Does creatine put a strain on your kidneys?

Creatine supplements slightly raise your blood creatinine levels. That may sound alarming, but it is a well-known side effect: creatine is spontaneously converted in the body into creatinine, causing the value on a blood test to come out a little higher. It is not a sign that your kidneys are functioning less well, but it can mislead doctors when they interpret your blood result without knowing you are taking creatine.

Actual kidney function remains normal. The filtration rate of the kidneys, a more reliable measure than creatinine, does not change significantly with creatine use. Plasma urea, another waste product that indicates how hard the kidneys are working, also remains stable. Multiple systematic reviews and meta-analyses in healthy individuals find no deterioration in kidney function at the recommended dose of 3 to 5 grams per day.

Isolated cases of kidney and liver problems have been reported, but these involved people who combined creatine with other supplements or used clearly higher doses over longer periods. Those cases do not come from controlled studies and say little about the standard user who sticks to the guidelines.

Do you have an existing kidney condition, or are you taking medications that can put strain on the kidneys? In that case, there is simply not enough controlled research to say that creatine is safe for you. Discuss it with your doctor first, even though people with healthy kidneys have been using it for years without any demonstrable problem.