A recent comprehensive review published in Frontiers in Nutrition thoroughly evaluated these concerns, concluding that creatine is generally safe when used appropriately.
One major worry has been whether creatine increases cancer risk due to compounds called heterocyclic amines (HCAs), which form when creatine reacts with amino acids and sugars during high-heat cooking. While HCAs can be mutagenic at very high levels in lab models, the amounts in cooked meat and creatine supplements are significantly lower.
In fact, human studies have found virtually no increase in harmful HCA production from creatine supplementation. Interestingly, some research even suggests creatine may slow tumor growth and boost cancer-fighting immune cells, although results vary by cancer type and model.
Kidney health concerns arose decades ago, often from isolated cases involving people with pre-existing renal disease or other risk factors. However, a large body of strong human evidence now shows no harmful effects of creatine on kidney function in healthy individuals, even at doses up to 20 grams daily for years.
Creatine may raise serum creatinine-a marker of kidney stress-but other measures confirm stable kidney filtration. For those with significant kidney problems, caution and close monitoring remain advisable.
Claims that creatine causes dehydration or muscle cramps during exercise are largely unsupported; controlled trials show no negative impact on hydration, thermoregulation, or cramping. Gastrointestinal side effects, like bloating or diarrhea, can occur, especially at high single doses, but splitting intake or taking moderate doses usually prevents these issues.
Creatine’s safety in pregnancy remains unproven-animal studies suggest benefits, but human data are lacking, so supplementation is not currently recommended during pregnancy.
Overall, this review affirms that creatine monohydrate is one of the safest, most effective supplements when used properly and stresses choosing high-quality, third-party tested products to avoid contamination risks.
REFERENCE: Longobardi, I., Solis, M.Y., Roschel, H., Gualano, B. (2025). A short review of the most common safety concerns regarding creatine ingestion. Frontiers in Nutrition 12. DOI: 10.3389/fnut.2025.1682746. https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2025.1682746/full
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