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    Creatine explained: muscle, performance, safety and the brain

    Creatine is a compound stored mainly in muscle, and creatine monohydrate is among the most-studied sports supplements: research reviews find it increases high-intensity exercise capacity and lean mass during training.[1][2] Evidence for brain and ageing benefits is newer and weaker, and US supplements are not approved by FDA before sale.[3][4]

    Editor reviewedStrict sourcingUpdated ExplainerHealth and medicine, Sports, Aging and longevity biology

    Creatine is a compound the body makes and stores mostly in muscle, and creatine monohydrate is one of the most-researched supplements in sport.[1][2] Interest has widened from athletes to older adults and brain health, but the evidence differs a lot by claim.[5][3] This crash course starts here; the creatine page covers the compound, the evidence analysis weighs the claims, and the buyer’s guide covers products.

    This page is not medical advice. FDA advises talking to a doctor, pharmacist or other health professional before using any dietary supplement, in part because some interact with medicines.[6]

    What creatine is

    Your body makes some creatine and gets the rest from food like meat and fish. About 95% of it is stored in your muscles.[7][1] Supplements are studied mainly for short, high-intensity exercise.[2]

    About two-thirds of intramuscular creatine is phosphocreatine, the rest free creatine.[1] Roughly 1–2% of muscle creatine degrades to creatinine daily, so 1–3 g must be replaced each day, about half from diet and half from synthesis in the liver and kidneys from arginine and glycine.[7] On a normal diet, muscle stores are about 60–80% saturated; supplementation raises muscle creatine and phosphocreatine by about 20–40%.[8]

    Strength, muscle and performance

    The strongest evidence is for exercise. The International Society of Sports Nutrition (ISSN) says creatine monohydrate is the most effective supplement for increasing high-intensity exercise capacity and lean body mass during training.[2] In older adults, a 2021 meta-analysis found creatine plus resistance training increased muscle and strength more than training with a placebo.[5]

    The ISSN position stand is a review by a sports nutrition society; several authors of its 2021 follow-up review disclosed creatine-industry ties.[9] In the Forbes et al. meta-analysis of older adults, gains in lean tissue mass and strength with resistance training held regardless of dosing strategy, but chest-press and leg-press strength effects disappeared when loading-phase studies were excluded.[5][10] A 2021 review noted that two years of creatine without exercise did not increase lean mass in postmenopausal women.[11]

    Brain and ageing research

    Some studies suggest creatine may help memory, but the evidence is much less certain than for muscle.[12][3] A small 2025 pilot study in 20 people with Alzheimer’s disease reported that creatine was feasible and raised brain creatine, but it had no comparison group.[13]

    Xu et al. (2024) pooled 16 RCTs with 492 participants and found effects on memory, attention time and processing speed, but not on overall cognition or executive function; GRADE certainty was moderate for memory and low elsewhere.[12][3] A 2026 systematic review in adults aged 55+ found six studies, four of them cross-sectional diet surveys, with three rated poor quality.[14][15] That review drew a published letter in October 2026 challenging its methods.[16] The Alzheimer’s pilot (20 g/day for 8 weeks in 20 patients) reported an 11% rise in brain total creatine and improved scores on some tests, which its authors called preliminary.[13] See the evidence analysis for competing views. Broader longevity research is covered in the longevity crash course.[15]

    Safety

    The ISSN reports that weight gain is the only consistently reported side effect in the literature.[17] Early studies found loading caused short-term fluid retention of about 0.5–1.0 litres.[18] A 2021 review concluded that, at recommended dosages, creatine does not cause kidney damage in healthy people, and that most evidence does not link it to hair loss.[19][20] A 2025 randomised trial in 45 young men found no effect on DHT or hair measures over 12 weeks.[21] Creatine raises serum creatinine, a routine kidney blood test, without significantly changing filtration rate in meta-analyses; one asked for trials longer than a year.[22][23] Most of this research is in healthy people, so anyone with kidney disease or other conditions should ask a clinician.[19][6]

    Quality and regulation

    In the US, FDA does not approve dietary supplements before they go on sale; makers are responsible for their products and must follow manufacturing rules.[4][24] In 2025 a testing company reported that four of six creatine gummies it tested failed identity and potency checks, while all five powders passed.[25] In February 2026 FDA cited a supplement maker for an inadequate manufacturing record for its creatine powder.[26] Third-party programmes such as NSF Certified for Sport and Informed Sport test products against their labels and for banned substances; the buyer’s guide explains how to use them.[27][28]

    Health & medicine

    Creatine

    Creatine is a compound stored mostly in muscle and a widely studied sports supplement. What it is, where it comes from, and what research says about it.

    Developing in Health

    Questions readers ask

    What does creatine do?

    Creatine supplements raise the amount of creatine and phosphocreatine stored in muscle by about 20–40%. The International Society of Sports Nutrition says this can improve high-intensity exercise capacity and lean body mass during training.[8][2]

    Is creatine safe?

    The ISSN reports weight gain as the only consistently reported side effect and found no compelling evidence of harm in otherwise healthy people in studies lasting up to five years. Recent meta-analyses found raised serum creatinine but no significant change in kidney filtration; one called for trials longer than a year.[17][29][22][23]

    Does creatine cause hair loss?

    A 12-week randomised trial in 45 resistance-trained men found no difference between creatine and placebo in DHT levels or hair measures. A 2021 review said most evidence does not support a link.[21][20]

    Does creatine help memory or the brain?

    A 2024 meta-analysis found improvements in memory, attention time and processing speed but not overall cognition, and rated the evidence moderate for memory and low for the rest. A 2026 review in older adults called the evidence limited.[12][3][15]

    Does creatine make you gain water weight?

    Early studies found creatine loading caused short-term fluid retention of about 0.5–1.0 litres. A 2021 review concluded creatine does not always cause water retention.[18][20]

    Should teenagers take creatine?

    The ISSN said creatine use by younger athletes should be considered only for those in serious supervised training, eating a well-balanced diet, knowledgeable about appropriate use, and not exceeding recommended dosages. Talk to a clinician first.[30][6]

    Sources

    · 30 claims from 17 publishers

    Each numbered claim is a statement we checked against the sources listed with it. Tap a number in the text to see its sources in place.

    1. [1]

      About 95% of the body's creatine is stored in skeletal muscle, with small amounts in the brain and testes; about two-thirds of muscle creatine is phosphocreatine. confirmedas of 2017-06-13

    2. [2]

      The International Society of Sports Nutrition's 2017 position stand concluded that creatine monohydrate is the most effective nutritional supplement available to athletes for increasing high-intensity exercise capacity and lean body mass during training. confirmedas of 2017-06-13

    3. [3]

      The 2024 meta-analysis rated the certainty of evidence as moderate for memory and low for processing speed, overall cognition, executive function and attention. confirmedas of 2024-07-12

    4. [4]

      Under the Dietary Supplement Health and Education Act, FDA does not have the authority to approve dietary supplements before they are marketed. confirmedas of 2026-10-11

    5. [5]

      A 2021 meta-analysis found that creatine taken alongside resistance training increased lean tissue mass and strength in older adults more than placebo, regardless of dosing strategy. confirmedas of 2021-06-02

    6. [6]

      FDA advises consumers to talk to a doctor, pharmacist or other health care professional before buying or using a dietary supplement, partly because some supplements interact with medicines. confirmedas of 2026-10-11

    7. [7]

      About 1–2% of muscle creatine breaks down into creatinine each day and is excreted in urine, so the body needs to replace about 1 to 3 g of creatine a day; about half normally comes from the diet, and the rest is made mainly in the liver and kidneys from the amino acids arginine and glycine. confirmedas of 2017-06-13

    8. [8]

      On a normal diet containing 1 to 2 g of creatine a day, muscle creatine stores are about 60–80% saturated, and supplementation raises muscle creatine and phosphocreatine by about 20–40%. confirmedas of 2017-06-13

    9. [9]

      Several authors of the 2021 ISSN review disclosed ties to the creatine industry, including the lead position-stand author's role as chair of the scientific advisory board of Alzchem, a creatine monohydrate manufacturer. confirmedas of 2021-02-08

    10. [10]

      In the same meta-analysis, creatine had no greater effect than placebo on chest-press or leg-press strength once studies using a loading phase were excluded. confirmedas of 2021-06-02

    11. [11]

      The 2021 review concluded that creatine combined with resistance training produces most of the muscle and performance benefits seen in older adults, and noted that 3 g a day for two years without exercise did not increase lean mass in postmenopausal women. confirmedas of 2021-02-08

    12. [12]

      A 2024 meta-analysis of 16 randomised controlled trials with 492 adults found creatine monohydrate improved memory, attention time and processing speed, but not overall cognitive function or executive function. confirmedas of 2024-07-12

    13. [13]

      In a 2025 single-arm pilot trial, 20 patients with Alzheimer's disease took 20 g of creatine monohydrate daily for 8 weeks; brain total creatine rose 11% and some cognitive scores improved, which the authors called preliminary evidence. confirmedas of 2025-05-19

    14. [14]

      A 2026 systematic review of creatine and cognition in adults aged 55 and over found six studies with 1,542 participants; only two were double-blind supplementation trials and four were cross-sectional diet studies. confirmedas of 2026-02-01

    15. [15]

      Five of the six studies in the 2026 review reported a positive link between creatine and cognition, but only one was rated good quality, two fair and three poor; the authors called the evidence limited and asked for high-quality trials. confirmedas of 2026-02-01

    16. [16]

      In October 2026 Nutrition Reviews published a letter raising concerns about the methodological rigour and interpretation of the 2026 review of creatine and cognition in ageing, alongside a response from the authors. confirmedas of 2026-10-01

    17. [17]

      According to the ISSN position stand, weight gain is the only consistently reported side effect of creatine supplementation in the literature. confirmedas of 2017-06-13

    18. [18]

      Early studies found that creatine loading caused short-term fluid retention of about 0.5 to 1.0 litres, roughly proportional to the initial weight gain. confirmedas of 2017-06-13

    19. [19]

      A 2021 evidence review by ISSN-affiliated researchers concluded that creatine taken at recommended dosages does not cause kidney damage or dysfunction in healthy individuals. confirmedas of 2021-02-08

    20. [20]

      The 2021 review concluded that creatine is not an anabolic steroid, does not always cause water retention, does not cause dehydration or cramping, and that most evidence does not support a link with hair loss. confirmedas of 2021-02-08

    21. [21]

      A 12-week randomised controlled trial in 45 resistance-trained men aged 18–40 found no differences between creatine (5 g a day) and placebo in DHT levels or hair measures. confirmedas of 2025-04-23

    22. [22]

      A 2025 meta-analysis found creatine was associated with a small, transient rise in serum creatinine but no significant change in glomerular filtration rate, which the authors attributed to metabolic turnover rather than kidney impairment. confirmedas of 2025-11-06

    23. [23]

      A 2026 meta-analysis of 19 randomised trials and one crossover study found creatine raised serum creatinine by about 0.13 mg/dL without changing urea or eGFR, and called for trials longer than a year. confirmedas of 2026-04-24

    24. [24]

      FDA regulations require supplement makers, packers and holders to follow current good manufacturing practices meant to ensure the identity, purity, quality, strength and composition of supplements. confirmedas of 2026-10-11

    25. [25]

      In a June 2025 report, supplement-rating company SuppCo said it bought 11 creatine products (5 powders and 6 gummies) and had them tested by an ISO 17025-accredited lab; all 5 powders passed but 4 of the 6 gummies failed identity and potency testing. reportedas of 2025-06-12

    26. [26]

      In a 10 February 2026 warning letter, FDA told supplement maker Hearthy Foods that the master manufacturing record it supplied for its Creatine Powder was inadequate under federal manufacturing rules. confirmedas of 2026-10-11

    27. [27]

      Supplement makers describe the NSF Certified for Sport mark as meaning a product has been tested to match its label claims and to be free of banned substances; Thorne puts the screen at nearly 300 substances. confirmedas of 2026-10-11

    28. [28]

      Informed Sport, designed for elite athletes and drug-tested personnel, says it tests every batch of a certified product before release and screens for more than 300 compounds; its Informed Choice programme instead uses monthly retail monitoring. confirmedas of 2026-10-11

    29. [29]

      The ISSN position stand said there is no compelling scientific evidence that short- or long-term creatine monohydrate use, at up to 30 g a day for 5 years in the studies reviewed, harms otherwise healthy people or clinical populations who may benefit from it. confirmedas of 2017-06-13

    30. [30]

      The ISSN said creatine use by younger athletes should be considered only for those in serious supervised training, eating a well-balanced diet, knowledgeable about appropriate use, and not exceeding recommended dosages. confirmedas of 2017-06-13

    Revision history (1)
    1. Page created.

    Created Oct 11, 2026. Last reviewed by an editor on Oct 11, 2026. Next scheduled review: Jan 11, 2027.

    Cite this page

    "Creatine explained: muscle, performance, safety and the brain." ContentLora, updated Oct 11, 2026. https://contentlora.com/explain/creatine-explained

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