Study analysis · BMC Nephrology · 2025
Creatine is safe for your kidneys—new meta-analysis shows only a tiny, harmless bump in creatinine, not damage.
Creatine supplements don't hurt kidney function, even though they slightly raise a blood marker called creatinine.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
In simple terms
Think of this as a big report that combines many smaller studies about creatine and kidney health. It found that taking creatine slightly raises a substance in your blood called creatinine, but it didn't see any harm to how well your kidneys filter blood. But because the studies were different types and some were not very strong, we can't say for sure that creatine causes those changes—just that they happen together.
What’s the bottom line?
Creatine is a supplement people take to build muscle. Some worry it might damage kidneys because it raises a blood marker called creatinine. But creatinine is a waste product from muscles, and if you take creatine, you make more of it. This study looks at many past studies and finds that while creatinine levels go up a little, a better test of kidney health (called GFR) doesn't change. That means creatine probably doesn't harm kidneys.
How strong is this study?
This report is like a mix of many studies, some better than others. It looked at 21 studies and combined their results, which is nice. But many of these studies were small, short, and not all were randomized. That means the results might be a bit shaky, so we should be careful before saying creatine is completely safe for everyone.
40 / 100
- COI disclosure+40/40
- Data availabilitydata not shared
- Code availabilitycode not shared
0 / 100
- Randomizationnot randomized
- Blindingblinding unclear
- Control groupno control group
- Sample sizeno sample size reported
- Follow-upno follow-up reported
100 / 100
77 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervals+15/15
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 547 / 100
Probability of being correct
Systematic reviews and meta-analyses of cohort studies. They sit above a single cohort study but below a single randomized trial, because the underlying evidence is still observational.
This design cannot establish causation — the findings describe an association, not a cause. This systematic review and meta-analysis includes a mix of study designs (RCTs, cohort, case-control, and non-randomized trials). While RCTs could potentially establish causation, the pooling of both randomized and observational studies makes it impossible to attribute causality with confidence. The observed associations may be influenced by confounding and bias inherent in observational designs.
COI Unknown
Could not determine conflict of interest status
No conflict of interest statement is provided in the text. The presence of conflicts or funding cannot be determined from the available information.
The study text does not disclose author affiliations, funding sources, or any potential conflicts of interest. Without this information, it is impossible to assess the severity of any bias. The methods describe a standard systematic review process with independent reviewers, but no explicit safeguards against funder influence are mentioned.
Key takeaways
- 01
People taking creatine had a tiny increase in creatinine (0.07 units) compared to those not taking it.
- 02
But their kidney filtration rate (GFR) was the same.
- 03
The increase in creatinine was only noticeable in the first week and after 3 months, not in between.
- 04
The rise in creatinine is very small and unlikely to matter for healthy people.
- 05
Doctors usually look at GFR, which didn't change, so creatine seems safe.
Surprising findings
- Despite a statistically significant increase in serum creatinine, GFR—the most accurate measure of kidney function—remains completely unchanged.Commonly, elevated creatinine alarms doctors, but here it's a false alarm because the increase is due to increased creatine breakdown, not reduced kidney function.
- The effect on creatinine disappears during the middle of supplementation (1-12 weeks), but reappears after 12 weeks.We might expect a consistent effect, but the body appears to adapt temporarily and then adjust again, showing a complex physiological response.
- Only 12 studies out of 21 could be meta-analyzed for creatinine, and only 5 for GFR, revealing a lack of robust research in this area.Despite creatine being heavily studied, kidney outcomes are often poorly reported, limiting meta-analytic power.
Practical takeaways
If you're taking creatine and get a blood test showing elevated creatinine, don't panic—ask your doctor to check GFR as well.
Always consult with a healthcare professional, especially if you have pre-existing kidney conditions.
high confidenceFor athletes and fitness enthusiasts, creatine at standard doses (3-5g/day) is safe for kidney function based on this meta-analysis.
Most studies were short-term; long-term data (>1 year) are limited, so periodic monitoring is still advisable.
medium confidenceWhen assessing kidney health in creatine users, healthcare providers should rely on GFR measurements rather than serum creatinine alone.
This is a key takeaway for clinicians, but implementation may require changing standard lab panels.
high confidenceWhy this study matters
The Creatinine Confusion
Creatine supplementation increases serum creatinine by a tiny amount (0.07 µmol/L, 95% CI 0.01-0.12), which is statistically significant but clinically irrelevant. This rise is not a sign of kidney damage; it's just a byproduct of creatine metabolism. GFR—the real kidney function test—doesn't change at all.
Many people avoid creatine fearing kidney problems. This clears the air: your kidneys are fine, the marker is just a false alarm.
Time Matters: When Creatinine Spikes
The creatinine increase is only significant in the first week (MD=0.12 µmol/L) and after 12 weeks, but between 1-12 weeks it's not significantly different (MD=0.04). This suggests the body adapts mid-term, but long-term there's a slight elevation again.
It shows the body's dynamic response to creatine, and that long-term use might have a different effect, though still harmless.
The Real Test: GFR Doesn't Budge
Glomerular filtration rate (GFR), the gold standard for kidney function, showed no significant change after creatine supplementation (pooled from 5 studies, 69 creatine vs 74 control). This is strong evidence that creatine doesn't impair kidney filtration.
While creatinine is what you hear about, GFR is the actual measure of kidney health. This is the reassuring number.
Who Can Take Creatine?
The review included both healthy and clinical populations, and no adverse effects on GFR were found across all groups. Creatine appears safe for kidney function, even in some patient groups.
This expands the viable user base beyond just athletes to potentially include certain patient populations, though always with medical supervision.
Want the whole report?
Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Creatine is a supplement people take to build muscle. Some worry it might damage kidneys because it raises a blood marker called creatinine. But creatinine is a waste product from muscles, and if you take creatine, you make more of it. This study looks at many past studies and finds that while creatinine levels go up a little, a better test of kidney health (called GFR) doesn't change. That means creatine probably doesn't harm kidneys.
Research results
People taking creatine had a tiny increase in creatinine (0.07 units) compared to those not taking it. But their kidney filtration rate (GFR) was the same. The increase in creatinine was only noticeable in the first week and after 3 months, not in between.
What this means - more context
The rise in creatinine is very small and unlikely to matter for healthy people. Doctors usually look at GFR, which didn't change, so creatine seems safe.
To systematically review and meta-analyze the effects of creatine supplementation on kidney function, specifically serum creatinine and glomerular filtration rate (GFR).
Creatine supplementation is associated with a small but statistically significant increase in serum creatinine (MD 0.07 µmol/L, 95% CI 0.01–0.12), but no significant change in GFR. The creatinine increase is transient and duration-dependent, with significant effects at <1 week and >12 weeks, but not between 1–12 weeks. The authors conclude that the rise in creatinine reflects increased creatine metabolism rather than renal impairment, and that creatine is safe for kidney function in healthy and clinical populations at standard doses.
Methods Used
Systematic review and meta-analysis following PRISMA guidelines. Searched PubMed, Scopus, Web of Science, and Google Scholar for studies from January 2000 to March 2025. Included human studies of any design that assessed serum creatinine or GFR after oral creatine supplementation. Random-effects model used for meta-analysis, with subgroup analysis by supplementation duration.
Main Finding
Meta-analysis of 12 studies (177 creatine users, 263 controls) found a statistically significant increase in serum creatinine (MD = 0.07 µmol/L; 95% CI: 0.01–0.12; p=0.03). Subgroup analysis showed significant effects in studies ≤1 week (MD=0.12; 95% CI:0.03–0.21) and >12 weeks, but not 1–12 weeks. Meta-analysis of 5 studies (69 creatine, 74 controls) found no significant change in GFR.
Confidence Level
Moderate. Heterogeneity for creatinine was substantial (I²=69.73%), and risk of bias was rated 'some concern' in most studies. Publication bias was suggested by funnel plots but trim-and-fill analysis did not change results.
Study Flags
Red Flags
- •Substantial heterogeneity for creatinine outcomes
- •Risk of bias rated as 'some concern' in included studies
- •Potential publication bias suggested by funnel plots
Surprising Findings
Despite a statistically significant increase in serum creatinine, GFR—the most accurate measure of kidney function—remains completely unchanged.
Commonly, elevated creatinine alarms doctors, but here it's a false alarm because the increase is due to increased creatine breakdown, not reduced kidney function.
Practical Takeaways
If you're taking creatine and get a blood test showing elevated creatinine, don't panic—ask your doctor to check GFR as well.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 547 / 100
Probability of being correct
Systematic reviews and meta-analyses of cohort studies. They sit above a single cohort study but below a single randomized trial, because the underlying evidence is still observational.
Human Meta-Analysis
Subject
Moderate probability
on the GRADE evidence scale
Think of this as a big report that combines many smaller studies about creatine and kidney health. It found that taking creatine slightly raises a substance in your blood called creatinine, but it didn't see any harm to how well your kidneys filter blood. But because the studies were different types and some were not very strong, we can't say for sure that creatine causes those changes—just that they happen together.
Strengths
- Comprehensive literature search across multiple databases (PubMed, Scopus, Web of Science, Google Scholar).
- Use of PRISMA guidelines and independent reviewers to minimize selection bias.
- Meta-analysis with random-effects model to account for heterogeneity.
Weaknesses
- Mixed study designs (RCTs, cohort, case-control, non-randomized) reduce the overall certainty of evidence.
- High heterogeneity (I² = 69.73%) for serum creatinine outcome indicates substantial variability across studies.
- Potential publication bias indicated by funnel plot asymmetry, though trim-and-fill did not change results.
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Creatine is a supplement people take to build muscle. Some worry it might damage kidneys because it raises a blood marker called creatinine. But creatinine is a waste product from muscles, and if you take creatine, you make more of it. This study looks at many past studies and finds that while creatinine levels go up a little, a better test of kidney health (called GFR) doesn't change. That means creatine probably doesn't harm kidneys.
Research results
People taking creatine had a tiny increase in creatinine (0.07 units) compared to those not taking it. But their kidney filtration rate (GFR) was the same. The increase in creatinine was only noticeable in the first week and after 3 months, not in between.
What this means - more context
The rise in creatinine is very small and unlikely to matter for healthy people. Doctors usually look at GFR, which didn't change, so creatine seems safe.
To systematically review and meta-analyze the effects of creatine supplementation on kidney function, specifically serum creatinine and glomerular filtration rate (GFR).
Creatine supplementation is associated with a small but statistically significant increase in serum creatinine (MD 0.07 µmol/L, 95% CI 0.01–0.12), but no significant change in GFR. The creatinine increase is transient and duration-dependent, with significant effects at <1 week and >12 weeks, but not between 1–12 weeks. The authors conclude that the rise in creatinine reflects increased creatine metabolism rather than renal impairment, and that creatine is safe for kidney function in healthy and clinical populations at standard doses.
Methods Used
Systematic review and meta-analysis following PRISMA guidelines. Searched PubMed, Scopus, Web of Science, and Google Scholar for studies from January 2000 to March 2025. Included human studies of any design that assessed serum creatinine or GFR after oral creatine supplementation. Random-effects model used for meta-analysis, with subgroup analysis by supplementation duration.
Main Finding
Meta-analysis of 12 studies (177 creatine users, 263 controls) found a statistically significant increase in serum creatinine (MD = 0.07 µmol/L; 95% CI: 0.01–0.12; p=0.03). Subgroup analysis showed significant effects in studies ≤1 week (MD=0.12; 95% CI:0.03–0.21) and >12 weeks, but not 1–12 weeks. Meta-analysis of 5 studies (69 creatine, 74 controls) found no significant change in GFR.
Confidence Level
Moderate. Heterogeneity for creatinine was substantial (I²=69.73%), and risk of bias was rated 'some concern' in most studies. Publication bias was suggested by funnel plots but trim-and-fill analysis did not change results.
Study Flags
Red Flags
- •Substantial heterogeneity for creatinine outcomes
- •Risk of bias rated as 'some concern' in included studies
- •Potential publication bias suggested by funnel plots
Surprising Findings
Despite a statistically significant increase in serum creatinine, GFR—the most accurate measure of kidney function—remains completely unchanged.
Commonly, elevated creatinine alarms doctors, but here it's a false alarm because the increase is due to increased creatine breakdown, not reduced kidney function.
Practical Takeaways
If you're taking creatine and get a blood test showing elevated creatinine, don't panic—ask your doctor to check GFR as well.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 547 / 100
Probability of being correct
Systematic reviews and meta-analyses of cohort studies. They sit above a single cohort study but below a single randomized trial, because the underlying evidence is still observational.
Human Meta-Analysis
Subject
Moderate probability
on the GRADE evidence scale
Think of this as a big report that combines many smaller studies about creatine and kidney health. It found that taking creatine slightly raises a substance in your blood called creatinine, but it didn't see any harm to how well your kidneys filter blood. But because the studies were different types and some were not very strong, we can't say for sure that creatine causes those changes—just that they happen together.
Strengths
- Comprehensive literature search across multiple databases (PubMed, Scopus, Web of Science, Google Scholar).
- Use of PRISMA guidelines and independent reviewers to minimize selection bias.
- Meta-analysis with random-effects model to account for heterogeneity.
Weaknesses
- Mixed study designs (RCTs, cohort, case-control, non-randomized) reduce the overall certainty of evidence.
- High heterogeneity (I² = 69.73%) for serum creatinine outcome indicates substantial variability across studies.
- Potential publication bias indicated by funnel plot asymmetry, though trim-and-fill did not change results.
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
This report is like a mix of many studies, some better than others. It looked at 21 studies and combined their results, which is nice. But many of these studies were small, short, and not all were randomized. That means the results might be a bit shaky, so we should be careful before saying creatine is completely safe for everyone.
40 / 100
- COI disclosure+40/40
- Data availabilitydata not shared
- Code availabilitycode not shared
0 / 100
- Randomizationnot randomized
- Blindingblinding unclear
- Control groupno control group
- Sample sizeno sample size reported
- Follow-upno follow-up reported
100 / 100
77 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervals+15/15
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 547 / 100
Probability of being correct
Systematic reviews and meta-analyses of cohort studies. They sit above a single cohort study but below a single randomized trial, because the underlying evidence is still observational.
This design cannot establish causation — the findings describe an association, not a cause. This systematic review and meta-analysis includes a mix of study designs (RCTs, cohort, case-control, and non-randomized trials). While RCTs could potentially establish causation, the pooling of both randomized and observational studies makes it impossible to attribute causality with confidence. The observed associations may be influenced by confounding and bias inherent in observational designs.
COI Unknown
Could not determine conflict of interest status
No conflict of interest statement is provided in the text. The presence of conflicts or funding cannot be determined from the available information.
The study text does not disclose author affiliations, funding sources, or any potential conflicts of interest. Without this information, it is impossible to assess the severity of any bias. The methods describe a standard systematic review process with independent reviewers, but no explicit safeguards against funder influence are mentioned.