Herb library · Herb · Uncaria tomentosa, Uncaria guianensis
Cat's claw
A woody Amazon vine sold for arthritis, viral infections and cancer. There is no conclusive evidence from studies in people that it helps with any health purpose.
Traditional use
Cat's claw grows wild in the Amazon rainforest and other tropical parts of Central and South America, where Indigenous people have used it for centuries to ward off illness. Most US products contain U. tomentosa. Today it is promoted for osteoarthritis, rheumatoid arthritis, cancer, viral infections and other conditions.
What studies show
- Insufficient
Arthritis, viral infections (including COVID-19) and other uses: there is no conclusive evidence from studies in people. Very few high-quality trials exist, and many studies were too small or not rigorous enough to reach conclusions.
Be careful of
Cautions
- NoteIt appears safe by mouth for short periods, up to about 6 months; too little is known about using it on the skin.
- ConditionIt might make the immune system more active, which could worsen autoimmune diseases. It may also slow blood clotting, which might raise bleeding risk during surgery; tell your clinician if you have surgery scheduled.
- InteractionThere are theoretical reasons to expect interactions with blood thinners (anticoagulant and antiplatelet drugs), blood pressure drugs, and other supplements.
- PregnancySome studies suggest it is unsafe during pregnancy. Little is known about breastfeeding.
- Ask a clinicianTalk with a clinician or pharmacist before using this if you take prescription medicines, are pregnant or breastfeeding, or are giving it to a child.
Sources
- Cat's Claw: Usefulness and Safety (opens in a new tab) · NCCIH · read September 25, 2026
Reviewed September 25, 2026.