According to test tube studies, oxyindole alkaloids in cat’s claw stimulate immune function.² Alkaloids and glycosides in cat’s claw have also demonstrated anti-inflammatory and antioxidant activity.^{3, 4}

Although clinical trials are lacking, cat’s claw has become very popular in North America and is sometimes recommended for people with cancer or HIV infection. A cigarette smoker who took a freeze-dried extract of cat’s claw root bark for one month showed a sharp decrease in one urinary cancer marker.⁵ This finding, however, does little to support the use of the herb in persons with cancer and points toward the need for actual clinical studies to determine its effectiveness.

Cat’s claw has been used traditionally for osteoarthritis and rheumatoid arthritis. Double-blind trials have confirmed the effectiveness of cat's claw for each of these conditions.⁶⁷