Is creatine safe?

What the research actually tested

Most performance studies use creatine monohydrate and measure short-term power, repeated efforts, strength or training adaptation. They do not establish that expensive alternative forms are superior or that creatine improves endurance performance.1

Why the scale can change

An early increase in body mass can reflect water stored with muscle creatine rather than new muscle tissue. That distinction matters when a product is marketed for weight change or body composition.1

Why creatinine and kidney function are not the same

Creatinine is a waste product that clinicians use to help estimate how well the kidneys filter blood. Some creatine is converted to creatinine, so taking creatine can raise the blood result and change a creatinine-based estimate of filtration without necessarily indicating kidney injury. But a changed result should not automatically be dismissed as the supplement: kidney problems have other causes. Tell the clinician or laboratory about creatine and other supplements when discussing blood tests; let a clinician interpret the result in context.

If the result is difficult to interpret, a clinician may consider another blood marker, cystatin C, and a urine albumin test, depending on the situation. Cystatin C can be used to estimate filtration, while urine albumin looks for protein leakage that may indicate kidney damage; they answer related but different questions. NIDDK notes that estimates combining creatinine and cystatin C are often more accurate, but every estimate has limitations. These tests are not automatic proof that a specific supplement is safe or that the kidneys are healthy; the appropriate assessment depends on the person and the reason for testing.356

What studies measured—and what remains uncertain

A 2026 review combined 26 trials involving 1,036 participants; only four trials lasted more than six months. The results for blood creatinine varied substantially between studies, so the average cannot predict an individual result. On average, creatinine rose and creatinine-based filtration estimates fell; results using a different filtration measurement did not show a statistically significant difference. That is not proof that harm is impossible. In one 2013 trial, 26 apparently healthy resistance-trained adults were analysed after 12 weeks: a filtration test using a tracer showed no statistically significant difference between creatine and placebo. Forty-six people were originally assigned, so dropouts and the short follow-up limit the answer. The 2026 reviewers identified no trials in people with chronic kidney disease who were not on dialysis, and the small dialysis trials cannot rule out harm. Anyone with kidney disease or concerning results should discuss the specific product and tests with their clinician.34

What safety cannot be generalised

A study in healthy adults using a defined product is not a personalised clearance for someone with a medical condition or a multi-ingredient supplement. Product identity, other medicines and the reason for use all change the question; no regimen is given here. For the specific question about hair, see creatine and hair loss.12

If you are pregnant or breastfeeding, have kidney disease or another medical condition, or take medicines, ask a clinician or pharmacist about the exact product before using creatine. Many supplements have not been adequately studied during pregnancy or breastfeeding. For kidney blood tests, tell the clinician or laboratory about any creatine you already use.73