The consumption of oral creatine monohydrate is popular among professional and amateur athletes, but there is limited information on its possible adverse effects. This review aims to present scientific facts and contrast them with media reports that often emphasize the health risks of creatine supplementation based on individual cases.
Athletes typically consume up to 20 g/day of creatine for a few days, followed by lower doses for extended periods. Adverse effects are rarely reported, but there are anecdotal claims of gastrointestinal disturbances and muscle cramps. Some studies suggest protective effects of creatine in heart, muscle, and neurological diseases. Liver and kidney dysfunction have been suggested, but well-controlled studies on adverse effects are scarce.
A study on young athletes showed no evidence of liver dysfunction during four weeks of creatine supplementation. Other studies monitored kidney function in athletes using clearance methods and urine protein excretion rate and found no adverse effects. The review does not draw conclusions on the impact of creatine on sports performance but suggests that there is no evidence of harmful effects in healthy individuals.
However, large amounts of an exogenous substance containing an amino group may impose a burden on the liver and kidneys, leading to idiosyncratic effects. Regular monitoring is essential to prevent abnormal reactions during creatine supplementation.