Creatine
Creatine monohydrate
Written by Aaron CuhaReviewed Sep 2026
Also known as: Creatine monohydrate, CrM
The most studied supplement there is, with a solid strength effect, a smaller hypertrophy effect than marketing implies, and a cognition claim a regulator has formally rejected.
Overview
Creatine is a compound your body makes and you also eat in meat, stored in muscle as phosphocreatine and used to regenerate ATP during short intense efforts. Its effect on strength and work capacity is real and about as well established as anything in this catalogue. Two things are less well established than the marketing suggests. When muscle growth is measured by direct imaging rather than by whole-body composition, the pooled effect is small and its credible interval crosses zero. And the cognition claim, which now drives a large share of sales to older adults, was formally evaluated by the European Food Safety Authority at the request of a creatine manufacturer, and the regulator ruled the claim was not causally established.
Mechanism of action
Loads muscle phosphocreatine, which regenerates ATP from ADP during high intensity work lasting seconds. That raises work capacity per session, and the extra work done over months is the likely route to most of the strength gain rather than any direct anabolic action.
Human evidence
Extensive. Hundreds of randomised trials, which makes creatine unusual in this catalogue: the question is not whether human data exists but what it actually shows once you separate the outcomes.
- Strength and high intensity work capacity: consistently improved across decades of trials. This is the claim that holds.
- Hypertrophy: when measured by direct imaging rather than whole-body composition, the pooled effect is small and its credible interval crosses zero.
- Cognition in healthy rested adults: the largest randomised trial, 123 people, found no benefit, and the European regulator rejected the claim on a manufacturer's own dossier.
- Kidney function in healthy people: no trial evidence of harm, which is a well-supported negative.
- Loading is optional. Three grams a day reaches the same muscle saturation in about four weeks that twenty grams a day reaches in six days.
What this does not tell you: Nearly every favourable synthesis in this area has authors with industry ties, which is disclosed on the papers and worth knowing. The strength effect survives that scrutiny. The hypertrophy and cognition claims are where the gap between the marketing and the measurement is widest.
Reading the research record
Creatine is the rare case on this site where the problem is not a missing trial record. It is that a large, genuinely positive literature has been stretched to cover claims it does not support. The strength evidence is strong enough that creatine would be worth taking on that basis alone. The hypertrophy effect shrinks when you measure the muscle directly instead of inferring it from a whole-body scan, and the cognition claim was tested by a regulator at a manufacturer's own request and failed.
The hair loss story is the mirror image, a claim that circulates as established fact and rests on one 20 person study in rugby players that measured a hormone ratio and never looked at anybody's hair. It has not been replicated in the seventeen years since. Believing it requires the same credulity as believing the overclaims, pointed the other way.
The evidence, charted
Fig. 1 · evidence composition
2of 4 citations (50%) are in people
Counted from the citation list on this page. The Human count is the same number shown in the badge at the top. Both understate any literature larger than the sources we cite.
Fig. 2 · evidence over time
Evidence spans 3 distinct years, 2009 to 2024, counted from the citation list on this page.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four jurisdictions shown. A jurisdiction's classification is a regulatory fact, not a verdict on the science; see Legal status below for the full text and any notes.
Key studies & citations
- Review2023
The effects of creatine supplementation combined with resistance training on regional measures of muscle hypertrophy: a systematic review and meta-analysis
When hypertrophy is measured by direct site-specific imaging rather than whole-body composition, the pooled effect is small with a credible interval crossing zero. The age moderation runs toward younger adults, which is the opposite direction to how creatine is marketed for ageing.
Nutrients - Review2024
Creatine and improvement in cognitive function: evaluation of a health claim pursuant to article 13(5) of regulation (EC) no 1924/2006
The European Food Safety Authority assessed the cognition claim on a dossier submitted by a creatine manufacturer and concluded a cause and effect relationship was not established.
EFSA Journal - Human2023
The effects of creatine supplementation on cognitive performance: a randomised controlled study
123 participants, roughly half vegetarian. The trial reports no cognitive benefit, with more side effects in the creatine arm than placebo.
BMC Medicine - Human2009
Three weeks of creatine monohydrate supplementation affects dihydrotestosterone to testosterone ratio in college-aged rugby players
The single study behind the entire creatine and hair loss claim. It measured a hormone ratio in 20 rugby players over three weeks. It did not measure hair, and it has never been replicated.
Clinical Journal of Sport Medicine
What users report
Self-reported experiences, not evidence. Nothing below was measured under controlled conditions, and reports like these cannot separate a real effect from placebo, from the training or diet change that accompanied it, or from what the product actually contained. They are here because knowing what people describe, including what goes wrong, is worth reading alongside the studies.
- Water retention in the first week or two is near universal and is intracellular rather than subcutaneous.
- Gastrointestinal upset is common at high loading doses and generally resolves at a three to five gram maintenance dose.
- Hair loss anxiety is widespread in forums and drives many people to stop. The evidence behind it is one unreplicated study that never measured hair.
Sources: Strength training forums and supplement communities. Uncontrolled self-report, included for expectations rather than as evidence.
Frequently asked questions
Does creatine build muscle?
It reliably improves strength and how much work you can do in a session. The direct muscle growth effect is smaller than usually claimed: when growth is measured by imaging the muscle rather than by whole-body composition, the pooled estimate is small and its credible interval includes zero.
Does creatine help cognition?
Not in healthy rested adults on the current evidence. The largest randomised trial found no benefit, and the European Food Safety Authority rejected the claim on a dossier submitted by a creatine manufacturer. Sleep deprived and vegetarian subgroups are where any signal has been reported.
Does creatine cause hair loss?
There is one study behind that claim. It measured a hormone ratio in 20 rugby players over three weeks, it never measured hair, and nobody has replicated it since 2009. That is a thin basis for a belief this widespread.
Do I need to load?
No. Three to five grams a day reaches full muscle saturation in about four weeks. Loading gets you there in under a week and causes more stomach upset. Both end at the same place.
Is monohydrate worse than the expensive forms?
No comparison has shown a form that beats monohydrate on a clinical outcome. Monohydrate is the form nearly all the research used and it is the cheapest.