Firstly, do you need creatine? Well then, as long as you stick 
to the suggested dose of creatine, your waste-filtration system is safe. Kidney malfunction raises creatinine (a by-product of creatine), but high creatinine doesn’t damage kidneys, says Dr Gordon Purser, a chemist at the University of Tulsa. However, if you have kidney disease (or any exisiting kidney ailment) you should not be using creatine, says Dr Amanda Claasen, registered dietician and exercise scientist at the South African Institute for Drug Free Sport (SAIDS).