Creatine and the kidneys: is there a risk?
“Creatine is bad for your kidneys.” This is the number one concern, and it has a specific origin — a misunderstanding about a blood test. Here’s what 18 studies show, including a meta-analysis, controlled trials involving people at risk, and follow-ups lasting up to several years. And, finally, the limitations that nobody ever mentions.
Where does fear come from: a misinterpreted indicator
To assess kidney function, a laboratory measures the level of creatinine in the blood. This is a waste product produced naturally by the muscles, which the kidneys filter out. If it builds up, it is a sign that the kidneys may not be filtering properly.
However, creatine is actually converted into creatinine. Taking it therefore increases the amount produced — and causes the marker to rise, without the kidneys being affected in any way. This is exactly what a study from 2000 observed: the slight rise in creatinine levels was attributed to increased production, not to kidney dysfunction, and levels returned to normal six weeks after stopping the supplement.
The crux of the misunderstanding
A case report from 2010 illustrates this perfectly: in a young man with only one kidney, the actual measured glomerular filtration rate remained unchanged during supplementation, whilst the level of creatinine in the blood rose — falsely suggesting impaired function.
What studies show when we really measure
The most reliable studies do not rely solely on creatinine: they measure glomerular filtration rate using a tracer, or use cystatin C, a marker that is not affected by creatine.
| Population | Dosage and duration | What was measured | Result |
|---|---|---|---|
| Healthy Athletes (1999) | 10 months to 5 years | Creatinine, urea, albumin | No difference compared with the control group |
| University Footballers (2002) | 5 to 20 g/day — 2.9 years on average | Creatinine, urea, clearance | No difference |
| Sedentary men (2008) | ~10 g/day — 3 months | Cystatin C | No malfunction |
| People with type 2 diabetes (2011) | 12 weeks | Measured filtration (tracer) | Unchanged |
| Athletes on a high-protein diet (2013) | 20 g/day for 5 days, then 5 g/day — 12 weeks | Measured filtration | Unchanged |
| Postmenopausal women (2011) | 20 g/day for 1 week, then 5 g/day — 12 weeks | Measured filtration | Unchanged |
| Meta-analysis (2019) | 15 studies reviewed | Creatinine, urea | No significant changes |
The 2013 study is worth mentioning: this is precisely the situation that causes the most concern — bodybuilders who already consume a lot of protein and add creatine on top of that. Filtration, measured using a tracer, remained unchanged over 12 weeks.
Dosages and durations as reported in the studies cited below.
The position statement from the International Society of Sports Nutrition (2017) — the leading authority in the field — concludes that supplementation is safe and well tolerated, up to 30 g per day for 5 years, in populations ranging from infants to the elderly. By way of comparison, the standard effective dose is 3 to 5 g per day.
The limits, to be honest
It would be disingenuous to stop there. Three reservations emerge from this same body of literature:
| Reserve | What the studies say |
|---|---|
| Pre-existing kidney disease | Two reviews (2011, 2019) explicitly recommend caution and advise against high doses in cases of kidney disease or known risk factors. |
| A case of acute injury | A case report (2011) describes an 18-year-old man in good health who developed acute kidney failure, confirmed by biopsy, whilst taking the recommended dose. |
| Very long term | One review (2007) highlights the lack of data covering more than a few years, whilst another (2005) calls for further studies involving older people and those with kidney failure. |
How to interpret an isolated case
In practice
| Scenario | What the studies suggest |
|---|---|
| Healthy adult | No evidence of kidney damage, even over several years |
| High-protein diet | Measured filtration remained unchanged over 12 weeks |
| Type 2 diabetes | Measured filtration remained unchanged over 12 weeks |
| Known kidney disease | Explicit advice — speak to a doctor |
| Scheduled blood test | Please note if you are taking creatine: it can affect creatinine readings |
Dosage, proven benefits and study summaries: it’s all on the creatine fact sheet, along with the sources.
See the creatine fact sheetEvery statement in this article is based on the studies listed below, summarised solely on the basis of their abstracts. This is for information purposes only: it is not a substitute for medical advice, particularly in the case of a known kidney condition.
The studies cited
- International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. (2017)
- Acute creatine loading increases fat-free mass, but does not affect blood pressure, plasma creatinine, or CK activity in men and women. (2000)
- Long-term oral creatine supplementation does not impair renal function in healthy athletes. (1999)
- Creatine supplementation does not impair kidney function in type 2 diabetic patients: a randomized, double-blind, placebo-controlled, clinical trial. (2011)
- Beyond sports: Efficacy and safety of creatine supplementation in pathological or paraphysiological conditions of brain and muscle. (2019)
- Dietary creatine supplementation does not affect some haematological indices, or indices of muscle damage and hepatic and renal function. (2000)
- Studies on the safety of creatine supplementation. (2011)
- Effects of creatine supplementation on renal function: a randomized, double-blind, placebo-controlled clinical trial. (2008)
- Effects of Creatine Supplementation on Renal Function: A Systematic Review and Meta-Analysis. (2019)
- Safety of creatine supplementation. (2007)
- The effect of creatine intake on renal function. (2005)
- Effects of long-term creatine supplementation on liver and kidney functions in American college football players. (2002)
- Does long-term creatine supplementation impair kidney function in resistance-trained individuals consuming a high-protein diet? (2013)
- Effect of short-term high-dose creatine supplementation on measured GFR in a young man with a single kidney. (2010)
- Effect of creatine supplementation on measured glomerular filtration rate in postmenopausal women. (2011)
- The effects of the recommended dose of creatine monohydrate on kidney function. (2011)
- Effects of creatine supplementation on renal function. (2004)
- Efficacy and safety of creatine supplementation in childhood-onset systemic lupus erythematosus: a randomized, double-blind, placebo-controlled, crossover trial. (2014)