Creatine is not bad for your kidneys, per Antonio's 2021 review of over 500 published studies

Why everyone thinks creatine wrecks your kidneys

Elevated creatinine on a blood test doesn't mean your kidneys are failing. That's the whole myth, in one sentence.

Here's the mix-up. Doctors check kidney function by measuring creatinine — a waste product your kidneys filter out of your blood. When you supplement with creatine, your muscles naturally produce more creatinine as a byproduct of normal turnover. So your creatinine number climbs on the lab report.

A doctor who doesn't know you're taking creatine sees that number rise and flags a possible kidney problem. But the kidneys aren't struggling — they're just processing more of a substance your own muscles are making. An evidence review — a paper that pools together the existing research to answer one specific question — has pointed to this exact mix-up as one of the reasons the myth won't die (Antonio et al., 2021).

The people running controlled studies wanted a real answer, not a guess based on one lab value. So they measured everything.

A controlled study checked 41 blood and urine markers — nothing moved

One study didn't just check creatinine. It ran an RCT — people randomly split into a creatine group and a placebo group, then compared head-to-head — and tracked 41 separate blood and urine markers (Almeida et al., 2020).

Eighteen men who trained three times a week took 0.3 g of creatine monohydrate per kilogram of bodyweight per day — a loading dose, meant to saturate your muscles with creatine fast — for seven days. A matched group took a sugar-based placebo instead. Blood and urine were drawn before supplementation and again 30 days later.

The results: body weight went up, performance went up, exactly as expected from creatine. Kidney function markers didn't move. Liver function didn't move. Red and white blood cell counts, blood lipids, and metabolic markers didn't move either (Almeida et al., 2020).

All 41 markers came back clean. Not "probably fine" — actually measured, and unchanged.

It's not one lucky study — the whole field agrees

Creatine has been the subject of over 500 peer-reviewed publications. A 2021 evidence review set out to answer the kidney question directly by weighing that entire body of research (Antonio et al., 2021).

Their conclusion: creatine supplementation is "relatively well tolerated," especially at the doses people actually use — 3 to 5 grams a day, or 0.1 g per kilogram of bodyweight per day (Antonio et al., 2021). That's the maintenance range most lifters land on, well below the loading dose tested for safety in the Almeida study above.

That review lists twelve separate myths and open questions about creatine — kidney safety among them — and works through the evidence on each one (Antonio et al., 2021). The pattern holds across all of it: no sign of harm at normal doses, just persistent worry that outlived the data. is creatine bad for your heart covers the same pattern for another organ people worry about needlessly.

Creatine has been studied in more than 500 published papers — and none of them found kidney damage in a healthy adult.

— Antonio et al. (2021). Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show? Journal of the International Society of Sports Nutrition.

The one group that actually needs to be careful

Healthy kidneys handle creatine fine. That word matters: healthy.

A 2025 review of the most common creatine safety concerns found no adverse effect on kidney function in people with normal kidney health — but it draws a clear line for two groups where the research simply isn't there yet: people with existing kidney conditions, and pregnant women (Longobardi et al., 2025). That's not "it's dangerous for them" — there just isn't enough controlled data on those groups to say either way, so caution is the honest answer.

The same review knocked out two more common fears. Creatine doesn't cause dehydration or muscle cramps during exercise — controlled studies show no effect on hydration or the body's ability to regulate its temperature, and creatine may actually reduce cramping (Longobardi et al., 2025). The theoretical cancer-risk concern, based on how creatine breaks down in the body, also has no supporting evidence in real-world research (Longobardi et al., 2025).

The one side effect worth knowing about is milder: stomach upset, and it's dose-dependent — more likely from a large single dose than from spreading it out (Longobardi et al., 2025).

If you have healthy kidneys, the evidence says don't worry. If you already have kidney disease, that's a conversation for your doctor — not a warning on the label.

— Longobardi et al. (2025). A short review of the most common safety concerns regarding creatine ingestion. Frontiers in Nutrition.

How to actually take it

None of this changes with how you take it — dose and consistency are what the safety research is built around, not the supplement itself.

Stick to 3–5 grams of creatine monohydrate a day (Antonio et al., 2021). If you want faster muscle saturation, the loading protocol tested for safety above was 0.3 g/kg/day for about a week before dropping to that maintenance range (Almeida et al., 2020) — split a bigger loading dose across 2–3 servings through the day rather than one sitting, since that's what keeps stomach upset from showing up (Longobardi et al., 2025).

Timing relative to your workout doesn't factor into kidney safety at all — this is about total daily amount, not the minute you take it. And you don't need extra water beyond your normal training intake; creatine doesn't dehydrate you the way the old myth claims (Longobardi et al., 2025) water intake calculator.

If you're curious whether any of this changes depending on who's taking it, creatine for women breaks down what a 2-year randomized trial of 237 women actually found.