Cat's claw (Uncaria tomentosa) is a woody vine native to the Amazon rainforest and other tropical areas of South and Central America. It is named after the hook-like thorns that grow along its vine. The bark and root of this herb have been used by South Americans going back to the Inca civilization to treat a variety of health problems including arthritis, stomach ulcers, inflammation, dysentery, and fevers. It was also used as a form of birth control.

Test tube studies indicate that cat's claw may stimulate the immune system, help relax the smooth muscles (such as the intestines), dilate blood vessels (helping lower blood pressure), and act as a diuretic (helping rid the body of excess water). It also has antioxidant properties, helping rid the body of particles known as free radicals that damage cells.

Osteoarthritis

Although few scientific studies have investigated the safety and usefulness of this herb, it has been used traditionally to treat osteoarthritis (OA). One study indicates that it may help relieve pain from knee OA without side effects.

Rheumatoid arthritis

Cat's claw has been suggested as a treatment for rheumatoid arthritis (RA) based on its anti-inflammatory properties. One small study showed a positive effect when cat's claw was taken by people who were also taking sulfasalazine or hydroxychloroquine to treat RA. Although cat's claw may help reduce inflammation, there is no evidence it stops the progression of the disease. For that reason, RA should be treated with conventional medications, which can put the disease into remission.

Further research

Cat's claw is being studied for a number of other possible uses, although it is too early to say whether it will be effective. Among the conditions cat's claw is being studied for are HIV, Crohn's disease, multiple sclerosis, systemic lupus erythematosus (SLE or lupus), and Alzheimer's disease.

Cat's claw is a thorny vine that can climb as high as 100 feet. It is primarily found in the Amazon rainforest as well as tropical areas in South and Central America. Much of the cat's claw sold in the United States was grown in Peru.

Cat's claw got its name from the curved, claw-like thorns that grow on its stem. The root and bark of cat's claw are the parts used for medicinal purposes.

Cat's claw contains many types of plant chemicals that help reduce inflammation (such as tannins and sterols) and combat certain viruses (such as quinovic acid glycosides).

Cat's claw preparations are made from the root and bark of the cat's claw vine. The effectiveness of the root and bark can vary depending upon what time of year that portion of the plant is harvested.

The bark of the cat's claw vine can be crushed and used to make tea. Standardized root and bark extracts (containing 3% alkaloids and 15% phenols) are also available in either liquid or capsule forms.

Pediatric

There are no known scientific reports on the pediatric use of cat's claw. Do not give a child cat's claw without the supervision of your doctor.

Adult

• Tea: 1 to 10 g (1,000 mg) root bark in 8 ounces water; boil 10 to 15 minutes, cool, and strain. Drink 1 cup three times daily.
• Tincture (solution made from herb and alcohol, or herb, alcohol, and water): 1/4 to 1/2 teaspoonful two to three times daily
• Dry, encapsulated standardized extract: 100 mg per day for osteoarthritis; 250 to 350 mg per day for immune support

The use of herbs is a time-honored approach to strengthening the body and treating disease. Herbs, however, can trigger side effects and can interact with other herbs, supplements, or medications. For these reasons, herbs should be taken with care, under the supervision of a health care practitioner.

Cat's claw appears to have few side effects. However, there have not been enough scientific studies of cat's claw to fully determine its safety. Some people have reported dizziness, nausea, and diarrhea when taking cat's claw. The diarrhea or loose stools tend to be mild and go away with continued use of the herb.

Cat's claw may cause miscarriage and should not be taken by pregnant or nursing women. Because of its possible effects on the immune system, it should not be used by individuals with autoimmune diseases, skin grafts, tuberculosis, or by those receiving organ transplants.

If you are currently being treated with any of the following medications, you should not use cat's claw without first talking to your health care provider.

Immunosuppressive medications -- In theory, because cat's claw may stimulate the immune system, it should not be used with medications intended to suppress the immune system, such as cyclosporin or other medications prescribed following an organ transplant or to treat an autoimmune disease.

NSAIDs -- Cat's claw may protect against gastrointestinal damage associated with nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil, Motrin) and naproxen (Aleve).

Other medications -- Cat's claw may interact with the following medications:

• Anticoagulants (blood-thinning medication)
• Diuretics (water pills)
• Estrogens or progestins, including birth control pills
• Antihypertensive (blood pressure) medication

Aquino R, De Feo V, De Simone F, et al. New compounds and anti-inflammatory activity of Uncaria tomentosa. J Nat Prod. 1991;54: 453-459.

Foster S, Tyler VE. Tyler's Honest Herbal. 4th ed. New York: The Haworth Herbal Press; 1999: 97-99.

Hardin SR. Cat's claw: an Amazonian vine decreases inflammation in osteoarthritis. Complement Ther Clin Pract. 2007 Feb;13(1):25-8.

Karch SB. The Consumer's Guide to Herbal Medicine. Hauppauge, New York: Advanced Research Press; 1999:55-56.

Keplinger K, Laus G, Wurm M, et al. Uncaria tomentosa (Willd.) DC—ethnomedicinal use and new pharmacological, toxicological and botanical results. J Ethnopharmacol. 1999;64:23–34.

Lemaire I, Assinewe V, Cano P, et al. Stimulation of interleukin-1 and -6 production in alveolar macrophages by the neotropical liana, Uncaria tomentosa. J Ethnopharmacol. 1999;64:109–115.

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. 2002 Apr;29(4):678-81.

Pilarski R, Zielinski H, Ciesiolka D, et al. Antioxidant activity of ethanolic and aqueous extracts of Uncaria tomentosa (Willd.) DC. J Ethnopharmacol. 2006 Mar 8;104(1-2):18-23.

Piscoya J, Rodriguez Z, Bustamante SA, et al. Efficacy and safety of freeze-dried cat's claw in osteoarthritis of the knee: mechanisms of action of the species Uncaria guianensis. Inflamm Res. 2001;50(9):442-448.

Rizzi R, Re F, Bianchi A, et al. Mutagenic and antimutagenic activities of Uncaria tomentosa and its extracts. J Ethnopharmacol. 1993;38(1):63-77.

Rotblatt M, Ziment I. Evidence-Based Herbal Medicine. Philadelphia, PA: Hanley & Belfus, Inc; 2002:114-118.

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. 2000;29(1):71-78.

Setty AR, Sigal LH. Herbal medications commonly used in the practice of rheumatology: mechanisms of action, efficacy, and side effects. Semin Arthritis Rheum. 2005 Jun;34(6):773-84. Review.

Sheng Y, et al. Induction of apoptosis and inhibition of proliferation in human tumor cells treated with extracts of Uncaria tomentosa. Anticancer Res. 1998;18:3,363–3,368.

Sheng Y, Pero RW, Wagner H. Treatment of chemotherapy-induced leukopenia in a rat model with aqueous extract from Uncaria tomentosa. Phytomedicine. 2000;7(2):137-143.

Spelman K, Burns J, Nichols D, et al. Modulation of cytokine expression by traditional medicines: a review of herbal immunomodulators. Altern Med Rev. 2006 Jun;11(2):128-50. Review.

Steinberg PN. Cat's claw: medicinal properties of this Amazon vine. Nutrition Science News. 1995.