Does creatine cause constipation?

There is no evidence that it does, and nobody has tested it directly. We found no randomized trial that measured constipation as an outcome and no review of creatine and constipation. The closest evidence is a 2020 meta-analysis of 29 studies in 951 women, which found gut adverse events were no more common on creatine monohydrate than on placebo, with a risk ratio of 1.09 and a 95 percent confidence interval of 0.53 to 2.24. Constipation appeared only as one item in a list of gut complaints.

Unsettled. The honest answer is that constipation on creatine has never been counted on its own. In the 2020 meta-analysis, eight placebo-controlled studies reported gut symptoms, with 32 events on creatine and 19 on placebo. The difference was not significant, and the symptoms ranged from nausea and diarrhea to constipation and bloating, so the review cannot say how often constipation itself happened.

Share of players with diarrhea, percent

One double-blind randomized trial in 59 players. The abstract gives percentages without confidence intervals, so none are drawn. Only the 10 g group differed from placebo. Source: card ev-crcon-03 below.

What the trials found

When creatine upsets the gut in a trial, the complaint with a number attached is diarrhea, and it depended on how the dose was taken. In a double-blind randomized trial of 59 top-level male soccer players over 28 days, a single 10 g dose a day caused diarrhea in 55.6 percent of players against 35.0 percent on placebo. Splitting the same amount into two 5 g doses gave 28.6 percent, which did not differ from placebo. Constipation was not among the complaints the abstract names.

The larger safety reviews found little at all. A Cochrane review of 14 randomized trials in 364 people with muscle diseases found no trial that reported a clinically relevant adverse event. A 2026 meta-analysis of 7 randomized trials in 608 postmenopausal women, running 12 to 104 weeks, found adverse events were mild and similar to placebo. Neither abstract breaks the events down by type.

The two numbers that can be put on a risk scale

Controlled studiesObservational data

The top row is a risk ratio from controlled studies, and its interval spans no effect. The bottom row is an odds ratio per unit of creatine eaten in food, mostly meat, from a single survey that cannot show cause. Neither source gives absolute rates we could draw. Sources: cards ev-crcon-01 and ev-crcon-08 below.

The only data that look at constipation by name point the other way, and they are weak. In a cross-sectional analysis of 10,721 US adults in the NHANES survey, people who ate more creatine in food had 19 percent lower odds of chronic constipation per unit of creatine, with an interval of 0.65 to 0.96. That creatine came from meat and not from supplements. The survey measured everyone once, so it cannot show that creatine caused anything. The paper gives no absolute rates.

Who should be careful

Not for everyone. If creatine gives you gut trouble, how the dose is taken may matter. In the soccer trial, one 10 g dose a day caused more diarrhea than placebo and two 5 g doses did not. In a 5-day trial of 54 active men loading 20 g a day, four people reported mild stomach discomfort, all of them in the group taking creatine with caffeine. Nobody in the other groups reported side effects.

Older people with Parkinson disease are the one group where gut complaints stood out. In a 2-year randomized trial of 60 patients, 40 of them taking 4 g of creatine a day, creatine was well tolerated and the main side effects were gastrointestinal. The abstract does not say whether those complaints were constipation, diarrhea or something else, or how often they happened. We found no evidence on creatine and gut symptoms in pregnancy, in children or in people with kidney disease.

What expert bodies say

We found no expert body that comments on creatine and constipation in either direction. The European Union authorizes one claim for creatine: that it increases physical performance in successive bursts of short-term, high intensity exercise. It makes no gut claim, for or against.

How we searched

Searched: a local copy of the PubMed baseline for creatine with constipation, gastrointestinal, diarrhea, adverse events, side effects, bloating or stomach, across all study types (219 hits, top 40 screened, no meta-analysis or trial on constipation). A narrower search for creatine and gut symptoms returned 18 rows. We also searched the EU claims register, the US Office of Dietary Supplements, ClinicalTrials.gov for creatine and constipation, and the web for trials of creatine and gut side effects. Every cited study was checked against Retraction Watch. Search run on 7 October 2026.

Included: three meta-analyses of adverse events, three randomized trials that reported gut complaints, one cross-sectional survey analysis and the EU claim.

Excluded: a review of creatine in type 2 diabetes and a review of its interaction with caffeine, which add no gut data beyond the included trials. A kidney safety meta-analysis, which is about kidneys. Position stands and web summaries that list constipation as a side effect without primary data behind it.

What we read: the full text of the 2020 meta-analysis in women and of the NHANES analysis, and abstracts for the rest.

What we could not get: full texts of the soccer trial, the Parkinson trial and the caffeine trial, so the type of gut complaint in the Parkinson trial is unknown. The Office of Dietary Supplements has no creatine fact sheet in our copy, and ClinicalTrials.gov returned no trial for our query.

What would change this answer

A trial that reports constipation separately, with its rate on creatine and on placebo. Any large creatine trial could do this at almost no cost by using a standard bowel symptom questionnaire.
The breakdown of gut complaints in the 2-year Parkinson trial, which would show whether constipation was among them in older people.
A prospective study of creatine supplements, not dietary creatine, and bowel habits. The NHANES finding is about meat in a one-off survey and cannot answer the supplement question.

More on creatine, including what the trials on muscle, kidneys and cramps found: creatine →

The food behind this question

Creatine: a real strength gain when it is paired with training — numbers, evidence and safety

The same question for other foods (constipation)

Sources

ev-crcon-01 · Meta-analysis or systematic review · systematic review and meta-analysis · n = 951
There were no significant differences in total adverse events, (risk ratio (RR) 1.24 (95% CI 0.51, 2.98)), gastrointestinal events, (RR 1.09 (95% CI 0.53, 2.24)), or weight gain, (mean difference (MD) 1.24 kg pre-intervention, (95% CI -0.34, 2.82)) to 1.37 kg post-intervention (95% CI -0.50, 3.23)), in CrM supplemented females, when stratified by dosing regimen and subject to meta-analysis.
Who: female participants taking creatine monohydrate in studies that monitored adverse outcomes
Effect: gastrointestinal events RR 1.09 (95% CI 0.53 to 2.24); total adverse events RR 1.24 (0.51 to 2.98); no deaths or serious adverse outcomes
Certainty: Women only; GI events pooled together (constipation not analyzed separately). Full text PMC7353222 was read.
Nutrients, 2020 · checked 2026-10-07 · we read the abstract
ev-crcon-02 · Meta-analysis or systematic review · systematic review and meta-analysis, results section · n = —
Symptoms reported include nausea, vomiting, GIT discomfort, diarrhoea, constipation, irritable bowel, bloating, feeling of weight gain, dyspepsia, indigestion, decreased appetite.
Who: women in 8 placebo-controlled creatine studies reporting gastrointestinal symptoms
Effect: GI symptoms 32 in creatine groups vs 19 in placebo groups; no significant difference when stratified by dose; constipation not analyzed separately
Certainty: Constipation is only in the list of symptoms, without a separate frequency; this is the limit of knowledge (axis 9).
Nutrients, 2020 · checked 2026-10-07 · we read the fulltext
ev-crcon-03 · Randomized controlled trial(s) · double-blind randomized trial, 28 days · n = 59
Moreover, diarrhoea was more frequent in the C10 group as compared with the placebo group (55.6% vs. 35.0%, p < 0.05).
Who: top-level male soccer players, 28 days of creatine 2 x 5 g, 1 x 10 g, or placebo
Effect: diarrhea 55.6% (1 x 10 g) vs 28.6% (2 x 5 g) vs 35.0% (placebo); no difference in GI distress between 2 x 5 g and placebo
Certainty: Symptoms by survey; constipation not named among common complaints. No full text in PMC (no_pmc).
Res Sports Med, 2008 · checked 2026-10-07 · we read the abstract
ev-crcon-04 · Randomized controlled trial(s) · randomized placebo-controlled trial, 2 years · n = 60
Main side effects were gastrointestinal complaints.
Who: aged patients with Parkinson disease, creatine 4 g/day (n = 40) or placebo (n = 20) for 2 years
Effect: well tolerated; main side effects gastrointestinal complaints (type and rate not given in abstract); kidney markers normal
Certainty: The type of GI complaint (constipation or diarrhea) is not specified in the abstract; no full text.
Nutr Res, 2008 · checked 2026-10-07 · we read the abstract
ev-crcon-05 · Randomized controlled trial(s) · randomized trial, 5 days · n = 54
Four subjects reported mild gastrointestinal discomfort with CRE + CAF, with no side effects reported in other groups.
Who: physically active males, creatine 5 g four times a day alone or with caffeine or coffee, or placebo, 5 days
Effect: 4 participants with mild GI discomfort in creatine + caffeine group; no side effects in other groups
Certainty: Short high-dose intake; constipation not named.
J Strength Cond Res, 2016 · checked 2026-10-07 · we read the abstract
ev-crcon-06 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis of RCTs · n = 364
No trial reported any clinically relevant adverse event.
Who: people with muscular dystrophies, metabolic myopathies and inflammatory myopathies in RCTs of creatine
Effect: no clinically relevant adverse events in any trial
Certainty: Patients with myopathies, search up to 2012.
Cochrane Database Syst Rev, 2013 · checked 2026-10-07 · we read the abstract
ev-crcon-07 · Meta-analysis or systematic review · systematic review and meta-analysis of placebo-controlled RCTs · n = 608
Adverse events were mild and similar to placebo; renal indices were unchanged.
Who: postmenopausal women aged about 62, creatine with or without resistance training, 12 to 104 weeks
Effect: adverse events mild and similar to placebo; renal indices unchanged
Certainty: The type of adverse events is not detailed in the abstract.
J Int Soc Sports Nutr, 2026 · checked 2026-10-07 · we read the abstract
ev-crcon-08 · Observational data · cross-sectional analysis of NHANES · n = 10721
In Model 4, after adjusting for potential confounders such as sex, age, race/ethnicity, education, family income-to-poverty ratio, BMI, drinking status, smoking status, hypertension, diabetes, cardiovascular disease, and physical activity, the relationship between 2-day average dietary creatine intake and chronic constipation risk remained significantly negative (adjusted OR = 0.81, 95% CI: 0.65 ∼ 0.96, p = 0.015).
Who: US adults aged 20 and over, NHANES 2005-2010, 2-day dietary recall; constipation by Bristol stool type 1 or 2
Effect: chronic constipation adjusted OR 0.81 (95% CI 0.65 to 0.96) per unit of dietary creatine; chronic diarrhea risk about 4% higher per unit
Certainty: Creatine from food (meat), not supplements; cross-sectional design, causality not established. PMID 40786687 outside the corpus, text in the PMC database.
Front Nutr, 2025, Association of dietary creatine intake from meat protein sources with different types of intestinal problems: insights from NHANES 2005-2010 · checked 2026-10-07 · we read the fulltext
ev-crcon-09 · Position of an expert body · regulatory register entry · n = —
POL-HC-6365 Creatine Creatine increases physical performance in successive bursts of short-term, high intensity exercise Authorised
Who: EU Register of nutrition and health claims, claim POL-HC-6365
Effect: authorized
Certainty: The condition of use (3 g/day) is not given in the snapshot.
EU Register on nutrition and health claims, claim POL-HC-6365, snapshot 2026-09-21 · checked 2026-10-07 · we read the dataset

How this page was made. Evidence was extracted from primary sources into cards, every number was re-checked against the source, and the text was written from those cards. Bioma Learn has no human medical reviewer at this time, and we say so rather than invent one. Methodology. This is information, not medical advice.