Does creatine damage your kidneys?
On the evidence we have, no, not in healthy adults at normal doses. But it will almost certainly make your kidney blood test look worse than it is, and that's a different problem, because it's the one that sends people to their GP in a panic over a result that was never really abnormal.
The short version: creatinine, the waste product your kidney test measures, is what creatine turns into when your body has finished using it. So taking creatine raises your creatinine by something like 10 to 30%, and because eGFR is calculated from creatinine, your estimated kidney function drops on paper even though your kidneys are filtering exactly as well as they were the week before. Controlled trials have looked for real kidney harm in healthy people taking normal doses and haven't found it. If you want an accurate reading while you're supplementing, ask for Cystatin C instead, because creatine has no effect on it.
In short
- Creatine raises serum creatinine by roughly 10 to 30%, because creatinine is what creatine breaks down into.
- eGFR is calculated from creatinine, so it falls on the report while your actual filtration hasn't changed.
- A 24% apparent drop in eGFR is enough to push a normal result into a category some labs flag as early kidney disease.
- Controlled trials in healthy adults at 3 to 5g a day have not found kidney damage.
- Cystatin C is the test to ask for if you're supplementing, because it isn't affected by creatine or muscle mass.
- Creatine doesn't dehydrate you, despite the advice everyone repeats. But being dehydrated does raise creatinine on its own, so it still matters on test day.
No doctor's referral, no appointment. Walk in Monday to Friday, 08:30 to 16:00, at our Cape Town lab in Observatory, our Johannesburg lab in Parktown North, or our Durban lab in Hillcrest. Results in 2 to 5 working days.
Why does creatine raise creatinine?
The names are confusingly similar and that's because the two are directly related. Creatine is stored in your muscles as a rapid energy reserve, and when your body has finished with a molecule of it, it breaks down into creatinine, which is a waste product your kidneys filter out and pass into your urine.
Standard kidney testing measures how much creatinine is sitting in your blood, on the assumption that if the level is high, your kidneys must be struggling to clear it. That assumption is usually sound and it's the basis of a test used millions of times a day, but it depends on your body producing creatinine at a fairly predictable rate. Take a supplement that raises your creatine stores by 20 or 30% and you're producing more creatinine to clear, which means the level in your blood goes up without your kidneys having changed at all.
A systematic review and meta-analysis published in 2025 found exactly that: a modest, transient increase in serum creatinine, which the authors put down to metabolic turnover rather than any loss of kidney function.
What does that look like on an actual report?
This is the part worth seeing rather than reading about, because the numbers are more alarming than the situation. Take a healthy 30 year old whose creatinine sits at 88 µmol/L, which gives an eGFR of about 100 and is entirely normal. He starts creatine, and his creatinine rises to 115 µmol/L.
Before creatine
88 µmol/L creatinine
100 eGFR
On creatine
115 µmol/L creatinine
76 eGFR
Illustrative figures based on the worked example in the literature, converted to the units South African laboratories report. In the American papers you'll see the same case written as 1.0 rising to 1.3 mg/dL.
That's a 31% rise in creatinine and a 24% apparent fall in eGFR, and an eGFR of 76 lands in a band that plenty of laboratory reports will flag as mildly decreased kidney function. Some reporting systems will nudge it towards a stage 2 chronic kidney disease label.
His kidneys have not changed. His real filtration rate is still around 100. What's happened is that the equation has been fed a number it was never designed to handle, because the whole calculation rests on the idea that a higher creatinine means less filtering, and creatine supplementation breaks that link.
Does creatine actually harm your kidneys?
The honest answer is that the controlled evidence in healthy people is reassuring, and the evidence in people who already have kidney disease is thin enough that nobody should be confident either way.
A narrative review of the whole question found that while there are a handful of case reports and some animal studies suggesting creatine might impair kidney function, clinical trials with controlled designs don't support the claim, and studies that assessed kidney function using reliable methods rather than creatinine alone found creatine safe for human consumption. The authors were explicit that further study is still needed in people with pre-existing kidney disease.
That distinction between reliable methods and creatinine alone is the crux of it. If you measure kidney function with the one marker creatine is guaranteed to inflate, you'll find a signal. If you measure it with something creatine doesn't touch, the signal disappears. Which tells you the signal was in the test, not in the kidneys.
The International Society of Sports Nutrition's position stand has held for years that creatine monohydrate at recommended doses is safe, and it remains among the most heavily studied supplements in existence.
Who should be more careful?
Three groups, and none of this is a reason for panic, just a reason to involve a doctor rather than deciding on your own.
Anyone with existing kidney disease
This is the genuine gap in the evidence. People with chronic kidney disease are routinely excluded from creatine studies, so the safety data doesn't really cover them, and the honest position is that we don't know rather than that it's fine. If you have known kidney disease, this is a conversation with your doctor before you start, not after.
Anyone on medication that affects the kidneys
Some prescribed medicines put a load on the kidneys of their own, and stacking an unknown on top of a known isn't sensible. Your doctor or pharmacist can tell you whether anything you're on falls into that category.
Anyone with symptoms rather than just a number
Swelling in your legs or face, foamy urine, passing much less urine than usual, or persistent nausea and confusion are not lab artefacts and they aren't things to explain away with a supplement. Those need a doctor promptly.
Do I need to drink more water on creatine?
Everyone says so, and the reasoning sounds solid: creatine pulls water into your muscle cells, so surely it's pulling that water from somewhere else and leaving you short. It's a tidy theory. It just doesn't hold up when anyone tests it.
A systematic review with meta-analysis in the Journal of Athletic Training pooled the controlled studies that measured hydration and thermoregulation in creatine users, in both normal and hot conditions, and found creatine did not reduce total body water as a proportion of body mass and did not impair the body's ability to regulate its temperature during exercise in the heat. One study went at the worst case directly, giving creatine to already-dehydrated men doing prolonged exercise in heat, and found it didn't compromise their hydration status or thermoregulation either.
The International Society of Sports Nutrition's position stand says plainly that there's no evidence creatine causes dehydration or cramping, and notes it may have a hyper-hydrating effect instead. A review of common creatine misconceptions went further and found that the creatine users in the studies examined had less cramping, heat illness and dehydration than the people not taking it.
So where does the advice come from? Partly from the plausible-sounding theory above, and partly from an old caution about creatine use in hot conditions that was issued without evidence behind it and then repeated for twenty years. Creatine does raise your total body water, with the extra water held inside your muscle cells, so your baseline requirement goes up a little. That's a reason to drink normally and sensibly rather than a reason to force litres down. It doesn't create an unusual demand.
There is one place where hydration genuinely matters here, though, and it's the whole subject of this article rather than the supplement.
Being dehydrated raises your creatinine on its own. Less fluid in your blood means a higher concentration of everything in it, creatinine included, so turning up to a kidney test dehydrated will push the number up in exactly the same direction creatine already has. Two artefacts stacked on top of each other, and a result that looks considerably worse than your kidneys are. That's worth avoiding whether you supplement or not.
What should I do before a kidney blood test?
You've got two options, and which one suits you depends on whether you're willing to interrupt your supplementing.
Option one: stop for 3 to 4 weeks. Your creatine stores drop back to baseline and your creatinine goes with them, so a standard creatinine and eGFR will read true. It works, it costs nothing, and most people don't want to do it.
Option two: keep taking it and ask for Cystatin C. Cystatin C is produced by cells throughout your body at a steady rate and it isn't affected by creatine, by how much muscle you carry, or by a high-protein diet. It answers the same question without the artefact.
Either way, there are three things worth doing in the day or two before any kidney test, whether you supplement or not, because all of them can nudge creatinine upwards on their own: skip the heavy protein meal, don't train hard, and turn up properly hydrated rather than dehydrated.
And tell whoever ordered the test. This is the single most useful thing in the article. A doctor looking at a raised creatinine in a healthy 30 year old who lifts weights will reach a very different conclusion if they know about the supplement than if they don't, and the difference between those two conclusions can be a referral, a repeat test and several weeks of worry.
Which kidney test should I ask for?
Depends whether you're supplementing and what you're trying to find out.
| Test | Price | Affected by creatine? | Use it when |
|---|---|---|---|
| Creatinine with eGFR | R70 | Yes, substantially | You're not supplementing, or you've stopped for 3 to 4 weeks. The standard first-line test. |
| Cystatin C | R694 | No | You take creatine and want an accurate reading without stopping. Also useful if you carry a lot of muscle. |
| U&E with creatinine | R380 | Partly, the creatinine portion | You want the wider picture: urea, sodium, potassium and creatinine together. |
| Albumin to creatinine ratio | R316 | Not meaningfully | You're looking for early kidney damage rather than filtration rate. Urine sample. |
The pairing most people supplementing should think about is the R70 creatinine alongside the R694 Cystatin C. If both come back normal, you've got your answer and no ambiguity. If creatinine is up and Cystatin C is normal, that's the pattern this whole article describes, and it's the reassuring one. If both are off, that's a genuine finding and one to take to a doctor.
Cystatin C
R694The kidney marker creatine doesn't touch. It's produced at a steady rate by cells throughout the body, so it isn't thrown off by supplements, muscle mass or a high-protein diet, which makes it the sensible choice if you lift and supplement and want a reading you can trust.
Answers: how well are my kidneys actually filtering?
Sample: yellow-top blood tube, walk in at any branch.
Creatinine with eGFR
R70The standard first-line kidney test, and the cheapest way to get a baseline. Just remember what it's measuring: if you're supplementing, the number will be raised and the eGFR will read low, and that's expected rather than worrying.
Answers: what's my creatinine, and what does the standard equation make of it?
Best paired with: Cystatin C, if you take creatine.
Creatinine clearance on a urine sample is R285, and there's a full urea and electrolytes panel at R380. Every test and price is on the full test list. Prices are 2026 cash rates including VAT and may change; in-store pricing applies. Payments over R1,200 can be split into 4 interest-free instalments.
Basically
Creatine doesn't appear to hurt healthy kidneys, but it does make the standard kidney test read as though it might have, which is why so many people who lift end up with a worrying result and no explanation for it.
If you're supplementing and you want to know where your kidneys really stand, either stop for a month before testing or spend the extra on Cystatin C, and tell whoever ordered the test what you're taking. And if you've got actual symptoms rather than just a number you don't like, see a doctor instead of reading about supplements.
Get a number you can actually trust
Cystatin C isn't affected by creatine, muscle mass or protein intake. No doctor's referral, no appointment, results in 2 to 5 working days.
Frequently Asked Questions
Does creatine damage your kidneys?
On the controlled evidence available, no, not in healthy adults taking recommended doses of 3 to 5g a day. Clinical trials with controlled designs have not found that creatine impairs kidney function, and studies that assessed kidney function using markers other than creatinine found it safe. The evidence in people who already have kidney disease is thin, because they're usually excluded from these studies, so anyone with known kidney disease should speak to a doctor before starting.
Why does creatine raise creatinine on a blood test?
Because creatinine is what creatine breaks down into once your body has used it. A standard kidney test measures the creatinine sitting in your blood and assumes a higher level means your kidneys are clearing less. Supplementing raises your creatine stores, so you produce more creatinine to clear, and the level rises by roughly 10 to 30% without your kidneys having changed.
Will creatine make my eGFR look low?
Yes, because eGFR is calculated from creatinine rather than measured directly. In the worked example used in the literature, a creatinine rise from 88 to 115 µmol/L drops eGFR from about 100 to about 76, which is a 24% apparent fall and enough to land in a band many laboratory reports flag as mildly decreased. The actual filtration rate hasn't changed.
Do I need to drink extra water when taking creatine?
Not as much as you've probably been told. A systematic review with meta-analysis in the Journal of Athletic Training found creatine did not reduce total body water as a proportion of body mass and did not impair thermoregulation during exercise in the heat, and the International Society of Sports Nutrition's position stand says there's no evidence creatine causes dehydration or cramping. One review found creatine users actually had less cramping, heat illness and dehydration than non-users. Creatine does raise your total body water, held inside your muscle cells, so drink normally and sensibly. What does matter is test day: being dehydrated raises creatinine on its own, which stacks on top of the rise creatine has already caused.
Should I stop creatine before a blood test?
If you want a standard creatinine and eGFR to read accurately, stop for 3 to 4 weeks beforehand. If you'd rather not interrupt your supplementing, ask for Cystatin C instead, since creatine doesn't affect it. Either way, in the day or two before any kidney test it helps to avoid a heavy protein meal, avoid training hard, and arrive properly hydrated, because all three can raise creatinine on their own.
What is Cystatin C and why is it better for creatine users?
Cystatin C is a protein produced at a steady rate by cells throughout your body and cleared by your kidneys, so it can be used to estimate filtration the same way creatinine is. The difference is that it isn't affected by creatine supplementation, by how much muscle you carry, or by a high-protein diet, which is exactly what makes creatinine unreliable in people who lift and supplement. At Epicentre it's R694 on a yellow-top blood tube, with no doctor's referral needed.
How much does a kidney function test cost in South Africa?
At Epicentre, creatinine with eGFR is R70, urea is R70, a full urea and electrolytes panel with creatinine is R380, creatinine clearance on a urine sample is R285, an albumin to creatinine ratio is R316 and Cystatin C is R694. No doctor's referral is needed if you're paying cash, and results come back in 2 to 5 working days.
Is creatine safe for women?
The kidney question is the same regardless of sex: creatine raises creatinine because of how it's metabolised, not because of anything to do with who's taking it, and the controlled evidence in healthy adults doesn't show kidney harm. One thing worth knowing is that the standard eGFR equation already adjusts for sex, so a woman on creatine will see the same kind of artefact and should handle it the same way, by stopping before testing or asking for Cystatin C.
What these words mean
- Creatine
- A compound stored in your muscles as a rapid energy reserve. Your body makes some of it and you get some from meat and fish. It's also the supplement.
- Creatinine
- The waste product left over when your body has finished with creatine. Your kidneys filter it out into your urine, which is why the level in your blood is used to judge how well they're working.
- eGFR
- Estimated glomerular filtration rate. Not measured directly but calculated from your creatinine, along with your age and sex, to estimate how much blood your kidneys are filtering per minute.
- Cystatin C
- A protein made at a steady rate by cells throughout your body and cleared by your kidneys. Used to estimate filtration like creatinine, but unaffected by creatine, muscle mass or protein intake.
- Albumin to creatinine ratio
- A urine test that looks for protein leaking into your urine, which is a sign of kidney damage rather than a measure of filtration speed. Often abbreviated to ACR.
References
- Effect of creatine supplementation on kidney function: a systematic review and meta-analysis. 2025. PMID 41199218
- de Souza e Silva A, et al. Is it time for a requiem for creatine supplementation-induced kidney failure? A narrative review. Nutrients. Read it
- Kreider RB, et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. Journal of the International Society of Sports Nutrition 2017. Read it
- Inker LA, et al. Estimating glomerular filtration rate from serum creatinine and cystatin C. New England Journal of Medicine 2012;367(1):20-29.
- Lopez RM, Casa DJ, McDermott BP, Ganio MS, Armstrong LE, Maresh CM. Does creatine supplementation hinder exercise heat tolerance or hydration status? A systematic review with meta-analyses. Journal of Athletic Training 2009. PMID 19295968
- Antonio J, et al. Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show? Journal of the International Society of Sports Nutrition 2021. Read it
- Poortmans JR, Francaux M. Long-term oral creatine supplementation does not impair renal function in healthy athletes. Medicine and Science in Sports and Exercise 1999;31(8):1108-1110.
This article is general health information and not medical advice, and it isn't a recommendation to start or stop any supplement. Epicentre is a diagnostic laboratory: we test and we report, and we don't diagnose, prescribe or treat. If you have known kidney disease, speak to your doctor before taking creatine. If you have swelling, foamy urine, a marked drop in how much you're passing, or persistent nausea and confusion, see a doctor promptly rather than waiting for a test result.
