"Does creatine make you pee a lot?" draws about 3,600 searches a month, "does creatine make you thirsty" 1,900, "does creatine make you sweat more" 1,000, and the dehydration and cramp phrasings another 1,300. Behind all of them is one idea: creatine pulls water into muscle, so it must be pulling it from somewhere else. This page sets out what the hydration and heat trials measured, what the cramping data can and cannot show, the things nobody has measured, and the adverse-event reports read individually. It reports studies; it does not advise anyone how much to drink or take (how we work).
The short answer: creatine raises total body water, and in the trials that measured fluid balance and heat tolerance it did not dehydrate people. The trials did not find more cramping. Nobody has measured whether creatine makes people urinate more or feel thirstier, so those two questions have no direct answer in the literature.
| Question | What has been measured | What the measurements show |
|---|---|---|
| Does it dehydrate? | Blood and urine hydration markers, body-water volumes, heat-tolerance trials | No loss of fluid balance; body water rises |
| Does it cause cramps? | Injury logs in team sport, side-effect tallies across 685 trials | No excess, but the strongest data are unblinded |
| Does it make you sweat more? | Sweat loss during exercise in the heat | No change |
| Does it make you pee more? | Nothing — no trial recorded urine volume | Unknown |
| Does it make you thirsty? | Nothing — thirst never an outcome | Unknown |
Where the worry comes from
Creatine is stored inside muscle cells, and water follows it there. In a five-day loading trial of 24 aerobically trained men, the creatine group showed a significant increase in all body-water volumes measured by bioimpedance, while the placebo group did not change (Weiss and Powers, J Sports Med Phys Fitness 2006, PMID 17119520). In a 42-day trial in female college dancers, total body water rose from 32.2 to 32.7 kg on creatine (Brooks et al., JISSN 2023, PMID 36960692) — a gain of about half a litre, measured in seven women.
The leap from "water moves into muscle" to "the rest of the body runs dry" is the step the trials tested. It was given official weight in 2000, when a position statement from the American College of Sports Medicine advised people exercising intensely or in hot environments to avoid creatine. A 2008 review in the British Journal of Sports Medicine traced the cramp-and-dehydration belief to "media claims and anecdotal reports" and to that statement, and argued the later trials did not support it (Dalbo et al. 2008, PMID 18184753).
The heat and hydration trials
The most direct test is exercise in the heat, where a fluid deficit shows up as a higher core temperature and heart rate.
| Study | Who | What was given | What was measured | Result |
|---|---|---|---|---|
| Lopez et al. 2009, systematic review (PMID 19295968) | 10 randomised trials kept from 95 screened | Creatine at study doses | Heat tolerance, hydration status | "No evidence" that creatine hinders heat dissipation or fluid balance |
| Weiss and Powers 2006 (PMID 17119520) | 24 trained men | 5-day load vs placebo | Body water, core temperature, sweat loss, heart rate and blood pressure in a 60-min warm-room bout | Body water up; core temperature and sweat loss unchanged |
| Brooks et al. 2023 (PMID 36960692) | 13 female dancers | 0.1 g/kg/day for 42 days vs placebo | Total body water, lean mass | Body water +0.5 kg, lean mass up |
The systematic review graded its ten included trials at 7 to 10 out of 10 on the PEDro quality scale and concluded that controlled trials of athletes exercising in the heat "resulted in no adverse effects from creatine supplementation at recommended dosages" (Lopez et al., J Athl Train 2009). The review is from 2009; MuscleLedger found no later systematic review on the same question.
A limit stated plainly: these trials gave creatine to people who were drinking normally. None of them tested creatine in someone who was already dehydrated by illness, fluid restriction or weight cutting — the situation in the one serious case report below.
The population data that point the other way
One large observational study does not fit the reassuring picture neatly. Using NHANES dietary records from 98,681 Americans between 1999 and 2023, researchers found that both the lowest and the highest dietary creatine intakes were associated with altered blood osmolality, and higher intake with lower total, intracellular and extracellular water (Ostojic and Grasaas, Food Sci Nutr 2025, PMID 40585500). This is creatine from food — meat and fish — not supplements, it shows association rather than cause, and the first author discloses a creatine patent and creatine industry funding. It is reported here because it is the one dataset that questions the "creatine hydrates" line, and its own authors call for further research rather than a conclusion.
Cramps
Cramping is the complaint that started the reputation, and the evidence on it is unusual: the largest study is a team's injury log.
The football seasons. Across the 1998–2000 seasons of an NCAA Division I football programme, players chose whether to take creatine (15.75 g a day for five days, then about 5 g a day); between 34% and 56% of the squad did in any season. Athletic trainers logged every treated problem. Creatine users accounted for 37 of 96 cramping episodes (39%) and 8 of 28 heat or dehydration episodes (36%) — in proportion to, or below, their share of the team (Greenwood et al., Mol Cell Biochem 2003, PMID 12701814). A one-season follow-up in heat up to 37°C found users had significantly fewer cramps, heat illnesses and muscle strains than non-users (Greenwood et al., J Athl Train 2003, PMID 14608430).
Both studies were open-label: the players who chose creatine may have differed from those who did not, in conscientiousness, hydration habits or position. Both list Richard Kreider among the authors, who has disclosed industry-sponsored creatine research in later papers. They show that creatine users did not cramp more; they cannot show that creatine prevented cramps.
The trial tally. A 2025 analysis of 685 human creatine trials counted reported side effects. Muscle cramping or pain appeared in 2.9% of creatine study groups against 0.9% of placebo groups (p = 0.008). Counted by participants instead of by study, it was 0.52% against 0.07% (p = 0.085), not significant (Kreider et al., JISSN 2025, PMID 40198156). The full table of side effects from that analysis, and why the two counting methods diverge, is on creatine side effects. The lead author chairs the scientific advisory board of a creatine manufacturer, which the paper discloses.
Peeing more and feeling thirsty: not measured
These two phrasings carry the most searches and have the least evidence.
Urine volume. MuscleLedger searched PubMed on 2026-10-15 for creatine supplementation combined with "urine volume", "urine output" or "urinary volume". The search returned 12 records. None measured how much healthy people urinated while taking creatine; they concerned rhabdomyolysis case reports, crush injury, creatinine clearance and unrelated conditions. One, on creatine and urinary methylamine and formaldehyde, measured urine contents (Poortmans et al. 2005, PMID 16260971). The classic loading study likewise reported that urinary creatinine excretion rose with supplementation — the body clearing creatine's breakdown product — not urine volume (Hultman et al., J Appl Physiol 1996, PMID 8828669). Why that matters for blood and urine tests is set out on what creatinine on a blood test means.
So the honest position on "does creatine make you pee a lot" is that it has never been measured. What has been measured — body water going up — is the opposite of what more urination would do on its own, but that is an inference, not a finding.
Thirst. No trial MuscleLedger found reported thirst as an outcome. The 2025 analysis of 685 trials lists 49 side-effect categories evaluated; its abstract does not name thirst, and the full paper was not checked for it. Thirst is therefore neither confirmed nor ruled out.
Sweat
In the warm-room trial above, five days of creatine loading did not change sweat loss during 60 minutes of exercise (Weiss and Powers 2006). The 2008 review collected reports that creatine may slightly lower exercising heart rate and sweat rate in the heat, attributing it to the extra intracellular water (Dalbo et al. 2008). No trial found more sweating.
What FDA's adverse-event reports contain
Consumers and doctors can report suspected reactions to FDA, and the reports are published in the CFSAN Adverse Event Reporting System. MuscleLedger queried it through the openFDA food-event interface on 2026-10-15 (dataset last updated 2026-07-07) for reports naming a product whose brand name contains "creatine" and coding dehydration, muscle spasms, thirst, frequent urination or excessive urination. Eleven reports matched, dated 2009 to 2022.
| What the report named | Reports |
|---|---|
| Two or more products (typically creatine with protein, pre-workout, glutamine, vitamins or other supplements) | 7 |
| One product, a branded creatine blend | 2 |
| One product, a plain creatine monohydrate powder | 1 |
| One product, an older branded creatine powder, with a fatal outcome also coding raised blood methanol and liver injury | 1 |
The single plain-monohydrate report (2022) coded muscle spasms and twitching. Seven of the eleven coded dehydration, and six of those seven also coded vomiting, diarrhoea, kidney stones or reduced kidney function, where fluid loss could follow from the illness itself.
These reports cannot establish that creatine caused anything: they have no denominator, the person reporting decides what to list, and most named several products at once. A published analysis of 28.4 million adverse-event reports found 63% of the creatine-associated ones involved other forms of creatine or other supplements or drugs (Kreider et al. 2025).
The one case where fluid restriction mattered
A 2021 report from Columbia University describes a 25-year-old weightlifter who developed a clot in the central vein of one retina. Testing for clotting disorders was negative. He had taken creatine daily for five years "at a higher than recommended dose" and, at the time, was restricting water to lose weight. The authors concluded the clot occurred "in the context of creatine use and water restriction" (Moussa and Chen, Am J Ophthalmol Case Rep 2021, PMID 34169179). One case shows an association, not a cause, but it is the scenario the heat trials never tested: creatine combined with deliberate dehydration. Weight-cutting with creatine is covered separately on creatine while cutting.
What is not established
- Whether creatine changes how much or how often people urinate. Not measured.
- Whether it changes thirst. Not measured.
- Whether it is safe in people who are already dehydrated, restricting fluids, ill with vomiting or diarrhoea, or have kidney disease. Not tested in trials; the last group is discussed on creatine and kidneys.
- Whether the lower cramp rates in football users reflect creatine or the kind of player who chooses it. Not separable in an open-label study.
Anyone with symptoms of dehydration, persistent cramps or reduced urine while taking any supplement should see a clinician. The water creatine adds and the scale weight it causes are discussed on creatine bloating and does creatine make you gain weight; questions about drinks to mix it with are on what to mix creatine with.
Sources
All opened 2026-10-15.
- Lopez RM et al. "Does creatine supplementation hinder exercise heat tolerance or hydration status? A systematic review with meta-analyses." J Athl Train 2009;44(2):215–23. PMID 19295968
- Dalbo VJ et al. "Putting to rest the myth of creatine supplementation leading to muscle cramps and dehydration." Br J Sports Med 2008;42(7):567–73. PMID 18184753
- Weiss BA, Powers ME. "Creatine supplementation does not impair the thermoregulatory response during a bout of exercise in the heat." J Sports Med Phys Fitness 2006;46(4):555–63. PMID 17119520
- Brooks SJ et al. "Creatine monohydrate supplementation changes total body water and DXA lean mass estimates in female collegiate dancers." JISSN 2023. PMID 36960692
- Greenwood M et al. "Creatine supplementation during college football training does not increase the incidence of cramping or injury." Mol Cell Biochem 2003;244:83–8. PMID 12701814
- Greenwood M et al. "Cramping and injury incidence in collegiate football players are reduced by creatine supplementation." J Athl Train 2003;38(3):216–9. PMID 14608430
- Kreider RB et al. "Safety of creatine supplementation: analysis of the prevalence of reported side effects in clinical trials and adverse event reports." JISSN 2025. PMID 40198156
- Ostojic SM, Grasaas E. "Dietary creatine and hydration biomarkers in the general population: NHANES 1999–2023." Food Sci Nutr 2025. PMID 40585500
- Hultman E et al. "Muscle creatine loading in men." J Appl Physiol 1996;81(1):232–7. PMID 8828669
- Poortmans JR et al. "Effect of oral creatine supplementation on urinary methylamine, formaldehyde, and formate." Med Sci Sports Exerc 2005. PMID 16260971
- Moussa O, Chen RWS. "Central retinal vein occlusion associated with creatine supplementation and dehydration." Am J Ophthalmol Case Rep 2021. PMID 34169179
- FDA CFSAN Adverse Event Reporting System via openFDA food event API, queried 2026-10-15.