Creatine

Few safety concerns have been reported at typical doses (e.g., a loading dose of 20 g/day for up to 7 days and 3–5 g/day for up to 12 weeks), per the NIH Office of Dietary Supplements. Reported adverse effects include weight gain due to water retention, plus anecdotal reports of nausea, diarrhea, muscle cramps, muscle stiffness, and heat intolerance. NIH NCCIH adds that there have been reports creatine may impair liver and kidney function and that it has been linked to an increased risk of compartment syndrome; it also states there are no data documenting the safety of creatine in children or adolescents, and that the American Academy of Pediatrics and the American College of Sports Medicine warn teens should not use performance-enhancing supplements, including creatine.

Creatine is produced endogenously (the body makes about 1 gram a day) and is obtained from the diet in small amounts from animal-based foods, such as beef and salmon (about 500 milligrams in a 4-ounce ), per the NIH Office of Dietary Supplements. Dietary supplements provide much larger amounts than can be obtained from food.

Per NIH NCCIH, people at risk of kidney problems should check with their health care providers before using creatine and be carefully monitored while using it; the ODS fact sheet lists no specific drug interactions for creatine.