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Cat's Claw Side Effects & Safety

Evidence:Emerging
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This content is for informational purposes only and does not constitute medical advice. Statements about dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary — consult your healthcare provider before starting any supplement. Full disclaimer

Safety Profile

Overall safety rating: Safe with Caution

Potential Side Effects

  • Gastrointestinal discomfort (nausea, diarrhea) in some users
  • Headache or dizziness (uncommon)
  • Hypotension at high doses
  • Contraindicated in autoimmune conditions without medical supervision due to immune-modulating effects

Drug & Supplement Interactions

  • Immunosuppressants — cat's claw may modulate immune function; use caution with transplant or autoimmune medications
  • Anticoagulants — may have mild antiplatelet effects; monitor with blood thinners
  • Antihypertensives — cat's claw may lower blood pressure; additive hypotensive effect possible
  • CYP3A4 substrates — may inhibit CYP3A4 enzyme, affecting drug metabolism

Maximum Dose

Do not exceed: Up to 350mg/day extract has been studied; traditional bark tea uses up to 4g dried bark daily

Full Cat's Claw Guide

References

  1. RCTMur E, Hartig F, Eibl G, Schirmer M (2002). Randomized double blind trial of an extract from the pentacyclic alkaloid-chemotype of Uncaria tomentosa for the treatment of rheumatoid arthritis. Journal of Rheumatology. PubMed
  2. RCTPiscoya J, Rodriguez Z, Bustamante SA, et al. (2001). Efficacy and safety of freeze-dried cat's claw in osteoarthritis of the knee: mechanisms of action of the species Uncaria guianensis. Inflammation Research. DOI PubMed
  3. Sandoval M, Okuhama NN, Zhang XJ, et al. (2002). Anti-inflammatory and antioxidant activities of cat's claw (Uncaria tomentosa and Uncaria guianensis) are independent of their alkaloid content. Phytomedicine. DOI PubMed
  4. Lopes AA, Coppede JDS, Amatto PPG, Aragon DC, et al. (2025). Cytotoxic effect of different Uncaria tomentosa (cat's claw) extracts, fractions on normal and cancer cells: a systematic review.. Frontiers in pharmacology. DOI PubMed
  5. Meta-analysisArado GM, Amatto PPG, Marins M, Rizzi ES, et al. (2024). Anti-inflammatory and/or immunomodulatory activities of Uncaria tomentosa (cat's claw) extracts: A systematic review and meta-analysis of in vivo studies.. Frontiers in pharmacology. DOI PubMed
  6. ReviewRosenbaum CC, O'Mathúna DP, Chavez M, Shields K (2010). Antioxidants and antiinflammatory dietary supplements for osteoarthritis and rheumatoid arthritis.. Alternative therapies in health and medicine. PubMed
  7. Kaziulin AN, Petukhov AB, Kucheriavyĭ IuA (2006). [Efficiency of includes of bioactive substances in diet of patient with hepatic encephalopathy].. Voprosy pitaniia. PubMed
Show 2 more references
  1. Miller MJ, Mehta K, Kunte S, Raut V, et al. (2005). Early relief of osteoarthritis symptoms with a natural mineral supplement and a herbomineral combination: a randomized controlled trial [ISRCTN38432711].. Journal of inflammation (London, England). DOI PubMed
  2. Lamm S, Sheng Y, Pero RW (2001). Persistent response to pneumococcal vaccine in individuals supplemented with a novel water soluble extract of Uncaria tomentosa, C-Med-100.. Phytomedicine : international journal of phytotherapy and phytopharmacology. DOI PubMed