1

Bleeding and Coagulation Effects

• Saw palmetto decreases platelet aggregation and may increase bleeding time, requiring discontinuation 2 weeks before any surgical procedure 1
• The mechanism involves cyclooxygenase inhibition demonstrated in animal models, though the exact pathway remains incompletely understood 2
• Case reports document hematuria and coagulopathy (elevated PT, PTT, and INR) in patients using saw palmetto 3
• The antiplatelet effects are similar to other herbal supplements that inhibit thromboxane synthetase 1

Clinical Pitfall: Many patients do not consider herbal supplements as "real medications" and may fail to disclose saw palmetto use during preoperative assessments. Always specifically ask about herbal supplement use when obtaining medication histories. 2

Gastrointestinal and Pancreatic Toxicity

• Acute pancreatitis is a documented serious adverse effect of saw palmetto, with multiple case reports showing temporal relationships between use and pancreatitis development 4, 5, 6
• Patients typically present with epigastric pain, nausea, and markedly elevated pancreatic enzymes (lipase >39,000 mmol/L reported) 6
• The mechanism may involve estrogenic receptor stimulation leading to hypertriglyceridemia or hypercoagulable states causing pancreatic necrosis 5
• Symptoms resolve with discontinuation and recur with rechallenge, establishing causality 6
• Mild gastrointestinal effects including colicky abdominal pain are commonly reported 4

Hepatotoxicity

• Cholestatic hepatitis and acute hepatitis have been documented with saw palmetto use 6
• Transaminase elevations (AST >1,200, ALT >1,200) can occur, sometimes concurrent with pancreatitis 6
• The estrogen/antiandrogen properties of saw palmetto may contribute to hepatotoxic effects 5

Effects on Laboratory Values

• Saw palmetto may affect PSA levels through phytoestrogenic compounds, which is clinically relevant for prostate cancer screening 2
• Over 20% of men take saw palmetto, making this a common confounder in PSA interpretation 2
• No association has been found between saw palmetto use and actual prostate cancer risk in prospective cohort studies 7

Drug Interactions and Contraindications

• Saw palmetto should be held for 2 weeks before surgery due to bleeding risk, similar to other antiplatelet supplements 1
• The supplement may interact with warfarin and other anticoagulants, potentially altering INR 1, 3
• Patients with history of pancreatitis, hepatic disease, or bleeding disorders should avoid saw palmetto 4, 5, 6

Important Consideration: When patients present with unexplained myalgia while taking saw palmetto, consider alternative etiologies including concurrent statins or other myotoxic medications, as red yeast rice (often taken with saw palmetto) is a known cause of rhabdomyolysis. 2

Safety Profile Context

• While many studies document saw palmetto as generally safe for benign prostatic hyperplasia symptoms, serious adverse effects do occur 3, 4
• The lack of FDA regulation means no standardization of content, dose, or constituent ratios across commercial preparations 8
• Detailed medication histories including all over-the-counter and herbal supplements are essential to identify saw palmetto as a potential cause of adverse effects 5, 6