Cat's Claw

Purported Benefits, Side Effects & More

Cat's Claw

Purported Benefits, Side Effects & More
Cat's Claw

Common Names

  • Una de gato
  • Saventaro
  • Life-giving vine of Peru
  • Hawk's claw

For Patients & Caregivers

Tell your healthcare providers about any dietary supplements you’re taking, such as herbs, vitamins, minerals, and natural or home remedies. This will help them manage your care and keep you safe.

What is it?

Cat's claw has not been shown to be effective for cancer or AIDS.

Cat's claw is a vine native to South America, the bark of which has been used in traditional medicine to treat various conditions such as gastric and inflammatory disorders. It is marketed as a dietary supplement to support the body's natural defenses, for digestive and joint health, and as a general health tonic.

In lab experiments, compounds from cat's claw stimulated specific immune cells known as phagocytes and T-helper cells. Other lab studies suggest cat’s claw may enhance DNA repair, or reduce inflammation and some chemotherapy side effects. However, one lab study showed it may actually stimulate pediatric leukemia cells.

Data in humans are limited, and studies on safety and effectiveness for any condition are needed.

What are the potential uses and benefits?
  • To treat arthritis

    A small study of a highly purified extract suggested modest benefit in patients with active rheumatoid arthritis, but larger well-designed studies are needed.
  • To reduce chemotherapy side effects

    Small studies suggest cat's claw may protect against abnormally low white blood cell counts in patients receiving certain cancer treatments. It may also improve quality of life in those with advanced cancer. However, additional studies are needed.
  • To treat cancer

    Lab studies suggest cat's claw might inhibit certain cancer cells, although one study suggests it may also stimulate pediatric leukemia cells. Human data are lacking.
  • To treat gastrointestinal disorders

    Lab studies suggest cat's claw may reduce inflammation, but this has not been studied in humans.
  • To treat HIV and AIDS

    Lab studies suggest cat's claw can stimulate specific immune cells, but human studies are needed.
What are the side effects?
  • Nausea, diarrhea, stomach discomfort

Case reports

  • Kidney failure in a patient with lupus
  • Worsening movement in a patient with Parkinson’s disease
What else do I need to know?

Do Not Take if:

  • You are taking warfarin or other blood thinners: Cat's claw may increase bruising and bleeding risk. Clinical relevance is not known.
  • You are taking antiretroviral drugs: Case reports have shown that cat's claw increases serum concentrations of atazanavir, ritonavir, and saquinavir, and can therefore increase their side effects.
  • You are taking CYP 3A4 or 2J2 substrate drugs: Cat's claw may alter the effect of drugs metabolized by these enzymes. Clinical relevance is not known.
  • You are taking UGT 1A3 or 1A9 substrate drugs: Cat's claw may alter the effect of drugs metabolized by these enzymes. Clinical relevance is not known.

For Healthcare Professionals

Scientific Name
Uncaria tomentosa
Clinical Summary

Cat’s claw is a vine native to South America, the bark of which has been used in traditional medicine to treat various conditions such as gastric and inflammatory disorders (1). It is marketed as a dietary supplement to support the body’s natural defenses, for digestive and joint health, and as a general health tonic.

In vitro studies suggest some of the plant constituents have antiviral, antimutagenic, anti-inflammatory, and immunomodulatory properties, and may enhance phagocytosis (1) (2) (3) (4) (5) (6). Anticancer effects have also been observed (8) (9) (10) (11) (12), and bioassays suggest cat’s claw may increase neutrophil count (13).

Data in humans are limited. Small studies suggest cat’s claw may be helpful for active rheumatoid arthritis (14) and denture stomatitis (31). It also reduced chemotherapy adverse effects in a study of breast cancer patients (15), and improved quality of life in patients with advanced cancer (32). However preclinical data of a cat’s claw extract showed it could stimulate survival of pediatric leukemic cells (16). Therefore, larger studies evaluating safety and efficacy are needed.

Purported Uses and Benefits
  • AIDS
  • Arthritis
  • Cancer
  • Chemotherapy side effects
  • GI disorders
Mechanism of Action

Oxindole alkaloids in cat’s claw have immunostimulating properties in vitro, increasing phagocytotic activity and synthesis of WBCs (5) and enhancing T-helper cell function (2). Inhibition of TNFα production (3) (4) has been linked to observed anti-inflammatory activities. Mitraphylline isolated from cat’s claw was also identified as possessing anti-inflammatory effects by inhibiting release of IL1α, 1β, 4, 17, and TNFα (21).

In other preclinical studies, aqueous extracts enhanced DNA repair after chemically-induced damage (22). Protection against oxidative DNA damage following UVB exposure may occur via enhanced base excision repair and inherent antioxidant effects (23). The biphasic manner in which cat’s claw modulates anxiety, initially inducing and then reversing the effect after long-term administration, is attributed to the presence of alkaloids and flavonols (18).

The quinovic acid glycoside purified fraction of cat’s claw inhibited human bladder cancer cells via NF-κB modulation to induce apoptosis (20). Cat’s claw also inhibited lactate dehydrogenase-A, an enzyme highly expressed in malignant and treatment-resistant tumors with poor clinical outcomes (24). In vivo studies demonstrated antineoplastic effects against breast tumors due to modulation of oxidative stress and synergy among constituents with antioxidant properties, rather than alkaloid activity (12).

Adverse Reactions

GI complaints: Nausea, diarrhea, stomach discomfort (25)

Case reports
Acute renal failure: In a patient with systemic lupus erythematosus (26).
Worsening motor signs: In a 38-year-old patient with Parkinson’s disease following oral intake of cat’s claw extract (27).

Herb-Drug Interactions

Anticoagulants, antihypertensives: May increase effects of cardiovascular drugs, including increased bleeding risk (25) (28). Clinical relevance is not known.

Antiretrovirals: Cat’s claw increased serum concentrations of atazanavir, ritonavir, and saquinavirn in an AIDS patient (30). Data from 28 pharmacokinetic studies and case series/reports also indicate that cat’s claw significantly increases levels of antiretrovirals (34).

CYP450 substrates: In vitro, cat’s claw inhibits CYP3A4 and may increase the serum levels of drugs such as nonnucleoside reverse-transcriptase inhibitors, cyclosporine, and some benzodiazepines (29). Other data suggest a cat’s claw extract could induce 2J2 (33). Clinical relevance is not known.

UGT substrates: A cat’s claw extract induced UGT1A3 and 1A9 and may alter the effect of drugs metabolized by these enzymes (33). Clinical relevance is not known.

Dosage (OneMSK Only)
  1. Reis SR, Valente LM, Sampaio AL, et al. Immunomodulating and antiviral activities of Uncaria tomentosa on human monocytes infected with Dengue Virus-2. Int Immunopharmacol. Mar 2008;8(3):468-476.
  2. Riva L, Coradini D, Di Fronzo G, et al. The antiproliferative effects of Uncaria tomentosa extracts and fractions on the growth of breast cancer cell line. Anticancer Res. Jul-Aug 2001;21(4A):2457-2461.
  3. Sandoval M, Charbonnet RM, Okuhama NN, et al. Cat’s claw inhibits TNFalpha production and scavenges free radicals: role in cytoprotection. Free Radic Biol Med. Jul 1 2000;29(1):71-78.
  4. Sandoval M, Okuhama NN, Zhang XJ, et al. Anti-inflammatory and antioxidant activities of cat’s claw (Uncaria tomentosa and Uncaria guianensis) are independent of their alkaloid content. Phytomedicine. May 2002;9(4):325-337.
  5. Sheng Y, Bryngelsson C, Pero RW. Enhanced DNA repair, immune function and reduced toxicity of C-MED-100, a novel aqueous extract from Uncaria tomentosa. J Ethnopharmacol. Feb 2000;69(2):115-126.
  6. Caon T, Kaiser S, Feltrin C, et al. Antimutagenic and antiherpetic activities of different preparations from Uncaria tomentosa (cat’s claw). Food Chem Toxicol. Apr 2014;66:30-35.
  7. Mammone T, Akesson C, Gan D, et al. A water soluble extract from Uncaria tomentosa (Cat’s Claw) is a potent enhancer of DNA repair in primary organ cultures of human skin. Phytother Res. Mar 2006;20(3):178-183.
  8. Garcia Prado E, Garcia Gimenez MD, De la Puerta Vazquez R, et al. Antiproliferative effects of mitraphylline, a pentacyclic oxindole alkaloid of Uncaria tomentosa on human glioma and neuroblastoma cell lines. Phytomedicine. Apr 2007;14(4):280-284.
  9. Pilarski R, Poczekaj-Kostrzewska M, Ciesiolka D, et al. Antiproliferative activity of various Uncaria tomentosa preparations on HL-60 promyelocytic leukemia cells. Pharmacol Rep. Sep-Oct 2007;59(5):565-572.
  10. Rinner B, Li ZX, Haas H, et al. Antiproliferative and pro-apoptotic effects of Uncaria tomentosa in human medullary thyroid carcinoma cells. Anticancer Res. Nov 2009;29(11):4519-4528.
  11. Garcia Gimenez D, Garcia Prado E, Saenz Rodriguez T, et al. Cytotoxic effect of the pentacyclic oxindole alkaloid mitraphylline isolated from Uncaria tomentosa bark on human Ewing’s sarcoma and breast cancer cell lines. Planta Med. Feb 2010;76(2):133-136.
  12. Dreifuss AA, Bastos-Pereira AL, Fabossi IA, et al. Uncaria tomentosa exerts extensive anti-neoplastic effects against the Walker-256 tumour by modulating oxidative stress and not by alkaloid activity. PLoS One. 2013;8(2):e54618.
  13. Farias I, do Carmo Araujo M, Zimmermann ES, et al. Uncaria tomentosa stimulates the proliferation of myeloid progenitor cells. J Ethnopharmacol. Sep 1 2011;137(1):856-863.
  14. Mur E, Hartig F, Eibl G, et al. Randomized double blind trial of an extract from the pentacyclic alkaloid-chemotype of Uncaria tomentosa for the treatment of rheumatoid arthritis. J Rheumatol. Apr 2002;29(4):678-681.
  15. Santos Araujo Mdo C, Farias IL, Gutierres J, et al. Uncaria tomentosa-adjuvant treatment for breast cancer: clinical trial. Evid Based Complement Alternat Med. 2012;2012:676984.
  16. Styczynski J, Wysocki M. Alternative medicine remedies might stimulate viability of leukemic cells. Pediatr Blood Cancer. Jan 2006;46(1):94-98.
  17. Hemingway SR, Phillipson JD. Proceedings: Alkaloids from S. American species of Uncaria (Rubiaceae). J Pharm Pharmacol. Dec 1974;26 Suppl:113P.
  18. Bigliani MC, Rosso MC, Zunino PM, et al. Anxiogenic-like effects of Uncaria tomentosa (Willd.) DC. aqueous extract in an elevated plus maze test in mice: a preliminary study. Nat Prod Res. 2013;27(18):1682-1685.
  19. Kaiser S, Dietrich F, de Resende PE, et al. Cat’s claw oxindole alkaloid isomerization induced by cell incubation and cytotoxic activity against T24 and RT4 human bladder cancer cell lines. Planta Med. Oct 2013;79(15):1413-1420.
  20. Dietrich F, Kaiser S, Rockenbach L, et al. Quinovic acid glycosides purified fraction from Uncaria tomentosa induces cell death by apoptosis in the T24 human bladder cancer cell line. Food Chem Toxicol. May 2014;67:222-229.
  21. Rojas-Duran R, Gonzalez-Aspajo G, Ruiz-Martel C, et al. Anti-inflammatory activity of Mitraphylline isolated from Uncaria tomentosa bark. J Ethnopharmacol. Oct 11 2012;143(3):801-804.
  22. Sheng Y, Li L, Holmgren K, et al. DNA repair enhancement of aqueous extracts of Uncaria tomentosa in a human volunteer study. Phytomedicine. Jul 2001;8(4):275-282.
  23. Emanuel P, Scheinfeld N. A review of DNA repair and possible DNA-repair adjuvants and selected natural anti-oxidants. Dermatol Online J. 2007;13(3):10.
  24. Deiab S, Mazzio E, Messeha S, et al. High-Throughput Screening to Identify Plant Derived Human LDH-A Inhibitors. European J Med Plants. 2013;3(4):603-615.
  25. Erowele GI, Kalejaiye AO. Pharmacology and therapeutic uses of cat’s claw. Am J Health Syst Pharm. Jun 1 2009;66(11):992-995.
  26. Hilepo JN, Bellucci AG, Mossey RT. Acute renal failure caused by ’cat’s claw’ herbal remedy in a patient with systemic lupus erythematosus. Nephron. 1997;77(3):361.
  27. Cosentino C, Torres L. Reversible worsening of Parkinson disease motor symptoms after oral intake of Uncaria tomentosa (cat’s claw). Clin Neuropharmacol. Sep-Oct 2008;31(5):293-294.
  28. Vogel JH, Bolling SF, Costello RB, et al. Integrating complementary medicine into cardiovascular medicine. A report of the American College of Cardiology Foundation Task Force on Clinical Expert Consensus Documents (Writing Committee to Develop an Expert Consensus Document on Complementary and Integrative Medicine). J Am Coll Cardiol. Jul 5 2005;46(1):184-221.
  29. Scott GN, Elmer GW. Update on natural product—drug interactions. Am J Health Syst Pharm. Feb 15 2002;59(4):339-347.
  30. Lopez Galera RM, Ribera Pascuet E, Esteban Mur JI, et al. Interaction between cat’s claw and protease inhibitors atazanavir, ritonavir and saquinavir. Eur J Clin Pharmacol. Dec 2008;64(12):1235-1236.
  31. Tay LY, Jorge JH, Herrera DR, et al. Evaluation of different treatment methods against denture stomatitis: a randomized clinical study. Oral Surg Oral Med Oral Pathol Oral Radiol. 2014 Jul;118(1):72-7.
  32. de Paula LC, Fonseca F, Perazzo F, et al. Uncaria tomentosa (cat’s claw) improves quality of life in patients with advanced solid tumors.J Altern Complement Med. 2015 Jan;21(1):22-30.
  33. Weiss J. Herb⁻Drug Interaction Potential of Anti-Borreliae Effective Extracts from Uncaria tomentosa (Samento) and Otoba parvifolia (Banderol) Assessed In Vitro. Molecules. 2018 Dec 31;24(1). pii: E137.
  34. Jalloh MA, Gregory PJ, Hein D, Risoldi Cochrane Z, Rodriguez A. Dietary supplement interactions with antiretrovirals: a systematic review. Int J STD AIDS. 2017 Jan;28(1):4-15.
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