No life threatening side effects or toxicity concerns were observed during the human trials when using the upper range dose of 25mg per day. However, a few “adverse events” were observed by researchers during the various trials. The most common ones associated with Kanna supplementation included loss of appetite, headaches, abdominal pain, and upper respiratory tract infections.
Lastly, no toxicological concerns were observed in rats when given doses of 5,000mg/kg body weight, roughly 1,800x greater than the recommended human intake, for over two weeks. Now, rat physiology is vastly different from that of humans, but this is just to drive the point home that the 25mg dose you may consume per day shouldn’t pose any immediate life-threatening consequences.