Does creatine cause water retention, hair loss, or kidney damage, and which concerns have human evidence?

Creatine can increase body water and scale weight, particularly early in supplementation. That is not automatically the same as harmful generalized swelling or fat gain. Hair-loss concerns have relied heavily on a small older study reporting a hormone change rather than measuring hair loss. A more direct 12-week randomized trial found no significant creatine-related difference in the measured hair-health outcomes or androgen measures. This is reassuring, while still being a relatively short study rather than a lifetime guarantee for every person with hereditary hair loss.[1][2]

Kidney interpretation needs a similar distinction between a marker and actual function. Creatine use can complicate interpretation of serum creatinine, which feeds into common estimated filtration calculations. In a randomized study of resistance-trained adults consuming a high-protein diet, creatine did not worsen filtration measured directly by a clearance method over 12 weeks. This supports safety in the studied healthy population, not unrestricted use in established kidney disease. An abnormal kidney result should be evaluated in context, rather than dismissed or automatically blamed on creatine.[3]