Medically reviewed on Jun 7, 2018
What is Cat's Claw?
Cat's claw is a tropical vine of the madder family (Rubiaceae). The name describes the small, curved-back spines on the stem at the leaf juncture, which resemble claws. U. tomentosa and U. guianensis are found in South America and are known in Peru as uña de gato (Spanish for cat's claw). Large amounts of U. guianensis are collected in South America for the European market, while American sources prefer U. tomentosa.
Uncaria tomentosa (Willd.) DC and Uncaria guianensis (Aubl.) Gmel.
Cat's claw, Cortex Uncariae, life-giving vine of Peru, samento, uña de gato, and various commercial preparations, including C-Med 100 and Reparagen.
- C-Med 100
What is it used for?
Cat's claw has a history of folklore use in South America for wound healing and for treating arthritis, stomach ulcers, intestinal disorders, and some skin disorders and tumors. The part used medicinally is the inner bark of the vine or root. In Peru, a boiled water extract of U. guianensis is used for inflammation, arthritis, and contraception, as well as for treating stomach ulcers and tumors, gonorrhea (by the Bora tribe), diarrhea (by the Indian populations of Colombia and Guiana), and cancers of the urinary tract in women. The Ashanica Indians believe that samento (U. tomentosa) has life-giving properties and ingest a cup of the extracts every 1 to 2 weeks to ward off disease, treat bone pain, and cleanse the kidneys. Other reported uses include treatment for abscesses, asthma, chemotherapy adverse effects, fever, bleeding, rheumatism, skin impurities, urinary tract inflammation, weakness, and wounds, as well as for disease prevention and recovery from childbirth.
Demand for the bark has been partially attributed to European clinical use with zidovudine in AIDS treatment. The demand for the bark in the United States is based on its purported use as a tea in treating diverticulitis, hemorrhoids, peptic ulcers, colitis, gastritis, parasites, and "leaky gut syndrome." There are, however, no controlled clinical trials to support these uses.
Despite multiple purported effects, controlled clinical trials are lacking. Suggested anti-inflammatory, anticancer, and immune system stimulant properties are largely based on in vitro and limited animal studies.
What is the recommended dosage?
One gram of root bark given 2 to 3 times daily is a typical dose, while 20 to 30 mg of a root bark extract has been recommended. Clinical trials are generally lacking to support appropriate dosages. A standardized extract containing 8% to 10% carboxy alkyl esters and less than 0.5% oxindole alkaloids has been used in clinical studies in doses of 250 to 300 mg.
Cat's claw products should be avoided before and after surgery, as well as by those using immunosuppressant therapy and in children due to lack of safety data.
Information regarding safety and efficacy during pregnancy and lactation is lacking.
Case reports are generally lacking; however, there is a reported interaction with HIV protease inhibitors.
Although reports of adverse effects are rare, GI complaints (nausea, diarrhea, stomach discomfort), kidney effects, nervous system disorders, and an increased risk of bleeding with anticoagulant therapy are possible.
Historical evidence and current use by consumers suggest low toxicity; however, toxicological studies are limited.