Creatine monohydrate is the most studied form of creatine, a small nitrogen-containing compound that the body makes on its own and also gets from meat and fish. Muscle stores it mainly as phosphocreatine, a quick reserve for regenerating ATP (the cell’s immediate energy currency) during short, hard efforts. Sold as a dietary supplement, it is taken mostly to improve strength, power and gains from resistance training.
Creatine is not a drug and not a hormone. In the US it is a dietary supplement, which FDA does not approve before sale. The research base is large: dozens of randomized trials and several meta-analyses show modest gains in strength and lean mass when it is combined with resistance training. Large trials in Parkinson disease, Huntington disease and ALS found no benefit.
This page summarizes what randomized trials, meta-analyses and regulators report. It is for education only and is not medical advice.
| Property | Detail |
|---|---|
| Class | Dietary supplement; guanidino compound (not a steroid or hormone) |
| Formula | Creatine C₄H₉N₃O₂, 131.13 g/mol; monohydrate C₄H₁₁N₃O₃, 149.15 g/mol (≈88% creatine by weight) |
| Route | Oral powder or capsules |
| Doses used in studies | Loading: 20 g/day (5 g four times daily) for 5–7 days, then 2–5 g/day; or 3–5 g/day without loading |
| Half-life | No single meaningful value. Plasma creatine peaks ≈1 h after a 5 g dose; raised muscle stores take ≈30 days to return to baseline after stopping |
| Key mechanism | Raises muscle creatine and phosphocreatine by about 20–40%, supporting ATP regeneration in short, intense efforts |
| US status | Dietary supplement; FDA “no questions” letter on a GRAS notice for use in foods (GRN 931, 2020); not on the DEA Schedule III anabolic steroid list |
| WADA status | Not on the 2026 Prohibited List |
What it is
Creatine is made from two amino acids, arginine and glycine. The liver and kidneys build it in two enzyme steps, through an intermediate called guanidinoacetate (ISSN position stand, Kreider et al. 2017). Its chemical name is 2-[carbamimidoyl(methyl)amino]acetic acid (PubChem). The monohydrate form carries one water molecule per creatine molecule (PubChem), so 5 g of creatine monohydrate supplies about 4.4 g of creatine.
The ISSN position stand summarizes where creatine sits in the body:
| Fact | Value |
|---|---|
| Share stored in skeletal muscle | ≈95% (the rest mainly in brain and testes) |
| Share of muscle creatine held as phosphocreatine | About two thirds |
| Average muscle creatine, 70 kg person | ≈120 mmol/kg dry muscle |
| Apparent upper limit of storage | ≈160 mmol/kg dry muscle |
| Daily breakdown to creatinine | About 1–2% of the muscle pool |
| Daily replacement needed | About 1–3 g, roughly half from diet |
| Creatine in 1 lb (≈450 g) of raw beef or salmon | About 1–2 g |
On a normal mixed diet, muscle creatine stores are about 60–80% saturated, which is why supplementation can raise them. In the first human loading study, a single 5 g dose matched the creatine in about 1.1 kg of fresh uncooked steak (Harris et al., Clin Sci 1992).
During a sprint or a heavy set, phosphocreatine donates its phosphate to regenerate ATP. More stored phosphocreatine lets muscle sustain very high power a little longer. This is the main proposed reason creatine helps repeated short efforts and, over weeks, allows more training work.
Other forms are sold, including creatine ethyl ester, buffered creatine, creatine citrate and creatine nitrate. The ISSN reports that none has been shown to raise muscle creatine more than monohydrate.
Is creatine an anabolic steroid? No. Steroids are built on a four-ring carbon skeleton. Creatine is a small open-chain molecule with four carbon atoms, made from amino acids. It is not listed among the anabolic steroids in 21 CFR 1308.13.
How it works in the body
Creatine is probably absorbed actively from the gut, in a similar way to amino acids (Persky et al., Clin Pharmacokinet 2003). Plasma creatine peaks about an hour after a dose. Muscle takes it up through dedicated creatine transporters and effectively traps it. The rest is cleared by the kidneys or slowly converted to creatinine. Because muscle storage has a ceiling, the kinetics are nonlinear: once muscle is saturated, more of each dose is simply excreted.
The classic loading studies set the dosing used in most later trials:
| Study | Dose | Result |
|---|---|---|
| Harris et al. 1992 | Single 5 g dose | Mean plasma peak 795 µmol/L after 1 h (n = 3) |
| Harris et al. 1992 | 5 g four or six times daily for 2 or more days | Muscle total creatine rose significantly in 17 subjects; up to 50% in some, most in those starting low |
| Harris et al. 1992 | 6 × 5 g/day | 40–68% of the dose excreted in urine over the first 3 days |
| Hultman et al. 1996 | 20 g/day for 6 days | Muscle total creatine up ≈20% |
| Hultman et al. 1996 | Then 2 g/day for 30 days | Raised level maintained |
| Hultman et al. 1996 | Stopping after loading | Back to baseline by 30 days |
| Hultman et al. 1996 | 3 g/day for 28 days, no loading | Same ≈20% rise, reached more gradually |
Two practical points follow from these data:
- Loading is faster, not stronger. A low daily dose reaches the same muscle level as loading, just over about four weeks instead of one.
- “Half-life” is not a useful number here. Plasma creatine clears within hours, but the muscle store, which drives the effect, falls over about a month after stopping.
Regulatory status
In the US, creatine monohydrate is sold as a dietary supplement. Under the Dietary Supplement Health and Education Act, FDA does not have the authority to approve dietary supplements before they are marketed, and manufacturers do not have to show FDA safety evidence before sale (FDA).
For use as a food ingredient, FDA reviewed a GRAS (generally recognized as safe) notice from the manufacturer AlzChem and closed it with a “no questions” letter on November 12, 2020 (FDA GRN 931). That notice covers 1.2 g creatine monohydrate (1.0 g creatine) per serving in foods such as protein bars, powders and drink mixes. It does not cover supplement doses.
Creatine is not a prohibited substance in sport. It does not appear on the WADA 2026 Prohibited List.
What the research shows
Strength
Two meta-analyses from the same group pooled placebo-controlled randomized trials of strength tests lasting under 3 minutes. Effect sizes are standardized differences between creatine and placebo groups at the end of supplementation.
| Outcome | Studies (creatine vs placebo n) | Effect size (95% CI) |
|---|---|---|
| Global lower-limb strength | 60 (646 vs 651) | 0.235 (0.125–0.346) |
| Squat | — | 0.336 (0.047–0.625) |
| Leg press | — | 0.297 (0.098–0.496) |
| Global upper-limb strength | 53 (563 vs 575) | 0.317 (0.185–0.449) |
| Bench press | — | 0.265 (0.132–0.398) |
Lower limb: Lanhers et al., Sports Med 2015. Upper limb: Lanhers et al., Sports Med 2017.
These are small but consistent effects. In both analyses, meta-regression found no link between the benefit and age, sex, training status, loading, total dose or duration.
Lean body mass
A 2022 meta-analysis pooled 35 randomized trials with 1,192 participants, excluding people with specific diseases (Delpino et al., Nutrition 2022):
| Comparison | Extra lean body mass vs placebo (95% CI) |
|---|---|
| All studies | +0.68 kg (0.26–1.11) |
| With resistance training | +1.10 kg (0.56–1.65) |
| With mixed exercise | +0.74 kg (−3.89 to 5.36), not significant |
| Without exercise | +0.03 kg (−0.65 to 0.70), not significant |
| Men | +1.46 kg (0.47–2.46) |
| Women | +0.29 kg (−0.43 to 1.01), not significant |
The key point is that creatine works with training, not instead of it. Without exercise, lean mass did not change.
Some of the early weight gain is water drawn into muscle along with creatine. Methods such as DXA count that water as lean tissue. A meta-analysis limited to trials that measured muscle directly by MRI, CT or ultrasound found a very small benefit: a pooled standardized effect of 0.11 (95% credible interval −0.02 to 0.25) across 10 studies, or about 0.10–0.16 cm of extra muscle thickness (Burke et al., Nutrients 2023).
Older adults
A meta-analysis of 22 randomized trials in 721 older men and women (mean ages 57–70) combined creatine with resistance training 2–3 days a week for 7–52 weeks (Chilibeck et al., Open Access J Sports Med 2017):
| Outcome | Creatine vs placebo (95% CI) |
|---|---|
| Lean tissue mass | +1.37 kg (0.97–1.76) |
| Chest press strength | SMD 0.35 (0.16–0.53) |
| Leg press strength | SMD 0.24 (0.05–0.43) |
SMD is the standardized mean difference, the same kind of effect size as in the strength table above.
Cognition
A 2024 meta-analysis of 16 randomized trials with 492 adults, all using creatine monohydrate, found a small improvement in memory: SMD 0.31 (95% CI 0.18–0.44), rated moderate certainty (Xu et al., Front Nutr 2024). It found no improvement in overall cognitive function or executive function. Signals for attention and processing speed were rated low certainty. The trials were small and mixed healthy people with patient groups, so this is an early finding, not an established effect.
Neurological and muscle diseases
Creatine was tested in several diseases after promising results in animal models. Large trials in neurodegenerative disease were negative:
| Condition | Trial | Dose | Result |
|---|---|---|---|
| ALS | Cochrane review, 3 RCTs, 386 patients (Pastula et al. 2012) | 5–10 g/day | No difference in survival or functional decline |
| Huntington disease | CREST-E, 553 patients, up to 48 months (Hersch et al., Neurology 2017) | Up to 40 g/day | Stopped for futility; functional decline 0.82 points/year on creatine vs 0.70 on placebo |
| Parkinson disease | NET-PD LS-1, 1,741 patients, ≥5 years planned (NET-PD Investigators, JAMA 2015) | 10 g/day | Stopped for futility; no difference in clinical decline |
| Muscular dystrophies | Cochrane review, 6 RCTs, 192 patients (Kley et al. 2013) | Varied | Muscle strength +8.47% vs placebo (95% CI 3.55–13.38) |
The muscular dystrophy result is the one clinical area with a consistent benefit in randomized trials. The same Cochrane review found no strength benefit in metabolic myopathies.
Side effects and risks
The ISSN position stand reports that the only consistently reported side effect in the literature is weight gain. Early studies found that loading caused short-term fluid retention of about 0.5–1.0 L, roughly in proportion to the weight gained. Note that the ISSN position stand and several of the trials and reviews cited here were written by researchers who disclose funding from, or advisory roles with, creatine manufacturers.
Kidney function and the creatinine problem
Creatine breaks down to creatinine, the blood marker doctors use to estimate kidney function. Supplementation therefore raises serum creatinine without necessarily harming the kidneys. This can make a routine estimated GFR (eGFR) look worse than true kidney function.
A 2026 meta-analysis of randomized trials found (Tsiaras et al., J Ren Nutr 2026):
| Marker | Creatine vs control (95% CI) | Trials |
|---|---|---|
| Serum creatinine | +0.13 mg/dL (0.07–0.18) | 19 |
| Urea | −0.60 mg/dL (−2.15 to 0.96), no difference | 12 |
| eGFR | −5.20 mL/min/1.73 m² (−15.00 to 4.60), no difference | 8 |
The authors concluded that the creatinine rise did not come with changes in urea or eGFR, and called for trials longer than 1 year. Anyone taking creatine who has kidney tests should tell the clinician, since the result may need interpreting. The ISSN notes that some experts advise people with existing kidney disease to consult a physician before use.
DHT and hair loss
The hair loss concern traces to one small study. In a crossover trial of 20 college rugby players, loading with 25 g/day for 7 days raised DHT (dihydrotestosterone, a potent androgen linked to male-pattern baldness) by 56%, and DHT stayed 40% above baseline after 14 days at 5 g/day (van der Merwe et al., Clin J Sport Med 2009). Testosterone did not change. Hair was not measured.
A 12-week randomized trial then tested 5 g/day against placebo in 45 resistance-trained men, 38 of whom finished (Lak et al., J Int Soc Sports Nutr 2025). It found no difference between groups in DHT, the DHT:testosterone ratio, hair density, follicular unit count or hair thickness. The trial was short and small, but it is the only one that measured hair directly, and it did not support the claim.
Cramping, dehydration and injury
In an open-label study across three seasons of NCAA Division I football, players chose whether to take creatine (15.75 g/day for 5 days, then about 5 g/day) (Greenwood et al., Mol Cell Biochem 2003). Creatine users made up 34–56% of players and accounted for 39% of cramping cases and 36% of heat or dehydration cases. Rates of injury were proportional to or lower than the share of users. The design was not randomized, so it cannot rule out differences between players who chose creatine and those who did not.
Gastrointestinal effects at high doses
In the Huntington disease trial, which used up to 40 g/day, adverse events, mainly gastrointestinal, were significantly more common on creatine than on placebo. Serious adverse events, including deaths, were more frequent in the placebo group.
Who should be cautious
- People with kidney disease or on regular kidney monitoring, because of the creatinine effect above and limited long-term data in this group.
- People with McArdle disease (a glycogen storage disorder). In one trial, high-dose creatine worsened daily activities and increased muscle pain.
- Adolescents. The ISSN considers use acceptable only for young athletes in supervised competitive training who eat a well-balanced diet and do not exceed recommended doses.
Quality and contamination
Because supplements are not approved before sale, product quality depends on the manufacturer. A Brazilian research group tested 149 creatine supplement samples by HPLC (a laboratory method that measures exact content) and classified 32 as adulterated (Oliveira et al., Food Chem 2025). FDA’s role is mainly enforcement after products reach the market (FDA).
Key takeaways
- A natural compound, not a steroid. The body makes about half of its daily creatine and gets the rest from meat and fish. About 95% is stored in muscle.
- Loading is optional. 20 g/day for about 6 days raises muscle creatine by about 20% within a week. 3 g/day reaches the same level in about four weeks.
- Real but modest benefits with training. Strength effect sizes are about 0.2–0.3, and lean mass gains average about 1 kg more than placebo with resistance training. Without exercise, the lean-mass change was not significant.
- No benefit in major neurological diseases. Large trials in Parkinson disease, Huntington disease and ALS were negative. Muscular dystrophy is the exception, with about 8% more strength.
- Expect a higher creatinine. Creatine raises serum creatinine by about 0.13 mg/dL without changing eGFR or urea in trials. That can mislead kidney tests.
- The hair loss link is unproven. One small 2009 study found higher DHT. A 2025 randomized trial found no change in DHT or hair measures.
Sources
- 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;14:18. PubMed.
- National Center for Biotechnology Information. Creatine, PubChem CID 586; creatine monohydrate, PubChem CID 80116. PubChem; PubChem.
- Harris RC, Söderlund K, Hultman E. Elevation of creatine in resting and exercised muscle of normal subjects by creatine supplementation. Clin Sci (Lond). 1992;83(3):367–374. PubMed.
- Hultman E, Söderlund K, Timmons JA, et al. Muscle creatine loading in men. J Appl Physiol. 1996;81(1):232–237. PubMed.
- Persky AM, Brazeau GA, Hochhaus G. Pharmacokinetics of the dietary supplement creatine. Clin Pharmacokinet. 2003;42(6):557–574. PubMed.
- Food and Drug Administration. Questions and answers on dietary supplements. FDA.
- Food and Drug Administration. GRAS Notice No. 931: creatine monohydrate (AlzChem Trostberg GmbH); closed November 12, 2020, “FDA has no questions.” FDA.
- Drug Enforcement Administration. Schedules of controlled substances: Schedule III. 21 CFR 1308.13. eCFR.
- World Anti-Doping Agency. World Anti-Doping Code International Standard: Prohibited List 2026. WADA 2026 Prohibited List.
- Lanhers C, Pereira B, Naughton G, et al. Creatine supplementation and lower limb strength performance: a systematic review and meta-analyses. Sports Med. 2015;45(9):1285–1294. PubMed.
- Lanhers C, Pereira B, Naughton G, et al. Creatine supplementation and upper limb strength performance: a systematic review and meta-analysis. Sports Med. 2017;47(1):163–173. PubMed.
- Delpino FM, Figueiredo LM, Forbes SC, et al. Influence of age, sex, and type of exercise on the efficacy of creatine supplementation on lean body mass: a systematic review and meta-analysis of randomized clinical trials. Nutrition. 2022;103–104:111791. PubMed.
- Burke R, Piñero A, Coleman M, et al. The effects of creatine supplementation combined with resistance training on regional measures of muscle hypertrophy: a systematic review with meta-analysis. Nutrients. 2023;15(9):2116. PubMed.
- Chilibeck PD, Kaviani M, Candow DG, et al. Effect of creatine supplementation during resistance training on lean tissue mass and muscular strength in older adults: a meta-analysis. Open Access J Sports Med. 2017;8:213–226. PubMed.
- Xu C, Bi S, Zhang W, et al. The effects of creatine supplementation on cognitive function in adults: a systematic review and meta-analysis. Front Nutr. 2024;11:1424972. PubMed.
- Pastula DM, Moore DH, Bedlack RS. Creatine for amyotrophic lateral sclerosis/motor neuron disease. Cochrane Database Syst Rev. 2012;(12):CD005225. PubMed.
- Hersch SM, Schifitto G, Oakes D, et al. The CREST-E study of creatine for Huntington disease: a randomized controlled trial. Neurology. 2017;89(6):594–601. PubMed.
- Writing Group for the NINDS Exploratory Trials in Parkinson Disease (NET-PD) Investigators; Kieburtz K, Tilley BC, Elm JJ, et al. Effect of creatine monohydrate on clinical progression in patients with Parkinson disease: a randomized clinical trial. JAMA. 2015;313(6):584–593. PubMed.
- Kley RA, Tarnopolsky MA, Vorgerd M. Creatine for treating muscle disorders. Cochrane Database Syst Rev. 2013;(6):CD004760. PubMed.
- Tsiaras A, Loufopoulos G, Theodoridis X, et al. The effect of creatine supplementation on kidney function: a systematic review and meta-analysis of randomized controlled trials. J Ren Nutr. Published online April 24, 2026. PubMed.
- van der Merwe J, Brooks NE, Myburgh KH. Three weeks of creatine monohydrate supplementation affects dihydrotestosterone to testosterone ratio in college-aged rugby players. Clin J Sport Med. 2009;19(5):399–404. PubMed.
- Lak M, Forbes SC, Ashtary-Larky D, et al. Does creatine cause hair loss? A 12-week randomized controlled trial. J Int Soc Sports Nutr. 2025;22(sup1):2495229. PubMed.
- Greenwood M, Kreider RB, Melton C, et al. Creatine supplementation during college football training does not increase the incidence of cramping or injury. Mol Cell Biochem. 2003;244(1–2):83–88. PubMed.
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