Cat's claw is a woody climbing plant native to the Amazon rainforest that grows throughout the tropical jungles of Central and South America. There are two species of this plant, both of which have certain medicinal uses. Uncaria guianensis may be useful for treating osteoarthritis, while Uncaria tomentosa has a long history of native medicinal use and is currently undergoing research to determine its pharmaceutical properties. Cat's claw supplements are made from the root and inner bark and may take the form of capsules, tea, or tincture.
U. tomentosa has been used by the Asháninka tribe of Peru for over 2,000 years to treat such diverse complaints as acne, cancer, diabetes, diarrhea, gastrointestinal inflammation, and urinary tract diseases. Indigenous people also used cat's claw as a contraceptive and to promote general health. In homeopathic medicine, this plant is used to address a number of gastrointestinal complaints. It has also been used to treat AIDS, arthritis, chronic fatigue syndrome, diabetes, immune disorders, lupus, Lyme disease, premenstrual syndrome, and prostate conditions.
Recent research on cat's claw has focused on its use as a treatment for cancer, HIV, and other immune disorders. There are two distinct chemotypes of U. tomentosa, each of which contains a different type of alkaloids. One chemotype is useful for strengthening the immune system, while the other inhibits the positive effects of the first type and can even be dangerous.
This second chemotype of cat's claw makes the heart beat more weakly and slowly and can lead to ataxia and lethargy. It is impossible to distinguish between the two chemotypes visually, so cat's claw collected from the wild may be of either type, making pharmacological research difficult. Cat's claw of either chemotype can also trigger allergic reaction, manifesting in a rash, itchiness, or, in the extreme, inflammation of the kidneys. A cat's claw allergy may be quite serious for patients with compromised kidneys.