Creatine occupies an unusual position in the supplement world. It is the one compound where the sceptical position and the enthusiast position have largely converged: it works, the evidence is genuinely good, and it is remarkably safe. That consensus is correct.
It has also produced a strange situation in which the two things people most commonly worry about, kidney damage and hair loss, are among the least supported claims in the entire literature, while the caveats that do deserve attention go almost entirely unmentioned.
This is the full ledger. What creatine reliably does, how much it actually does it, where the popular claims outrun the trials, and what the genuine risks are.
What It Is and How It Works
Creatine is a compound your body already makes and already stores, which is worth establishing before anything else, because it reframes supplementation as topping up rather than introducing something foreign.
A 70 kg person carries roughly 120 g of creatine, with over 95 percent of it in skeletal muscle. About two-thirds is stored as phosphocreatine, the rest as free creatine. Your liver and kidneys synthesise around a gram a day from glycine, arginine and methionine, and an omnivorous diet supplies roughly another one to two grams, mostly from meat and fish.
The function is energy buffering over very short timescales. During brief maximal efforts, the enzyme creatine kinase transfers a phosphate group from phosphocreatine to ADP, regenerating ATP far faster than any other pathway can. This is the system that powers the first several seconds of a sprint or a heavy set. It is also why creatine does nothing much for a marathon: the phosphocreatine system is essentially irrelevant at that timescale.
On a normal diet, muscle creatine sits somewhere around 60 to 80 percent of capacity. Supplementation raises muscle total creatine by roughly 20 percent. Larger figures circulate, up to 40 percent, but these come from narrative reviews rather than direct biopsy measurement and should be treated as approximate rather than established.
Strength and Muscle: Real, Replicated, Modest
The evidence here is genuinely strong, and it is also genuinely smaller than the marketing implies. Both things are true and the second gets lost.
The foundational work is Branch's meta-analysis in the International Journal of Sport Nutrition and Exercise Metabolism in 2003, covering 100 studies. The effect size for body composition was 0.17 (plus or minus 0.03). For tasks lasting under 30 seconds, the ones the phosphocreatine system actually powers, it was 0.24. Upper body exercise showed the largest effect at 0.42. In the language of effect sizes, these are small.
Lanhers and colleagues later broke this down by region. Their 2015 analysis in Sports Med found lower limb strength effects of 0.336 for squat (95% CI 0.047 to 0.625) and 0.297 for leg press (95% CI 0.098 to 0.496). Their 2017 follow-up found an upper body chest press effect of 0.447 (95% CI 0.222 to 0.672).
For body composition, a 2024 meta-analysis of 12 randomised trials in the Journal of Strength and Conditioning Research found that creatine users gained on average 1.14 kg more lean body mass than those doing resistance training alone, and lost 0.7 kg more fat, regardless of training experience.
Roughly a kilogram of extra lean mass and a small but consistent strength advantage, on top of training. That is the honest headline. It is a real edge and it is not transformative, and anyone whose training and diet are inconsistent will get far more from fixing those than from any supplement.
How Much of the Early Gain Is Water
The scale jumps within the first week of creatine use, and the mechanism is not muscle.
Creatine is osmotically active and draws water into muscle cells. Powers and colleagues, publishing in the Journal of Athletic Training in 2003, found that creatine supplementation increased total body water without significantly changing the distribution between intracellular and extracellular compartments. The rapid one to two kilogram gain most people see is predominantly fluid.
Over months of training, genuine hypertrophy accrues, and that is what the 1.14 kg figure above reflects. But the first week is water, and expecting the scale to reflect muscle at that point sets you up to misread what is happening.
For most people this is cosmetically neutral or even favourable, since the water is inside muscle cells rather than under the skin. For anyone making a weight class, it is a genuine consideration.
Endurance: Where It Does Not Work, and May Hurt
This section rarely appears in creatine content, which is a shame, because it is one of the clearer findings.
Gras and colleagues pooled 19 randomised trials covering 424 individuals in Critical Reviews in Food Science and Nutrition in 2023 and found that maximal oxygen uptake increased in both groups, but increased less with creatine than with placebo (effect size -0.32, 95% CI -0.51 to -0.12, p=0.002). A small negative effect, not merely a null one.
Fernandez-Landa and colleagues reached the same conclusion in Sports Medicine in 2023: creatine monohydrate does not enhance endurance performance in trained individuals. And a 2024 trial in the Journal of the International Society of Sports Nutrition gave 20 g per day to 23 professional under-23 cyclists during a six-day training camp and found no benefit to recovery, body composition or field performance.
The likely explanation is straightforward: creatine adds one to two kilograms of body mass, which is a liability in any weight-bearing endurance activity, and the phosphocreatine system contributes almost nothing over those durations. Any benefit is confined to repeated sprint efforts or a finishing kick within a mixed-demand sport.
Dosing, and Why Loading Is Optional
Hultman and colleagues settled this in the Journal of Applied Physiology in 1996, and the finding has been widely ignored ever since.
Twenty grams per day for six days raised muscle total creatine by about 20 percent. Three grams per day for 28 days produced the same 20 percent increase. Loading is faster, not better. You reach the same destination either way.
The practical implication: three to five grams daily, taken consistently, is sufficient. Loading is worth considering only if you want saturation within a week, and it carries slightly more gastrointestinal discomfort and water weight. Cycling on and off has no basis in the evidence at all; the compound works by maintaining saturation, and coming off simply un-saturates you.
Timing relative to training does not appear to matter meaningfully. Consistency does.
Who Responds, and Who Does Not
Response is largely determined by where you start.
Vegetarians and vegans have lower baseline muscle creatine, since diet normally contributes one to two grams daily and theirs contributes almost none. They therefore have more room to fill and show larger increases. People who eat a lot of meat sit closer to saturation and gain less.
This is the basis of the non-responder phenomenon. It is not that creatine fails in these people; it is that they were already near the ceiling. If you eat a great deal of red meat and notice nothing, that is a coherent outcome rather than a mystery.
The Brain Claims, Read Carefully
Creatine has become a cognitive supplement in popular discourse, and this is where the gap between claim and evidence is widest.
The most-cited meta-analysis, by Xu and colleagues in Frontiers in Nutrition in 2024, pooled 16 randomised trials covering 492 participants. It found a significant benefit for memory (SMD 0.31, 95% CI 0.18 to 0.44) and for processing speed, but no significant effect on overall cognition or on executive function. Benefits concentrated in people who were unwell, and GRADE certainty was moderate for memory and low elsewhere.
That paper has also since drawn a published commentary in the same journal alleging a unit-of-analysis error from double-counting correlated outcomes. The finding may be more fragile than its citation count suggests, and honest coverage should say so.
The more interesting signal comes from stress conditions. Gordji-Nejad and colleagues, publishing in Scientific Reports in 2024, gave a single large dose of 0.35 g/kg during 21 hours of sleep deprivation and found improved cognition and processing speed alongside measurable changes in brain high-energy phosphates. Note the sample: 15 participants. Note also that the authors explicitly cautioned that doses that high are not advisable for routine home use.
There is a mechanistic reason for the modest results. Standard doses raise muscle creatine readily but raise brain creatine only slowly and slightly, because the blood-brain barrier limits uptake. The organ the cognitive claims are about is the one hardest to reach.
The defensible position: if you are vegetarian, older, or chronically sleep-deprived, there is a plausible case worth testing. If you are a well-rested omnivore expecting sharper thinking, the trials do not support that expectation.
Mood and Depression, Including a Safety Signal
The most encouraging trial is Lyoo and colleagues in the American Journal of Psychiatry in 2012: 52 women with major depressive disorder received escitalopram plus either creatine 5 g daily or placebo. The creatine group improved faster and reached roughly double the eight-week remission rate, 52 percent against 26 percent, with a large effect size.
A 2026 systematic review in Brain Medicine put that trial in context, covering five randomised trials with 238 participants across six countries. The results were mixed: two trials in women with major depression showed benefit, three, including one in antidepressant non-responders and one in bipolar depression, showed none. The trials were small, short, and skewed by sex, and the authors used narrative rather than pooled synthesis because the evidence would not support pooling.
One finding deserves to be stated plainly rather than buried. In a proof-of-concept trial of creatine as an adjunct in bipolar depression, two participants developed hypomania or mania. If you have bipolar disorder, this is a genuine reason to involve a clinician before supplementing rather than a theoretical caution.
Creatine is not a treatment for depression. Where it has shown promise it has been as an adjunct alongside standard treatment, and that is the only context in which the evidence supports considering it.
Older Adults, and the Bone Disappointment
Combined with resistance training, creatine augments outcomes in older adults. A 2025 meta-analysis in the European Review of Aging and Physical Activity, covering eight trials and 482 participants, found improvements in lower limb strength (SMD 0.29, 95% CI 0.00 to 0.57, p=0.05) and lean tissue mass (SMD 0.27, 95% CI 0.02 to 0.53, p=0.03) over training alone. Modest, and meaningful in a population losing muscle.
Bone is where the popular claim outruns the data. Forbes, Chilibeck and Candow pooled five trials with 193 participants in Frontiers in Nutrition in 2018 and found no benefit of creatine plus training over training alone for whole-body bone mineral density (mean difference 0.00, 95% CI -0.01 to 0.01), nor for hip, femoral neck or lumbar spine. A 12-month trial in older men likewise found no bone benefit beyond training, with only a non-significant trend for femoral neck bending strength.
A two-year trial in postmenopausal women is the most-cited positive result, which leaves a genuinely mixed picture. The confident assertion that creatine builds bone is ahead of the meta-analytic evidence.
The Kidney Myth
This is the most persistent fear and it rests on a misreading of a blood test.
Creatinine is the breakdown product of creatine. Take more creatine, produce more creatinine, and serum creatinine rises. Because the standard estimate of kidney function, eGFR, is calculated from serum creatinine, it appears to worsen. Nothing has happened to the kidney. The marker has been artificially inflated by the substrate feeding it.
Meta-analyses confirm the pattern: a small statistically significant rise in serum creatinine of roughly 0.13 mg/dL, with no meaningful change in urea or in measured kidney function. Long-term studies in healthy people have not found renal impairment.
Two practical consequences. If you supplement, tell any doctor ordering blood work, because an unexplained creatinine elevation can trigger an unnecessary workup. And if kidney function genuinely needs assessing in someone taking creatine, cystatin C is the appropriate marker rather than creatinine.
People with existing kidney disease are a different question. The small trials available have not shown harm, but long-term data are lacking, and this warrants a clinician rather than a blog.
The Hair Loss Scare, and Its Single Source
The claim that creatine causes hair loss traces to exactly one study, and it is worth knowing what that study did and did not do.
Van der Merwe, Brooks and Myburgh published in the Clinical Journal of Sport Medicine in 2009. Twenty college-aged rugby players took part in a double-blind crossover design. After a loading phase, dihydrotestosterone rose 56 percent, and remained about 40 percent above baseline during maintenance. DHT is the androgen implicated in male pattern baldness, so the inference was quick and obvious.
Now the parts that get omitted. The study had twenty participants. The DHT levels, despite rising, remained within the normal reference range throughout. And critically, the study never measured hair. Not hair density, not shedding, not follicle health, not a single hair-related outcome. It measured a hormone and stopped there.
More than fifteen years later, no study has replicated even the DHT finding, let alone connected creatine to actual hair loss. An entire widespread belief rests on twenty men, one unreplicated hormonal measurement, and an inference the study itself did not test.
If you are genetically predisposed to male pattern baldness you will likely lose hair whether or not you take creatine, and the evidence that creatine accelerates it does not currently exist.
The Cramping Myth, and the Real Side Effects
The belief that creatine causes cramping and dehydration is not merely unsupported; the evidence points the other way. Greenwood, Kreider and colleagues monitored 72 collegiate American football players and found that creatine users experienced fewer cramps, heat illnesses, muscle strains and total injuries than non-users.
The side effects that are real are less dramatic. Water retention and a gain of roughly one to two kilograms is expected and consistent. Gastrointestinal discomfort occurs, is dose-dependent, and is largely avoided by keeping individual doses to five grams or less rather than taking large single boluses. No adverse effects on liver markers have been found in healthy people.
Which Form, and the Contamination Problem
Monohydrate is the correct answer, and no alternative form has been shown to beat it.
Creatine ethyl ester performs worse, producing lower muscle creatine than monohydrate because it degrades to creatinine in the gut. Buffered creatine, sold as Kre-Alkalyn, showed no difference from monohydrate in a trial of 36 resistance-trained subjects across creatine content, training adaptations or side effects. Creatine hydrochloride dissolves better, which is a genuine convenience, but no independent trial demonstrates superior muscle loading or performance at effective doses. Nitrate and chelate forms offer no proven advantage.
The quality issue that actually matters is contamination. Moret and colleagues analysed 33 commercial creatine products in Food Chemistry in 2011 and found creatinine above 100 mg/kg in 44 percent of samples, with roughly 15 percent containing dihydrotriazine above the detection limit and dicyandiamide over 50 mg/kg. These are byproducts of the manufacturing process, and they are the reason to care about sourcing.
Buy third-party tested monohydrate. Creapure, NSF Certified for Sport, and Informed Sport are the meaningful marks. The premium over uncertified powder is small and it is the one place in this entire article where spending more is justified.
Where the Enthusiasm Runs Ahead
Several emerging applications are worth watching and not yet worth acting on.
Long COVID has produced small trials with some encouraging signals, but the most recent randomised trial found benefit at 6 g daily and, oddly, none at 18 g daily, which is internally inconsistent and hard to interpret. Traumatic brain injury has a strong mechanistic rationale, since injured brain tissue is energy-depleted, but a 2025 United States Department of Defense review concluded there are no large prospective placebo-controlled trials and no guidelines for its use.
The cautionary precedent is neurological disease. Large trials of creatine in Parkinson's and Huntington's disease, launched on genuinely strong mechanistic reasoning, ultimately failed to slow progression. Mechanism is not outcome, and this field has already learned that lesson once.
Where the Evidence Runs Out
A note on who writes the reviews. The International Society of Sports Nutrition position stand is the most comprehensive synthesis available and concludes that monohydrate is the most effective ergogenic supplement for high-intensity exercise. It also carries disclosed industry relationships, and several recent reviews on creatine in women were authored by scientific advisors to a creatine manufacturer. This does not invalidate the work, and independent meta-analyses broadly corroborate the exercise findings. It is a reason to weight independent analyses more heavily on the clinical and brain claims, where the industry-adjacent literature is notably more optimistic than the pooled trial data.
Long-term data beyond about a year are limited, chronic doses above ten grams daily are under-studied, and pregnancy data are thin. Women remain substantially under-represented across the whole literature.
And the effect sizes deserve one final restatement, because they are the thing most often lost. Strength effects between 0.17 and 0.45 are small. Creatine is an adjunct to training that works, reliably, at the margin. It is not a substitute for the training, the protein or the sleep that produce the results it modestly amplifies.
References
Harris RC, Soderlund K, Hultman E. Elevation of creatine in resting and exercised muscle of normal subjects by creatine supplementation. Clinical Science. 1992;83(3):367-374. doi:10.1042/cs0830367. PMID 1327657.
Hultman E, Soderlund K, Timmons JA, Cederblad G, Greenhaff PL. Muscle creatine loading in men. Journal of Applied Physiology. 1996;81(1):232-237. doi:10.1152/jappl.1996.81.1.232. PMID 8828669.
Branch JD. Effect of creatine supplementation on body composition and performance: a meta-analysis. International Journal of Sport Nutrition and Exercise Metabolism. 2003;13(2):198-226. doi:10.1123/ijsnem.13.2.198. PMID 12945830.
Lanhers C, Pereira B, Naughton G, et al. Creatine supplementation and lower limb strength performance: a systematic review and meta-analyses. Sports Medicine. 2015;45(9):1285-1294. doi:10.1007/s40279-015-0337-4. PMID 25946994.
Lanhers C, Pereira B, Naughton G, et al. Creatine supplementation and upper limb strength performance: a systematic review and meta-analysis. Sports Medicine. 2017;47(1):163-173. doi:10.1007/s40279-016-0571-4. PMID 27328852.
Burke R, Piñero A, Coleman M, et al. The effects of creatine supplementation combined with resistance training on regional measures of muscle hypertrophy and body composition. Journal of Strength and Conditioning Research. 2024;38(10):1813-1821.
Powers ME, Arnold BL, Weltman AL, et al. Creatine supplementation increases total body water without altering fluid distribution. Journal of Athletic Training. 2003;38(1):44-50. PMID 12937471.
Gras D, et al. Creatine supplementation and VO2max: a systematic review and meta-analysis. Critical Reviews in Food Science and Nutrition. 2023;63(21). PMID 34859731.
Fernandez-Landa J, Santibanez-Gutierrez A, Todorovic N, Stajer V, Ostojic SM. Effects of creatine monohydrate on endurance performance in a trained population: a systematic review and meta-analysis. Sports Medicine. 2023;53:1017-1027. doi:10.1007/s40279-023-01823-2.
Barranco-Gil D, et al. Effects of high-dose short-term creatine supplementation in professional cyclists. Journal of the International Society of Sports Nutrition. 2024;21(1):2340574. doi:10.1080/15502783.2024.2340574.
Xu C, Bi S, Zhang W, Luo L. The effects of creatine supplementation on cognitive function in adults: a systematic review and meta-analysis. Frontiers in Nutrition. 2024;11:1424972. doi:10.3389/fnut.2024.1424972. (See also the published commentary, Frontiers in Nutrition. 2026;13:1716285.)
Gordji-Nejad A, Matusch A, Kleedorfer S, et al. Single dose creatine improves cognitive performance and induces changes in cerebral high energy phosphates during sleep deprivation. Scientific Reports. 2024;14:4937. doi:10.1038/s41598-024-54249-9.
Lyoo IK, Yoon S, Kim TS, et al. A randomized, double-blind placebo-controlled trial of oral creatine monohydrate augmentation for enhanced response to a selective serotonin reuptake inhibitor in women with major depressive disorder. American Journal of Psychiatry. 2012;169(9):937-945. doi:10.1176/appi.ajp.2012.12010009.
Jeryous Fares B, Zhou C, Fabiano N, Wong S. Creatine as a treatment for depression: a systematic review. Brain Medicine. 2026. doi:10.61373/bm026l.0039.
Toniolo RA, Silva M, Fernandes FBF, et al. A randomized, double-blind, placebo-controlled, proof-of-concept trial of creatine monohydrate as adjunctive treatment for bipolar depression. Journal of Neural Transmission. 2017. doi:10.1007/s00702-017-1817-5.
Forbes SC, Chilibeck PD, Candow DG. Creatine supplementation during resistance training does not lead to greater bone mineral density in older humans: a brief meta-analysis. Frontiers in Nutrition. 2018;5:27. doi:10.3389/fnut.2018.00027.
Creatine supplementation combined with resistance training in older adults: a systematic review and meta-analysis. European Review of Aging and Physical Activity. 2025. doi:10.1186/s11556-025-00392-9.
van der Merwe J, Brooks NE, Myburgh KH. Three weeks of creatine monohydrate supplementation affects dihydrotestosterone to testosterone ratio in college-aged rugby players. Clinical Journal of Sport Medicine. 2009;19(5):399-404. doi:10.1097/JSM.0b013e3181b8b52f.
Greenwood M, Kreider RB, Melton C, et al. Creatine supplementation during college football training does not increase the incidence of cramping or injury. Molecular and Cellular Biochemistry. 2003;244(1-2):83-88. PMID 12701814.
Dalbo VJ, Roberts MD, Stout JR, Kerksick CM. Putting to rest the myth of creatine supplementation leading to muscle cramps and dehydration. British Journal of Sports Medicine. 2008;42(7):567-573.
Moret S, Prevarin A, Tubaro F. Levels of creatine, organic contaminants and heavy metals in creatine dietary supplements. Food Chemistry. 2011;126(3):1232-1238. doi:10.1016/j.foodchem.2010.12.008.
Kreider RB, Kalman DS, Antonio J, et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. Journal of the International Society of Sports Nutrition. 2017;14:18. doi:10.1186/s12970-017-0173-z.
Smith-Ryan AE, Cabre HE, Eckerson JM, Candow DG. Creatine supplementation in women's health: a lifespan perspective. Nutrients. 2021;13(2):877. doi:10.3390/nu13030877. PMID 33800439.