Researchers looked at 21 studies about creatine supplements—a popular product athletes use to build muscle—to see if they damage kidneys. They found that creatine does cause a small, temporary increase in a blood marker called creatinine, but this doesn’t mean your kidneys are actually being harmed. Another important kidney measurement called GFR stayed normal. The bottom line: creatine supplements appear safe for kidney function, though the small creatinine increase is real and temporary.

The Quick Take

  • What they studied: Whether taking creatine supplements—popular with athletes and gym-goers—actually damages kidney function or just makes certain blood tests look different.
  • Who participated: A total of 440 people across 12 studies: 177 people taking creatine supplements and 263 people not taking them. Most were healthy individuals, though some studies included people with medical conditions.
  • Key finding: Creatine supplements caused a tiny increase in serum creatinine (a blood marker) of 0.07 units, which was statistically significant but very small. However, GFR—the actual measure of how well kidneys filter blood—showed no harmful changes.
  • What it means for you: If you take creatine supplements, your doctor might see a slightly higher creatinine number on blood tests, but this doesn’t indicate kidney damage. It’s likely just your body processing the supplement normally. However, people with existing kidney problems should talk to their doctor before using creatine.

The Research Details

This was a meta-analysis, which means researchers searched for all published studies about creatine and kidney function from 2000 to 2025 and combined their results. They looked through four major scientific databases to find relevant studies. They then selected 21 high-quality studies to review in detail and used 12 of those studies with enough data to combine the numbers statistically.

The researchers used something called a random-effects model, which is a statistical method that accounts for differences between studies. They also looked at whether the length of time people took creatine mattered—comparing studies that lasted less than a week, 1-12 weeks, and more than 12 weeks.

They focused on two main kidney measurements: serum creatinine (a waste product in blood that kidneys filter out) and GFR (glomerular filtration rate, which measures how well kidneys actually work). These are the standard ways doctors check if kidneys are functioning properly.

This research approach is important because it combines results from many smaller studies to get a clearer picture than any single study could provide. Since concerns about creatine and kidney damage have been around for years, looking at all the evidence together helps separate real problems from false alarms. The subgroup analysis by time period is especially valuable because it shows whether any effects are temporary or long-lasting.

This study was published in BMC Nephrology, a respected medical journal focused on kidney health. The researchers were transparent about their methods and included 21 studies in their review. The fact that they found different results based on how long people took creatine suggests they looked carefully at the data. However, the studies they reviewed varied in quality and how they measured outcomes, which is normal for this type of research.

What the Results Show

When researchers combined all the data, creatine supplements caused a small but measurable increase in serum creatinine of 0.07 units (the range where they’re confident the true effect falls is 0.01 to 0.12). While this was statistically significant, meaning it’s unlikely to be due to chance, the actual increase is very small.

Interestingly, when they looked at how long people took creatine, the pattern changed. In studies lasting one week or less, the increase was larger (0.12 units). In studies lasting 1-12 weeks, there was barely any increase (0.04 units). In studies lasting more than 12 weeks, the increase became noticeable again.

The most important finding was about GFR—the actual measure of kidney function. There was no significant difference in GFR between people taking creatine and those not taking it. This suggests that even though the creatinine number goes up, the kidneys themselves are working normally.

The researchers noted that the temporary nature of the creatinine increase in the 1-12 week studies suggests the body may adapt to creatine over time. The return of higher creatinine in longer studies (over 12 weeks) might indicate a different pattern, though this needs more investigation. No studies reported serious kidney problems or kidney failure in people taking creatine supplements.

This research confirms what many smaller studies have suggested: creatine supplements don’t appear to damage healthy kidneys. The finding that creatinine goes up but GFR stays normal matches previous research showing that creatinine elevation alone doesn’t mean kidney damage. This meta-analysis provides stronger evidence than individual studies because it combines results from hundreds of people.

The studies reviewed had different designs and measured things slightly differently, which can affect results. Most studies involved healthy, young people, so we don’t know as much about older adults or people with existing health conditions. The number of studies looking at GFR was smaller than those looking at creatinine. Some studies were short-term, so we don’t know about very long-term effects. Finally, most participants were athletes or healthy volunteers, not people with kidney disease, so the findings may not apply to those groups.

The Bottom Line

For healthy people: Creatine supplements appear safe for kidney function based on current evidence (moderate confidence). If you take creatine, expect your creatinine blood test to be slightly higher, but this doesn’t indicate kidney damage. For people with kidney disease or kidney problems: Talk to your doctor before taking creatine, as this research doesn’t include enough people with kidney disease to be certain it’s safe for them. For everyone: Stay well-hydrated when taking creatine, as it draws water into muscles.

Athletes and gym-goers considering creatine supplements should know it appears safe. People getting routine blood work should understand that a higher creatinine number doesn’t automatically mean kidney problems. People with existing kidney disease, diabetes, or high blood pressure should consult their doctor first. Parents of young athletes should know the current evidence suggests safety, though long-term effects in teenagers need more study.

The creatinine increase happens quickly—within days to a week of starting creatine. If you stop taking it, creatinine levels return to normal within a few weeks. Any kidney damage, if it were to occur, would likely show up within the first few weeks, but this study found no evidence of actual kidney damage even with longer use.

Want to Apply This Research?

  • If taking creatine, track your daily water intake (aim for at least 8-10 glasses) and note any changes in urination patterns. Log your supplement use dates and amounts to correlate with any blood test results.
  • Set a reminder to drink water consistently throughout the day when taking creatine supplements. Use the app to log your creatine doses and create a note to discuss your supplement use with your doctor at your next appointment.
  • If you take creatine regularly, get baseline kidney function tests (creatinine and GFR) before starting, then recheck every 6-12 months. Use the app to track test dates and results, noting any changes over time. Monitor for any unusual symptoms like changes in urination, swelling, or fatigue.

This research summary is for educational purposes only and should not replace professional medical advice. While this meta-analysis suggests creatine supplements are safe for kidney function in healthy people, individual responses vary. If you have kidney disease, diabetes, high blood pressure, or are taking medications, consult your doctor before starting creatine supplements. Always stay well-hydrated when using creatine. This summary reflects current research but new evidence may emerge. Your healthcare provider can best assess whether creatine is appropriate for your individual health situation.