Creatine (Monohydrate)
Creatine helps your muscles make quick energy for short bursts of effort. With resistance training, it increases strength, power and lean muscle mass. Its effect on thinking and memory is less clear.
Creatine is made by the liver and kidneys (about 1 gram a day) from the amino acids glycine, arginine and methionine, and it also comes from foods such as meat, fish and dairy. Nearly all of the body's creatine is stored in skeletal and heart muscle, where it helps make ATP, supplying muscles with energy, particularly for short bursts of effort. Creatine monohydrate is the form used in the typical supplement protocol.
Research & evidence
Strong support Some support Weak or no supportColours show how well the sources back each point. The reason is next to each one.
Creatine monohydrate increases strength, power output, and lean muscle mass when combined with resistance training, though most of the underlying research has been conducted in men, and some studies suggest smaller gains in women.
Strong evidenceStrong support. Several trials or reviews agree
Study details
The ISSN 2017 position stand itself notes: "the majority of studies have been conducted on men and some studies suggest that women may not see as much gain in strength and/or muscle mass." This position stand's manuscript preparation was funded by the Council for Responsible Nutrition (a supplement-industry trade association), and several co-authors disclose creatine-industry financial ties (research funding, consulting, advisory board positions).
Source: 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." J Int Soc Sports Nutr. 2017 Jun 13;14:18. View source
Early evidence suggests creatine may support cognitive performance under conditions of sleep deprivation or mental fatigue (based on small trials); its effect in well-rested, healthy individuals is inconsistent and less supported — a widely cited 2024 meta-analysis reporting cognitive benefits has since been challenged on statistical grounds (double-counting of correlated outcomes from the same participants), a concern also raised independently by the European Food Safety Authority in 2024, which concluded no reliable conclusions could be drawn from that dataset.
Limited evidenceSome support. Based on one or a few small trials
Study details
One small trial (n=15, single dose) for sleep deprivation. Xu et al. 2024 (16 RCTs, 492 participants) reported significant effects on memory, attention time, and processing speed, but a formal published Commentary (2026) found a unit-of-analysis error — correlated outcomes from the same participants were pooled as if independent, which "is known to artificially inflate precision and statistical power." A near-identical error was previously found in a related creatine/memory meta-analysis (Prokopidis et al.); when correctly re-analyzed, the overall memory effect "was no longer significant, except in older adults." EFSA's own 2024 scientific opinion independently identified the same statistical problem in the Xu et al. dataset and "determined that no conclusions could be drawn based on that data" — a regulatory body's formal opinion, not just a competing paper.
Source: Xu C, Bi S, Zhang W, Luo L. "The effects of creatine supplementation on cognitive function in adults: a systematic review and meta-analysis." Front Nutr. 2024 Jul 12;11:1424972; Gordji-Nejad A, et al. "Single dose creatine improves cognitive performance and induces changes in cerebral high energy phosphates during sleep deprivation." Sci Rep. 2024;14:4891; Citherlet T. "Commentary: The effects of creatine supplementation on cognitive function in adults." Front Nutr. 2026 Apr 10;13:1716285 (also reporting EFSA's independent 2024 scientific opinion on the same dataset). View source
Creatine has a strong safety record across the range of durations most commonly studied (weeks to about a year), including no significant effect on glomerular filtration rate — the most clinically meaningful kidney function marker — in a 2025 meta-analysis of 21 studies. True long-term data (multiple years) are thinner than often implied; that same 2025 systematic review notes that "long-term safety data beyond one year remain sparse."
Moderate evidenceSome support. Studied only over weeks to about a year
Study details
Naeini et al. 2025 (BMC Nephrology, 21 studies): serum creatinine rose slightly but significantly overall, while GFR — the more clinically meaningful marker — showed "non-statistically significant differences... following creatine supplementation compared to control" (5 studies, 69 vs. 74 participants). The paper's own conclusion: "creatine is likely safe for kidney function in healthy individuals and various clinical populations when used within standard dosing protocols" — but its Limitations section states plainly: "Most included studies were of short to moderate duration; long-term safety data beyond one year remain sparse." The ISSN position stand's often-cited "up to 30 g/day for 5 years" language traces to a small number of individual long-duration studies, not a systematic synthesis at that timescale.
Source: Naeini EK, Eskandari M, Mortazavi M, Gholaminejad A, Karevan N. "Effect of creatine supplementation on kidney function: a systematic review and meta-analysis." BMC Nephrol. 2025 Nov 6;26:622; and Kreider RB, et al. ISSN position stand, J Int Soc Sports Nutr. 2017;14:18. View source
Dosage
| Form | Amount |
|---|---|
| Any form | A typical protocol in adults is a loading phase of 20 g a day of creatine monohydrate, split into four 5 g doses, for 5–7 days, then 3–5 g a day. Another approach skips loading and uses about 3–6 g a day for 3–4 weeks. |
Side effects
Weight gain from water is the most common effect. Less often, people get stomach upset, cramps or headaches.
Well documented Reported (case reports, anecdotal or one study) None reportedThe circle shows how well documented an effect is, not how serious it is. A rarely reported effect can still be serious, so always read ‘When to stop’.
| Effect | Frequency | When to stop |
|---|---|---|
| Weight gain from water retentionWell documentedListed plainly by NIH, MSK or LiverTox | Often | Stop and talk to a doctor if it bothers you. |
| Nausea, diarrhea, stomach upset or bloatingReportedDescribed as anecdotal by NIH or MSK | Uncommon; reported anecdotally | Stop and talk to a doctor if it persists. |
| Muscle cramps or heat intoleranceReportedDescribed as anecdotal by NIH or MSK | Uncommon; reported anecdotally | Stop and talk to a doctor if it persists. |
| HeadacheWell documentedListed plainly by NIH, MSK or LiverTox | Not stated | Stop and talk to a doctor if it persists. |
Safety & interactions
Safety
Creatine is considered safe for short-term use by healthy adults, and evidence shows that use for several years is safe. Studies have found no consistent side effects except weight gain, which comes from water retention, not body fat. Other reactions have been reported anecdotally and are uncommon: nausea, diarrhea and other stomach upset, muscle cramps and heat intolerance. Drinking enough fluids might help prevent them. MSK notes that regular caffeine intake may reduce creatine's benefits.
Contraindications
Neither MSK nor NIH lists contraindications for creatine. If you have a health condition or take medication, talk to your doctor before taking it.
Drug interactions
MSK says regular caffeine intake while loading creatine can interfere with creatine's benefits. NIH's fact sheet lists no drug interactions for creatine.
Established: stated plainly by an authoritative source. Documented: supported by case reports or trial data. Theoretical: based on mechanism, animal data, or a cautious listing. Always check with your pharmacist or prescriber.
Which form to buy
Creatine monohydrate
Good choiceThe form most used in the research
The most widely used and studied form.
Other forms (creatine ethyl ester, buffered creatine, creatine alpha-ketoglutarate, and others)
Works, with a catchNot proven better, and usually costs more
Usually more expensive, and not proven better than monohydrate at raising muscle creatine, or for digestion, product stability or safety.