Some randomized controlled trials report headaches, sleep problems, and flatulence in people receiving African mango supplements.[1][2] However, similar symptoms are also reported by people randomized to receive placebo,[1][2] so African mango supplements are unlikely a direct cause of these side effects.
There is one reported case of renal failure associated with African mango consumption in a person with chronic kidney disease,[3] but causality cannot be certain. Rodent experiments do not find evidence of toxicity caused by extracts of African mango seeds.[4] However, there are currently no pharmacological or toxicology studies that have involved humans. Such studies are needed to fully understand the safety of African mango supplements.