Myth or fact

Creatine damages your kidneys

Short answerNot the way you think

By GyroscopeUpdated November 14, 20269 sources

Not in healthy people. Creatine raises creatinine, the waste product a standard kidney test uses, by about 0.14 mg/dL on average. That makes the kidney score worked out from creatinine look lower. But across 26 trials, kidney filtering measured directly didn’t drop. If you already have kidney disease, ask your doctor before you take it.

Why people believe it

Because the number your doctor looks at goes up. Creatinine is the main kidney marker on a standard blood test, and creatine raises it. Anyone who sees “creatinine high” next to “takes creatine” can draw a straight line between them.

The fear also has a starting date. In 1998, doctors published a case about a young man who had had kidney disease for 8 years and had been on an immune-suppressing drug for 5. He started creatine, 15 g a day for a week and then 2 g a day, and his creatinine went up, so his doctors presumed his kidneys were getting worse. He stopped the creatine. A 2021 review notes that the case report ignored two things already known at the time, that creatine raises creatinine without harming the kidneys, and that his daily dose after the first week was about what a big steak carries. Two teams of creatine researchers wrote to the journal to say so, but the idea had already spread.

It’s like a line at a toll booth

Picture a toll booth that works at the same speed all day. Send more cars and the line gets longer, even though the booth is working just as fast. A creatinine test counts the line. Creatine sends more cars, because more stored creatine means more creatinine made each day. The booth, your kidneys, keeps working the same.

Why creatine raises creatinine

About 1 to 2% of the creatine in your muscles breaks down every day into creatinine, which your kidneys clear into urine. Fill your muscles with more creatine and you make more creatinine, so there’s a little more in your blood at any moment.

Your kidney score, the eGFR, is usually worked out from creatinine, your age and your sex, and it assumes an average amount of muscle making an average amount of creatinine. Give it a higher creatinine and it prints a lower score. It has no way to know the extra came from a scoop. People with a lot of muscle run into the same problem without any supplements.

What the trials found

The three numbers from the big review show the whole story in one look.

What about cystatin C?

Cystatin C is a small protein your body makes at a steady rate, cleared by the kidneys like creatinine but without the link to muscle. In a 2008 study of 170 healthy adults, creatinine tracked lean mass and cystatin C didn’t. The National Kidney Foundation says a cystatin C test can help when creatinine may mislead, including in people with a lot of muscle, though it may not be accurate with an untreated thyroid problem or on steroids. The creatinine check shows how your result compares with the rise creatine usually causes.

The best case for worry

There are a few case reports of kidney trouble in people taking creatine. In 2025, doctors described a 17-year-old who developed kidney injury after a six-day high-dose loading regimen, with both creatinine and cystatin C rising. A single case can’t show that creatine caused it. But it’s a fair reason why teenagers shouldn’t take creatine, especially in big loading doses, and why we don’t give a dose under 18.

For people who already have kidney disease, the trials are fewer. The International Society of Sports Nutrition notes that some experts suggest they check with their doctor first, out of caution, and we agree. Creatine changes one of the numbers their doctor uses to track their kidneys.

How long has this been tested?

Long enough to be reassuring. Creatine became a popular supplement in the early 1990s, and more than 1,000 studies have followed. Studies of patients have used up to 30 g a day for as long as five years. A 2021 review points out that if creatine harmed healthy kidneys, nearly 30 years of wide use would have turned up a rise in kidney damage among young, fit people, and it hasn’t.