Is Creatine Bad for Your Kidneys? What Science Says

Short answer: No - for healthy people taking normal doses, creatine does not damage your kidneys. The myth largely comes from a misunderstanding of a single blood test. Creatine naturally turns into a waste product called creatinine, which is the exact marker doctors use to estimate kidney function - so supplementing can nudge that number upward without any actual change in how your kidneys are working. When researchers measure kidney function directly, it stays normal, including in a 2025 review that pooled 21 studies.

After the hair-loss myth, "creatine wrecks your kidneys" is probably the most common reason people talk themselves out of taking it. It sounds plausible - the kidneys filter waste, creatine is processed by the body, so surely loading up on it puts them under strain? It's a reasonable worry, and it deserves a proper answer rather than a hand-wave. So let's look at exactly where the fear came from, why a blood test is at the centre of the confusion, and what happens when scientists measure kidney function the right way.

Where the kidney worry comes from

The concern has a few roots. There are a handful of decades-old case reports of people with kidney problems who also happened to take creatine - but these involved pre-existing conditions or other confounding factors, and a few anecdotes can't establish cause and effect. The worry also gets tangled up with the separate (and also overstated) myth that high-protein diets damage kidneys, since the two often go together in gym culture.

But the single biggest driver of the myth is a genuine, measurable thing that looks alarming if you don't know what's behind it: creatine supplementation can raise the level of creatinine in your blood. And creatinine is the number doctors look at to judge how well your kidneys are working. Understanding that one link dissolves most of the fear.

The creatinine mix-up at the heart of the myth

Here's the chain of events. The creatine stored in your muscles is constantly, spontaneously broken down into a waste product called creatinine - roughly 1–2% of it every day. Your kidneys filter that creatinine out of your blood and into your urine. Because the amount of creatinine in your blood normally tracks with how efficiently your kidneys are filtering, doctors measure serum creatinine to estimate your glomerular filtration rate (GFR) - the standard yardstick of kidney function.

Now add a creatine supplement. You've increased the total amount of creatine in your body, so naturally a bit more creatinine is produced. More creatinine in the blood means a higher serum creatinine reading - and, on paper, a slightly "worse"-looking estimated GFR. But nothing has actually changed about your kidneys. They're filtering exactly as well as before; there's just more creatinine passing through because you ate more creatine. It's a bit like a factory's output going up because you delivered more raw material - not because the machinery is breaking down.

This is the crux of the whole myth: a rise in serum creatinine after starting creatine is an expected by-product of supplementation, not a sign of kidney damage. To know what your kidneys are really doing, you have to measure filtration directly - and that's exactly what the research has done.

What the research actually shows

When studies use direct or more accurate measures of kidney function rather than relying on the creatinine estimate, the picture is consistent and reassuring.

The 2025 systematic review and meta-analysis is the most comprehensive look at this question to date. Pooling 21 studies, it found that creatine supplementation is associated with only a modest rise in serum creatinine - exactly the by-product effect described above - while glomerular filtration rate, the best overall indicator of kidney health, was not adversely affected.^[1] Its authors specifically caution clinicians to interpret a raised creatinine reading in the context of supplementation rather than mistaking it for impaired function.

This sits on top of the International Society of Sports Nutrition's position stand, which reviewed the broader safety literature and concluded there is no compelling evidence that creatine harms kidney function in healthy individuals at recommended doses.^[3]

"But I lift heavy and eat loads of protein"

This is the most common follow-up, and it's a fair one - the people most drawn to creatine are often the same people eating high-protein diets and training hard, and there's a lingering belief that the combination piles pressure on the kidneys.

One study was designed to test exactly that scenario. Lugaresi and colleagues took resistance-trained men who were already eating a high-protein diet (at least 1.2 g of protein per kilogram of bodyweight per day), gave them creatine for 12 weeks, and measured their kidney function using ⁵¹Cr-EDTA clearance - a gold-standard, direct measurement of GFR, far more precise than the creatinine estimate.^[2] The result: no significant change in filtration rate, and other markers including urea, electrolytes, and protein in the urine stayed essentially unchanged. Creatine plus heavy lifting plus a high-protein diet did not harm the kidneys of healthy people.

What about taking it for years?

Long-term use is well studied too. Trials and reviews following healthy people on creatine for months to years have not found cumulative kidney damage at standard doses.^[3][4] In fact, creatine's safety profile is solid enough that researchers are now investigating it in clinical populations, which tells you how far the evidence has moved from the old "it's hard on your kidneys" assumption.

Who should still check with a doctor first

The reassuring evidence above applies to healthy people. If you already have chronic kidney disease, reduced kidney function, a single kidney, or risk factors such as poorly controlled diabetes or high blood pressure, that's a different situation - findings in healthy people don't automatically transfer to compromised kidneys. It doesn't mean creatine is necessarily off the table, but it's a conversation to have with your GP or a kidney specialist who knows your history, rather than a decision to make from a blog. When in doubt, ask your doctor.

A practical tip if you get blood tests

Here's something genuinely useful that most articles skip. Because creatine raises your serum creatinine, it's worth mentioning to your GP or the lab that you take it before a routine blood test. Otherwise a slightly elevated creatinine result can be misread as a kidney problem, potentially triggering unnecessary worry or follow-up tests. If a more precise reading is ever needed, there's an alternative marker called cystatin C that isn't affected by creatine supplementation. A quick heads-up to your doctor saves a lot of confusion.

The bottom line

The "creatine ruins your kidneys" myth is built almost entirely on a lab-test misunderstanding. Creatine raises the blood marker doctors use to estimate kidney function, but when researchers measure that function directly - even in lifters eating high-protein diets, even over the long term - it stays normal. For healthy people at sensible doses, creatine monohydrate is one of the most thoroughly safety-tested supplements available, and your kidneys are not the reason to avoid it.

If a pre-existing kidney condition is in the picture, check with your doctor first. For everyone else, you can put this worry where it belongs - with the myths.

Frequently asked questions

Does creatine damage your kidneys?

There's no good evidence that it does in healthy people at recommended doses. The largest review to date - a 2025 meta-analysis of 21 studies - found no adverse effect on glomerular filtration rate, the gold-standard measure of kidney function.

Why did my blood test show high creatinine after starting creatine?

Because creatine is converted into creatinine in the body, supplementing adds more of it to your blood. That raises the reading without your kidneys actually working any worse. Tell your doctor you take creatine so the result is interpreted correctly.

Is creatine safe with a high-protein diet?

Yes. A 12-week study on resistance-trained men eating high-protein diets used a gold-standard direct measurement of kidney function and found no change while taking creatine.

Is creatine safe to take long term?

Yes. Studies following healthy people for months to years at standard doses have found no cumulative kidney harm.

Can I take creatine if I have a kidney condition?

If you have existing kidney disease, reduced function, or related risk factors, speak with your GP or a kidney specialist first. The reassuring research is in healthy people and doesn't automatically apply to compromised kidneys.

References

1. Naeini F, et al. Effect of creatine supplementation on kidney function: a systematic review and meta-analysis. BMC Nephrol. 2025;26:622. doi:10.1186/s12882-025-04558-6
2. Lugaresi R, Leme M, de Salles Painelli V, et al. Does long-term creatine supplementation impair kidney function in resistance-trained individuals consuming a high-protein diet? J Int Soc Sports Nutr. 2013;10:26. doi:10.1186/1550-2783-10-26
3. 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. doi:10.1186/s12970-017-0173-z
4. Antonio J, Candow DG, Forbes SC, et al. Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show? J Int Soc Sports Nutr. 2021;18(1):13. doi:10.1186/s12970-021-00412-w

This article is general information, not medical advice. If you have a kidney condition or concerns about your kidney health, consult a qualified healthcare professional.