Creatine is a compound the body uses to help regenerate ATP (cellular energy) for short, intense muscular effort; it is made endogenously (~1 g/day) and obtained from animal foods like red meat and fish. Sold as a dietary supplement, most commonly as creatine monohydrate, the most-studied form. It works by increasing muscle phosphocreatine stores.
Online, creatine is hyped for almost everything — bulking, fat loss, testosterone, "brain power," longevity, even hair. The honest reality is unusual for a supplement: for its CORE athletic use (short, intense, repeated effort and resistance-training adaptations) the evidence is genuinely strong, among the best of any sports supplement. But the effect size is modest, it works mainly alongside actual training, some people are "non-responders," it does little for endurance, and the trendy cognitive claims are real but early and smaller than social media implies. Supplements are not FDA-approved to diagnose, treat, cure, or prevent disease, and product quality varies (look for NSF/USP/Informed Sport third-party testing).
NIH ODS states creatine can increase strength, power, and maximum-effort muscle contraction, while noting the extent of improvement differs among individuals. A meta-analysis of 22 RCTs in older adults (721 participants; Chilibeck 2017, PMID 29138605) found creatine added to resistance training produced greater chest-press (SMD 0.35) and leg-press (SMD 0.24) strength gains than training alone. NCCIH concurs it 'may somewhat enhance' strength effects of exercise. Effects are modest, show up mainly with actual training, and response varies.
NIH ODS reports creatine enhances performance during repeated short bursts of intense, intermittent activity such as sprinting and weightlifting, and cites sprint-time improvements versus placebo. This is the best-supported claim.
Chilibeck 2017 meta-analysis (22 RCTs, older adults) found +1.37 kg lean tissue mass (95% CI 0.97-1.76) versus resistance training alone. Honest caveat: part of the early gain is intramuscular water retention, and creatine builds muscle by enabling harder training, not on its own without exercise.
NIH ODS states creatine seems to have little value for endurance activities, and added water weight can be a slight disadvantage. Not supported for aerobic endurance.
Genuinely mixed and early. Prokopidis 2023 (Nutrition Reviews, 8 RCTs, PMID 35984306): memory improved overall (SMD 0.29) but the effect was driven by older adults 66-76 (SMD 0.88) and was negligible in younger people (SMD 0.03). A 2024 meta-analysis (16 RCTs, 492 people, PMID 39070254) found significant benefit for memory, attention, and processing speed but NO significant effect on overall cognition or executive function, with GRADE certainty only moderate for memory and low for other domains. Avgerinos 2018 (PMID 29704637) reached similar 'may help short-term memory/reasoning, rest conflicting' conclusions. Promising for memory (especially older adults, vegetarians, stressed/sleep-deprived states), not established as a general brain enhancer; larger long-term trials needed.
Amounts commonly used in trials with creatine monohydrate (not a regulated or FDA-approved dose): optional loading of ~20 g/day split into 4 doses for 5-7 days, then 3-5 g/day maintenance (fills muscle stores faster); or no loading, 3-5 g/day from the start, reaching the same saturation in ~3-4 weeks with less GI upset and water-weight shift. Benefits depend on consistent daily use over weeks. "Advanced" forms (HCl, buffered) are not proven superior to plain monohydrate and cost more.
Generally well tolerated in healthy adults at typical intakes; the most common effect is weight gain from intramuscular water retention. A 2025 short safety review (PMID 41404326) found no supported link to cancer, dehydration, or exercise cramps, with GI distress being dose-dependent (mainly at higher/loading doses). Kidneys: creatine raises serum creatinine (a lab marker), but a 2025 meta-analysis (PMID 41199218) found this reflects metabolic turnover, not kidney damage, with no significant change in GFR in healthy people — tell your provider you take creatine before a blood test so an elevated creatinine is not misread. IMPORTANT COMPLETENESS CAVEAT: NCCIH notes there have been reports of creatine impairing liver and kidney function and an association with compartment syndrome, and states its long-term effects have not been well studied — so blanket "no serious problems" reassurance is not fully supported. Who should be cautious or avoid: people with existing kidney disease or risk factors (consult a clinician and be monitored, per NCCIH); pregnant or breastfeeding people (evidence lacking); and children/teens — the American Academy of Pediatrics and American College of Sports Medicine advise against performance-enhancing supplements, including creatine, in adolescents. Interactions: no drug interactions are well documented; the commonly cited cautions about combining with kidney-stressing drugs (NSAIDs) and about high caffeine potentially blunting benefit come from Mayo Clinic/Merck (outside this record's strict authoritative allow-list) and should be treated as secondary. Not FDA-approved to treat any disease.
Creatine monohydrate is one of the few supplements where the honest answer is "yes, it works" for its core purpose: increasing strength, power, and performance in short, intense, repeated effort, and adding modestly to muscle-mass and strength gains when you actually resistance-train. It does little for endurance. Its cognitive benefits are real but early — best evidence is for memory, especially in older adults — and it is not a proven general brain enhancer. It is inexpensive and well tolerated by most healthy adults, but people with kidney disease should check with a doctor first, it is not recommended for pregnancy/breastfeeding or adolescents, and it can throw off a creatinine blood test. Monohydrate is the form to buy.
General information, not medical advice. Dietary supplements are not FDA-approved to treat, cure, or prevent any disease, and quality/purity vary by brand. Talk to your clinician or pharmacist before starting one — especially if you’re pregnant, breastfeeding, or take other medicines.