Does Creatine Damage Your Kidneys? What the Evidence Actually Shows

Creatine does not damage healthy kidneys. That's been tested directly, repeatedly, with real measurements of kidney filtration rather than proxies — and it keeps coming back clean.

But there's a twist that explains why the myth won't die, and why some people genuinely do get a worrying phone call from their doctor after starting creatine. It has nothing to do with kidney damage and everything to do with one letter.

The Short Answer

The International Society of Sports Nutrition's position stand states there is "no compelling evidence that creatine supplementation negatively affects renal function in healthy or clinical populations."¹ The NIH's Office of Dietary Supplements agrees creatine "is safe for healthy adults to take for several weeks or months" and "also seems safe for long-term use over several years," with weight gain from water retention as the usual side effect.⁴

Now the twist. Creatine raises serum creatinine — the exact blood marker labs use to estimate how well your kidneys are filtering. Your lab report can look worse while your kidneys work exactly as well as before.³ That misread is the real harm creatine causes, and it lands on a lab printout, not on your nephrons.

Creatine vs. Creatinine: The One-Letter Difference That Causes All the Panic

Almost every kidney scare traces back to conflating two words that differ by two letters.

What creatinine actually is

Creatinine is a waste product. Creatine sitting in your muscle spontaneously converts to creatinine; your kidneys filter it out and you pee it out.³ Because that production rate is normally stable, doctors use blood creatinine as a cheap stand-in for kidney filtration. Creatinine goes up, the assumption is that filtration went down.

That assumption has a hidden premise: that the amount of creatinine you produce hasn't changed.

Why supplementing raises it

Take creatine and you break the premise. More creatine in your muscle means more creatinine produced per day. Your kidneys filter the extra without trouble, but blood levels sit slightly higher — because the supply went up, not because the drain got blocked.³

That matters, because eGFR is calculated from serum creatinine. Feed a mildly elevated creatinine into the formula and it hands back a mildly reduced eGFR — a number that says "your kidneys are filtering worse" when nothing about them has changed. Reviewers of this literature put it directly: kidney function stays preserved, as shown by markers that aren't tied to creatine metabolism — measured GFR, cystatin C, proteinuria, albuminuria — even when creatinine drifts up.³

How big is the drift? A 2025 meta-analysis in BMC Nephrology found "a small but statistically significant increase in serum creatinine" (p = 0.03), with no significant change in GFR.² Clinically trivial in a healthy person — but big enough to trip a lab's reference range and start a conversation you didn't plan on.

The cleanest illustration is a case report of a young man with one kidney: after 35 days of creatine, his serum creatinine rose from 1.03 to 1.27 mg/dL while his measured GFR stayed flat (81.6 → 82.0 mL/min/1.73 m²) — an elevation the authors said was "falsely suggesting kidney function impairment."⁸ Two markers, opposite stories. One of them was wrong.

What to do about it

1. Tell whoever ordered the bloodwork that you take creatine, and at what dose. One sentence reframes an out-of-range creatinine from "possible kidney disease" to "expected and explained."
2. Ask about cystatin C. It's a filtration marker that isn't produced by creatine metabolism, which makes it the sensible tiebreaker when a creatinine-based number looks off in a supplement user.³ Whether to order it is your clinician's call.
3. Don't stop creatine before a test on your own to "clean up" your numbers. If your doctor wants a reading without the supplement in the picture, they'll tell you.

What the Long-Term Evidence Actually Shows in Healthy Adults

The controlled trials

Poortmans and Francaux compared people who had been taking oral creatine for 10 months to 5 years against controls, measuring creatinine, urea, and albumin clearances. No differences — filtration rate, tubular reabsorption, and membrane permeability were normal in both groups. Their conclusion: "Neither short-term, medium-term, nor long-term oral creatine supplements induce detrimental effects on the kidney of healthy individuals."⁵

Lugaresi and colleagues then stress-tested it: a 12-week randomized, double-blind, placebo-controlled trial in resistance-trained people already eating a high-protein diet (≥1.2 g/kg/day) — the exact "double load on the kidneys" scenario people fear. Crucially, they measured GFR properly, with 51Cr-EDTA clearance rather than a creatinine-derived estimate. GFR didn't budge (creatine: 101.4 → 108.8 mL/min/1.73 m²; placebo: 103.3 → 106.7; p = 0.64), and creatinine clearance, urea, electrolytes, proteinuria, and albuminuria "remained virtually unchanged."⁶

That's the design that matters. If creatine were quietly damaging kidneys, a real filtration measurement in the highest-risk healthy group is where it would show up.

The 2025 meta-analysis

The most recent synthesis is Naeini et al. in BMC Nephrology (2025): 21 studies systematically reviewed, 12 pooled, roughly 440 participants in the creatinine analysis.² It lines up with everything above. The creatinine bump is "likely due to metabolic turnover rather than renal impairment," with "no significant changes... in GFR, suggesting preserved kidney function."²

Two caveats we're not going to bury:

• The authors call the creatinine rise "transient," but their own subgroup analysis is messier. It was significant in trials of ≤1 week, not significant at 1–12 weeks, then significant again past 12 weeks — which they read as "a possible delayed but meaningful elevation in serum creatinine over extended supplementation periods."² Plainly: the marker may stay up as long as you keep supplementing. GFR still didn't move, so it's still a marker story — but "transient" oversells it.
• The evidence base is thinner than the confidence around it. The authors state that "most included studies were of short to moderate duration; long-term safety data beyond one year remain sparse," in a literature of small, mostly single-center trials.² The participants were healthy adults, athletes, postmenopausal women, people with type 2 diabetes — not people with chronic kidney disease.

Where the scare came from

A handful of case reports — individual patients whose kidney function declined while they happened to be taking creatine — plus animal studies showing renal changes in supplemented rats.³

A case report is a story about one person. It can flag a hypothesis; it can't establish that A caused B, because there's no control, no randomization, and usually no clean baseline. The narrative review that dug into these reports found the problems you'd expect: retrospective self-reporting, missing baseline data, and confounders — pre-existing kidney disease, nephrotoxic medications, anabolic steroids, extreme training.³ On the animal side, it notes conflicting results and warns that "data obtained in animals often cannot be extrapolated to humans."³

That's no sneer at the clinicians who published them; flagging a worrying case is how medicine is supposed to work. The point is what happened next — the hypothesis got tested properly, and it didn't hold up.

The ISSN Position: What It Does and Doesn't Say

What it says: creatine monohydrate is safe in healthy individuals at recommended doses — "no compelling scientific evidence that the short- or long-term use of creatine monohydrate (up to 30 g/day for 5 years) has any detrimental effects on otherwise healthy individuals."¹

What it doesn't say: that it's cleared for everyone. The caveat is in the source itself — the position stand acknowledges the suggestion that "individuals with pre-existing renal disease consult with their physician prior to creatine supplementation in an abundance of caution."¹ That line is part of the position, not a critic's addition to it.

One disclosure: the ISSN receives support from companies that manufacture and sell creatine, and several authors of these papers declare industry ties, including advisory roles with a creatine manufacturer.⁷ That doesn't make them wrong — their conclusions match independent trials and a meta-analysis in a nephrology journal. But you should know who's speaking.

The Honest Limits (Where We Genuinely Don't Know)

Pre-existing chronic kidney disease

This is the real gap. Every reassuring number on this page came from a kidney that started out working, and even in those healthy populations the authors flag that data beyond a year is sparse.² Creatine is being studied in kidney patients, but "under investigation" is a research question, not a recommendation, and we won't dress it up as one.

One kidney

The only prospective human data is a single case: a 20-year-old man post-nephrectomy, mildly reduced GFR, on a high-protein diet (2.8 g/kg/day). He took 20 g/day for 5 days, then 5 g/day for 30 days. Measured GFR (51Cr-EDTA), proteinuria, and electrolytes were unchanged; serum creatinine rose and falsely implied impairment.⁸

Reassuring — and n=1. One person, 35 days, no control group. It can't generalize to you. If you have one kidney, that's a reason for your nephrologist to be less alarmed, not a reason to skip asking them.

Kidney stones

No study has linked creatine to kidney stones. The only human data is a 2022 case report: an athlete with a history of stones took creatine for two months and had no recurrence 14 months later.⁹ Its authors note that before them, "no previous study has investigated its effects on kidney stones in humans."⁹ No signal — in a nearly empty literature. Weak reassurance, and we'll call it that.

Everything else with no data

These groups aren't "at risk." They're unstudied, which deserves a different answer than false confidence: pregnancy and breastfeeding, anyone under 18, anyone on medication that stresses the kidneys or requires kidney-function monitoring (long-term high-dose NSAIDs, certain diuretics), and anyone whose kidney function is already being watched — the creatinine confound alone is reason to loop in your clinician.

How to Keep Your Kidneys Out of It (Practical)

Four things, none of them exotic.

1. Take 3–5 g/day and skip the mega-doses. The maintenance dose saturates your muscles in about three to four weeks with no loading phase at all.¹ Once you're saturated, more buys you nothing. Full dosing logic: how much creatine to take.

2. Hydrate normally, not heroically. Chugging gallons doesn't protect your kidneys from a supplement that isn't attacking them. Drink to thirst. (The related fear that creatine causes dehydration and cramping has been tested and didn't hold up.⁷)

3. Buy a third-party-tested product. The underrated risk isn't the creatine — it's what else ends up in the tub. Creatine is chemically synthesized, and purity depends on the manufacturer. NSF Certified for Sport and Informed Sport verify that what's on the label is what's in the powder. For a shortlist ranked on published third-party certification, see our picks for creatine monohydrate. (We may earn a commission from links on that page, at no extra cost to you; it never affects the ranking.)

4. Tell your doctor you supplement. Especially before bloodwork. This prevents the only kidney-related problem creatine reliably causes.

Frequently Asked Questions

Does creatine damage your kidneys?

Not in healthy people. The ISSN found no compelling evidence that creatine negatively affects renal function,¹ athletes supplementing 10 months to 5 years showed no impairment,⁵ and a 12-week trial in people on a high-protein diet found no change in measured GFR.⁶ If your kidneys are already impaired, that evidence doesn't cover you.

Does creatine raise creatinine levels?

Yes — a small but statistically significant rise, with no matching change in GFR.² Creatine converts to creatinine, so you produce more of it. Because eGFR is calculated from creatinine, that benign rise can make an estimated kidney-function number look worse than reality.³

Should I tell my doctor I take creatine before a blood test?

Yes — it's the most useful thing on this page. Without that sentence, an expected creatinine elevation can be read as declining kidney function.³ If the number still looks off, cystatin C isn't affected by creatine metabolism and can act as a tiebreaker.³ Don't stop creatine on your own to tidy up a result.

Can I take creatine if I have kidney disease or only one kidney?

Ask your nephrologist. The reassuring data comes from healthy kidneys, and the ISSN advises people with pre-existing renal disease to consult a physician first.¹ For a single kidney, the only prospective human data is one case report — reassuring, but n=1 with no control group.⁸

Does creatine cause kidney stones?

No evidence links them. The only human data is a 2022 case report: an athlete with a history of stones supplemented for two months, with no recurrence over 14 months.⁹ No signal — in a nearly empty literature.

How much creatine is safe for your kidneys?

3–5 g/day has no established kidney risk in healthy adults, and the ISSN found no detrimental effects up to 30 g/day for 5 years in healthy people.¹ Past saturation, more does nothing for you.¹

The Bottom Line

The kidney fear survives on a misunderstanding, not a finding. When researchers stop using creatinine as a proxy and actually measure filtration, creatine's effect on healthy kidneys keeps coming back as nothing — in trials running 10 months to 5 years, and in the 2025 meta-analysis.²⁵⁶

What's real is the lab-value problem: your creatinine runs a little higher, your creatinine-derived eGFR reads a little lower, and if nobody knows you supplement, that can look like a kidney going bad. Tell your doctor. That's the whole fix.

And keep the scope honest. Every study above was run on kidneys that worked. If yours don't, this evidence base has nothing to say about you, and the right move is a nephrologist — not another article. This one is educational and not medical advice.

For the rest of the safety picture, work through hair loss, acne, bloating, weight gain, and creatine with alcohol. New to all this? Start with what creatine is and how it works.