When taken by mouth, cat's claw may cause headaches, dizziness, and vomiting.
Studies show that cat's claw isn't toxic at standard dosing levels. At higher doses, it may be toxic.
If you are pregnant or breastfeeding, you should not use cat's claw.
Cat's claw may interact with some HIV and AIDS medicines.
Because cat's claw may stimulate the immune system, people with certain autoimmune conditions shouldn't use it. These include people with an overactive immune system. Cat's claw may also affect blood pressure and blood clotting.