None of the clinical trials that have studied the effects of Tribulus terrestris have reported an increase in adverse side effects when compared to placebo treatments.[1][2][3] While no toxicology studies have been conducted in humans, rodent studies that have administered Tribulus terrestris at a dose of 500 mg per kilogram of body weight (mg/kg) for 28 days (equivalent to a human dose of 80 mg/kg after adjusting for metabolic and size differences) didn’t observe any toxic side effects.[4] In vitro studies have shown cytotoxic, genotoxic, and endocrine-disrupting effects of Tribulus terrestris, but it is unknown how this may translate to humans.[5]