Is Creatine Bad for Your Kidneys?

No, in healthy kidneys — and the studies that settle it are the ones that measured filtration directly instead of estimating it from a blood test. In a 20-year-old man living with a single kidney, 35 days of creatine moved directly measured filtration from 81.6 to 82.0 mL/min/1.73 m², while the estimate calculated from his blood work fell from 88 to 71 mL/min/1.73 m².³ Same person, same month, two numbers heading in opposite directions. That gap is the whole kidney scare: creatine reliably raises the lab value doctors use to estimate kidney function, without changing the function itself. We sell nothing on this page, which is why it spends as much space on where the evidence runs out as on the part that reassures you.

The short answer

There is no evidence that creatine harms healthy kidneys at studied doses. The International Society of Sports Nutrition's position stand concludes there is "no compelling evidence that creatine supplementation negatively affects renal function in healthy or clinical populations" — in the same sentence that notes some have suggested people with pre-existing renal disease consult a physician first, "in an abundance of caution."¹ That second clause is part of the position, not a footnote to it, and this page keeps it attached everywhere it appears.

What confuses everyone is that creatine does move a kidney number. It raises serum creatinine, and serum creatinine is the input to every equation your lab uses to estimate filtration. So a lower eGFR on a creatine user's report can be the equation reacting to the supplement rather than the kidney reacting to anything. If you arrived here with a broader worry, every other creatine side effect claim gets the same treatment on its own page.

Two limits, stated up front rather than buried at the end: this applies to healthy kidneys, and the accurate long-term data runs to months, not decades.

Creatine and creatinine are not the same thing

One letter apart, and that letter is the whole confusion

Creatine is the compound you swallow and store in muscle as phosphocreatine. Creatinine is the waste product it decays into — spontaneously, non-enzymatically and irreversibly, at approximately 2% of the total body pool per day.² Your kidneys filter creatinine out of the blood, so how much is sitting in your blood is a proxy for how well they are filtering.

The proxy has an obvious weak point. It only works if you make creatinine at a steady rate. Put more creatine into the system and you make more creatinine, and the proxy reads a bigger backlog that was never there. Creatinine is not a toxin your kidneys are struggling to clear; it is an ordinary end-product of muscle metabolism that happens to be convenient to measure.

Why your eGFR moves when your kidneys don't

Estimating equations — Cockcroft-Gault, MDRD, CKD-EPI — take serum creatinine as their main input and assume production is stable. Supplementation breaks that assumption. The 2023 narrative review by Longobardi and colleagues lists creatine intake among the known confounders of creatinine-based eGFR, alongside muscle mass, diet, smoking, inflammation, medications, thyroid and corticosteroid hormones, and adiposity.²

The mirror image is the cleanest proof that the equation is reacting to diet rather than to kidneys: vegetarians run lower serum creatinine and creatinine clearance, because their dietary creatine intake is low.² Nobody suggests a vegetarian's kidneys are working unusually well. The number moved because the input moved.

So creatine is not a special case. It is one member of a well-catalogued class of things that shift a creatinine-based estimate without touching filtration.

One man, one kidney, two numbers

In 2010, Gualano and colleagues published something unusual: a young man with a single kidney and a mildly reduced GFR, already on a high-protein diet of 2.8 g/kg/day and resistance training, took creatine for 35 days — 20 g/day for 5 days, then 5 g/day for 30 — while his kidney function was tracked two ways at once.³ One way was an estimate from his blood. The other was ⁵¹Cr-EDTA clearance, which measures filtration directly.

Marker	Before	After
Measured GFR (⁵¹Cr-EDTA clearance)	81.6 mL/min/1.73 m²	82.0 mL/min/1.73 m²
Serum creatinine	1.03 mg/dL	1.27 mg/dL
Estimated creatinine clearance	88 mL/min/1.73 m²	71 mL/min/1.73 m²
Protein excretion	130 mg/d	120 mg/d
Albuminuria	4.6 mg/d	2.9 mg/d

Every figure in that table comes from that report.³ Do the arithmetic on the third row: 88 minus 71 is 17, and 17 divided by 88 is a 19% drop in estimated filtration. The measurement moved by 0.4 mL/min/1.73 m², which is noise. Protein and albumin in the urine went down, not up. The authors' own phrasing for the creatinine rise is that it was "falsely suggesting kidney function impairment."³

This is one person over five weeks, and that caveat belongs in the same breath as the numbers: it is the clearest illustration of the artifact anyone has published, and it is not evidence that creatine is fine with one kidney or with kidney disease. The randomized trials below carry the safety argument. This case carries the mechanism.

What happens when you measure filtration instead of estimating it

Measured GFR versus estimated GFR

An exogenous tracer such as ⁵¹Cr-EDTA is injected, freely filtered by the glomerulus, and neither reabsorbed nor secreted afterwards — so the rate it disappears from blood is the filtration rate, with no equation and no assumption about creatinine production in the middle. Creatine cannot touch that measurement by construction. That is why the following trials settle something a blood panel cannot.

Twelve weeks, high-protein diet, resistance training

Lugaresi and colleagues randomized resistance-trained adults eating at least 1.2 g/kg/day of protein to creatine — 20 g/day for 5 days, then 5 g/day — or placebo for 12 weeks, with ⁵¹Cr-EDTA clearance at baseline and at the end.⁴ Creatine went from 101.42 ± 13.11 to 108.78 ± 14.41 mL/min/1.73 m²; placebo went from 103.29 ± 17.64 to 106.68 ± 16.05; the group-by-time interaction was F = 0.21, p = 0.64.⁴ Creatinine clearance, serum and urinary urea, electrolytes, proteinuria and albuminuria "remained virtually unchanged."⁴

That combination matters, because high protein intake is the other thing people are told strains the kidney. Here it was stacked with creatine for three months, in the group most likely to be doing both, and filtration did not budge.

Twelve weeks in people with type 2 diabetes

The same group ran a randomized, double-blind trial in patients with type 2 diabetes — a population carrying a genuine risk factor for kidney disease — for 12 weeks, again with ⁵¹Cr-EDTA clearance.⁵ Creatine 90.4 ± 16.9 → 96.1 ± 15.0 mL/min/1.73 m²; placebo 97.9 ± 21.6 → 96.4 ± 26.8; p = 0.58.⁵ Muscle phosphorylcreatine rose in the creatine group and not in placebo (44 ± 10 → 70 ± 18 vs 52 ± 13 → 46 ± 13 mmol/kg/wt, p = 0.03), which is how we know the participants actually took what they were given.⁵

Nothing here says creatine helps a metabolic condition, and nobody should read it that way. It says that in people with a risk factor, filtration was unchanged.

Three months, tracked with a marker creatine doesn't touch

A separate randomized trial gave 18 healthy sedentary men roughly 10 g/day of creatine or dextrose for three months alongside aerobic training, and tracked cystatin C rather than relying on creatinine alone.⁶ This one is not a tracer study — cystatin C is a blood marker, like creatinine — but it is a blood marker creatine has no way to inflate. Cystatin C fell in both groups over the 12 weeks (creatine 0.82 ± 0.09 → 0.71 ± 0.06 mg/L; placebo 0.88 ± 0.07 → 0.75 ± 0.09, P = 0.0001), which points to filtration rising slightly with training, not falling.⁶ Serum creatinine dropped with training in the placebo group and stayed flat in the creatine group — the artifact showing up exactly where you would predict it.⁶

Ten months to five years of real-world use

Poortmans and Francaux compared people who had been taking creatine for 10 months to 5 years against non-users, looking at plasma levels and urinary excretion of creatinine, urea and albumin, plus their clearances.⁷ No statistical differences between groups; glomerular filtration rate, tubular reabsorption and glomerular membrane permeability were normal in both.⁷ Their conclusion was that neither short-, medium-, nor long-term oral creatine induces detrimental effects on the kidney of healthy individuals.⁷

This is observational, not randomized, and it reaches further into real-world use than any trial does. The ISSN's own summary of the durability question is that there is no compelling scientific evidence that short- or long-term use of creatine monohydrate — "up to 30 g/day for 5 years" — has detrimental effects on otherwise healthy individuals or clinical populations who may benefit from it.¹ That review also describes a 21-month cohort of American football players taking 5–10 g/day, reporting no significant effect on creatinine or creatinine clearance versus controls.¹

What the pooled analyses found

A 2025 systematic review and meta-analysis in BMC Nephrology pooled 12 studies for serum creatinine, covering 177 people on creatine and 263 controls.⁸ Two findings, and they fit together: serum creatinine rose by a small, statistically significant amount, and GFR did not change significantly.⁸ The authors read that as "a modest, transient increase in serum creatinine levels, likely due to metabolic turnover rather than renal impairment."⁸

We are not printing the pooled effect size, and the reason is worth stating plainly: the abstract reports it in units that would make the rise biologically meaningless, which is almost certainly a typo rather than a result. The direction and the significance are solid; the absolute number is not, so it stays off this page until the full text resolves it.

The duration subgroups are the practically useful part. The creatinine rise was significant at a week or less, not significant across 1–12 weeks, and significant again past 12 weeks.⁸ The first of those windows is exactly a loading phase — the five days of 20 g/day a loading protocol calls for fall inside it. If you are not loading, 3–5 g a day is the ordinary dose, and it is a quarter of what these loading protocols use.

A second meta-analysis, from 2019 in the Journal of Renal Nutrition, screened 290 non-duplicated studies, carried 15 into qualitative analysis and 6 into quantitative, and concluded that creatine "does not induce renal damage in the studied amounts and durations."⁹ We are citing it for that conclusion and nothing else, because its abstract contradicts itself on the creatinine question: it states creatine did not significantly alter serum creatinine while reporting a standardized mean difference of 0.48 with a 95% confidence interval of 0.24 to 0.73 and P = .001 — an interval that excludes zero, which is a significant increase, not an absence of one.⁹ The same pattern appears in its urea line. Pages quoting "no change in serum creatinine" from this paper are quoting the sentence and ignoring the statistic underneath it.

Who funds the research that clears creatine

The two most useful reviews on this topic are both from the same group, and you should know who pays them. Both disclose that Gualano has received research grants, creatine donations for scientific studies, travel support and speaking honoraria from AlzChem, a company that manufactures creatine, and that he serves on its scientific advisory board.²¹⁰ The 2025 paper adds that Roschel has received research grants and supplement donations from AlzChem and several other companies, and that AlzChem paid that article's publication charges — while stating the company had no hand in the analysis, the writing, or the decision to publish.¹⁰ That same group also ran two of the tracer trials above.

We are not going to pretend that is nothing. Here is why it doesn't overturn the picture: the reassuring result replicates across groups with no connection to each other — Poortmans and Francaux in Belgium in 1999,⁷ the football cohort described in the ISSN's American review,¹ and an independent Iranian meta-analysis in 2025.⁸ And the tracer method is hard to bend: ⁵¹Cr-EDTA clearance is an injected-tracer measurement read off an instrument, not a judgement call. Weight the funded work accordingly rather than discarding it or treating it as final.

Before your next kidney panel

Say the word "creatine" out loud

This is the one action the evidence actually supports. Tell whoever is ordering the test that you supplement with creatine, so the result gets interpreted with that on the table.

The reason to bother is that an unexplained creatinine bump does not stay a number. It triggers a repeat panel, sometimes a referral, occasionally a note in your chart that follows you for years. And it cuts the other way too, which almost nobody says: if the artifact can invent a problem that isn't there, it can also blur a real change that is. Neither of those is a reason to be scared of a blood test — it is a reason to make sure the person reading it knows what you take.

Cystatin C is a marker creatine doesn't move

Cystatin C is a protein filtered by the kidneys whose production is not tied to creatine metabolism, so it gives a filtration estimate that supplementation doesn't distort. Longobardi's review makes it a formal recommendation: assessing kidney function with markers that are independent of creatine and creatinine metabolism is important to avoid misdiagnosis, meaning false positives.²

Take that as a question to raise with a clinician, not as a test to go buy. And be careful with a claim circulating on this topic: it is often asserted that creatine studies show cystatin-C-based eGFR holding steady while creatinine-based eGFR drops. We could not find a human creatine trial reporting that paired comparison. What exists is the principle, plus the three-month trial above where cystatin C was tracked and did not deteriorate.⁶

Should you pause creatine before a blood test?

Here is the honest answer, and it is the one page-one results won't give you.

Search this question and you will find confident, specific instructions to stop creatine for 1–2 weeks before a kidney panel, and equally confident instructions to stop for 24–48 hours. Neither cites anything, and they cannot both be right.

One controlled study has actually measured it, and almost nobody citing a washout number seems to know about it. In 2000, Schedel and colleagues gave ten athletes 30 g/day of creatine or placebo for six days in a randomized, double-blind design, then sampled again after seven days without it: serum creatinine rose about 20% on supplementation and was no longer different from baseline after the week off.¹¹ That is the whole primary-source basis for a washout window, and it is thinner than it sounds — five men per group, a dose six times an ordinary daily intake, and a single post-cessation measurement on day seven. It cannot tell you whether two days would have been enough, and it was designed for doping control, not for reading a kidney panel.

So this page still does not give you a number, because one sample at one week cannot license "stop for 24–48 hours" or "stop for a fortnight" as clinical advice. What is supported: the creatinine rise reflects metabolic turnover rather than kidney damage,⁸ and the fix for a misread result is context, not abstinence. Tell your clinician. If they want a filtration estimate that creatine cannot distort, that is a conversation about the marker they use, and it is theirs to have with you.

The case reports, one at a time

Eight published case reports link creatine to kidney injury. They are real, they are why this question refuses to die, and most pages either ignore them or count them. The 2023 review tabulates every one with what else was going on.²

Case	Patient and protocol	What else was going on
Pritchard & Kalra, 1998	25-year-old man; 15 g/day for 1 week, then 2 g/day for 7 weeks	Pre-existing kidney disease, and five years on cyclosporine — a drug known to be toxic to the kidney
Koshy and colleagues, 1999	20-year-old man; 20 g/day for 4 weeks; acute focal interstitial nephritis	No concomitant substances reported — and no clinical or training history either
Robinson and colleagues, 2000	24-year-old bodybuilder; 25 g/day for 12 months	Rhabdomyolysis with acute compartment syndrome after hours of lower-limb training
Barisic and colleagues, 2002	18-year-old with mitochondrial encephalopathy and moderate kidney impairment already; 20 g/day for 12 days, then 5 g/day for 28 months — prospective	Eight concurrent medications and supplements; the authors themselves suggest the decline followed the natural course of his disease
Révai and colleagues, 2003	22-year-old, reportedly a bodybuilder; reportedly 200 g/day	Roughly forty times a normal daily dose, taken alongside an anabolic steroid — and the review notes the kidney diagnosis was reported without any supporting test results
Thorsteinsdottir and colleagues, 2006	24-year-old bodybuilder; 15 g/day for 6 months; acute renal failure with interstitial nephritis	Large amounts of other supplements — herbs, non-herbals, vitamins — plus hours of strenuous training five times a week
Gualano and colleagues, 2010	20-year-old with a single kidney; 20 g/day for 5 days, then 5 g/day for 30 — prospective	Nothing. Measured GFR was unchanged; the creatinine rise falsely suggested impairment
Taner and colleagues, 2011	18-year-old bodybuilder; 20 g/day for 5 days, then 1 g/day for 6 weeks; acute tubular necrosis	Concomitant substances not reported

Every row above is read from that review's case table.² Two things follow from it, and only two.

First, six of the eight are retrospective. The supplement history is self-reported, and there is no pre-supplement baseline, so nobody can say whether kidney function was already abnormal before the person started. That is a limitation of the evidence, not proof the cases are meaningless. Only two were run prospectively, and neither points at creatine: in one, the reviewers' own reading is that an 18-year-old's decline tracked his underlying mitochondrial disease; the other is the single-kidney case above, where filtration was measured directly and did not move.²³

Second, these reports have not been debunked — they have been contextualised, which is a weaker and more honest claim. A case report generates a hypothesis; it cannot establish causation, especially when the same patient was on cyclosporine, or taking forty times the normal dose with a steroid, or hospitalised with rhabdomyolysis. The controlled trials are what answer the question. The case reports are what made it worth asking.

Where the evidence genuinely runs out

Six gaps, with nothing softened. Four of them are lifted straight from the 2023 review's own list of what the literature is missing.²

Existing kidney disease. The evidence here is very limited. The reviewers' own advisory is that people with a very low glomerular filtration rate caused by pre-existing kidney disease should refrain from creatine use.² That is their recommendation, reported as theirs — the decision is yours and your clinician's, and this page is not going to make it from a distance.

Long duration measured accurately. Studies running past about 16 weeks with accurate filtration methods are scant.² The five-year data is real, but it is observational and creatinine-based, not tracer-measured randomized data.⁷

Everything else people take. A large share of creatine users take several other substances at once, and the combined burden on the kidney has not been studied.² Look back at the case-report table: that is the single most common feature of it.

Forms other than monohydrate. Alternative formulations are much less studied, and one of them, creatine ethyl ester, is a more unstable molecule that favours increases in serum creatinine.² Everything on this page is about monohydrate.

Purity. Unapproved pharmaceutical ingredients have been detected in marketed supplements, and the reviewers advise avoiding untested products.² That is a finding, not a shopping recommendation — we are not naming a brand in a section about what nobody knows.

Adolescents and pregnancy. Long-term kidney data in under-18s is thin, and the 2025 short review states plainly that evidence is lacking for pregnant women.¹⁰ The ISSN's position that supervised creatine use is acceptable in adolescent athletes is about performance-context safety generally,¹ not about long-term kidney outcomes, and the two should not be run together.

Who should talk to a clinician first

Four groups sit outside the well-studied population, and for each of them this is a conversation to have rather than an instruction to follow:

• Anyone with existing kidney disease or a diagnosed reduction in kidney function, including a single kidney.
• Anyone taking medications that affect the kidneys — NSAIDs and other nephrotoxic drugs.
• People who are pregnant or breastfeeding, where the evidence is lacking.¹⁰
• Anyone under 18, where the long-term kidney record is thin.

The callout at the top of this page lists the same populations. This is educational information, not medical advice, and nothing here is a substitute for the clinician who can see your actual results.

Frequently asked questions

Is creatine bad for your kidneys?

There is no evidence of harm to healthy kidneys at studied doses, and the strongest evidence comes from trials that measured filtration with an injected tracer rather than estimating it from blood. Existing kidney disease is a separate and much less studied question that belongs with your clinician.

Does creatine raise creatinine levels?

Yes, and it is expected rather than alarming: creatine decays into creatinine, so taking more of it puts more of the byproduct into your blood. Because eGFR is calculated from serum creatinine, a higher reading can pull the estimate down without any change in actual filtration. We are not quoting a percentage, because no reliable one exists.

Should I stop taking creatine before a blood test?

Popular advice contradicts itself here — some pages say stop for one to two weeks, others say 24 to 48 hours, and neither cites anything. One small controlled study from 2000 found serum creatinine back at baseline a week after ten athletes stopped a 30 g/day course, but with five men per group and a single measurement on day seven it cannot establish a clinical washout window, let alone a shorter one. The supported step is telling your doctor you take creatine, so the result is interpreted with that on the table.

Can I take creatine if I have kidney disease?

That is a question for your clinician, not for a website. The evidence base in chronic kidney disease is very limited, and the reviewers who wrote the definitive narrative review advise that people with a very low glomerular filtration rate from pre-existing kidney disease refrain from creatine use. We report their recommendation; we do not issue one.

Does creatine damage kidneys long term?

The longest human record compared people using creatine for 10 months to 5 years against non-users and found normal glomerular filtration, tubular reabsorption and membrane permeability in both groups, and the ISSN's stated position covers up to 30 g/day for 5 years. The gap is tracer-measured randomized data beyond about 16 weeks, which does not yet exist.

My eGFR came back low and I take creatine — what does that mean?

It means the result needs to be interpreted by someone who knows you supplement. It does not tell you your kidneys are fine, and we are not going to tell you it is probably the creatine — the artifact can mask a real change as easily as it can invent a fake one. Say what you take, and let your clinician decide what the number means and whether to look further.

The bottom line

Three arrows, and almost every scary version of this question fuses two of them. Creatine raises serum creatinine: real, expected, understood. Higher serum creatinine lowers an estimated GFR: real, and it is arithmetic inside an equation rather than biology inside a kidney. Creatine damages kidneys: not demonstrated in healthy people, and every study that measured filtration with a tracer instead of inferring it from creatinine found no change.³⁴⁵

The one thing to actually do is tell your doctor you take it. The honest limits are that chronic kidney disease is barely studied, accurate measurement stops at a few months, and nobody has looked at what happens when creatine sits inside a stack of eight other things. If the pattern feels familiar, it should — it is the same shape as the other creatine scare that traces back to a single study.