Creatine is one of the most-researched supplements in the world, but concerns around its safety have persisted. Misconceptions surrounding its impact on kidney function primarily stemmed from a number of individual case reports in the 1990s and 2000s which linked creatine supplementation to potential kidney dysfunction or failure.
These reports identified a link in individuals with a history of kidney disease, rather than healthy individuals. In addition, leading creatine researchers have noted that these case reports use a marker of kidney function that is unreliable in the context of creatine supplementation.
But even today, there is widespread belief that creatine can cause kidney damage in both healthy and diseased populations. This is despite several studies concluding that creatine supplementation does not adversely affect kidney function in healthy individuals, and small, emerging studies suggesting that creatine may also be safe in those with pre-existing kidney issues.
Why has creatine developed a reputation as being harmful to the kidneys?
The first prominent medical case report suggesting a link between creatine and kidney disease was published in The Lancet in 1998. The authors reported that a young man with pre-existing kidney disease experienced a decline in kidney function following creatine supplementation. This was based on medical tests which showed a spike in his serum (blood) creatinine levels, despite him otherwise appearing healthy.
While serum creatinine is commonly used as a marker of kidney dysfunction, individuals supplementing with creatine may naturally exhibit elevated creatinine levels despite having normal kidney function, explained Dr. Darren Candow, a professor at the University of Regina.
“When creatine is metabolized in skeletal muscle it diffuses from skeletal muscle as creatinine (a metabolic by-product of creatine without water),” he said. “Serum levels of creatinine are used to estimate the calculation of eGFR. Thus, if someone is supplementing creatine, their serum creatinine levels can rise which decreases the estimation of their eGFR.
“This alarms their doctor to conclude that they are in renal distress when it is highly likely only the metabolism of skeletal muscle creatine causing the ‘false’ alarm.”
What is eGRF?
An eGFR (estimated glomerular filtration rate) is a blood test that measures how well your kidneys filter waste from your blood. The test checks the level of creatinine, a waste product from muscle breakdown which is also a byproduct of creatine degradation.
In a paper published in the Journal of the International Society of Sports Nutrition, Candow et al. argued that the authors of the 1998 case study were aware of this limitation but that the information was ignored.
In response, two separate teams of experts in creatine metabolism wrote letters to the editor of The Lancet highlighting this oversight. However, several similar isolated case reports followed. and the notion that creatine supplementation leads to kidney damage or dysfunction continued to gain traction.
Creatine and the kidneys: What does the science say?
Since the early 2000s, there have been several experimental and controlled research trials evaluating the effects of creatine supplementation on kidney function demonstrating its safety.
For example, a major systematic review and meta-analysis published in BMC Nephrology last year concluded that while creatine supplementation is associated with a modest, transient increase in serum creatinine levels, this is likely due to metabolic turnover rather than renal impairment.
“These results indicate that creatine is likely safe for kidney function in healthy individuals and various clinical populations when used within standard dosing protocols,” the researchers wrote. “However, researchers and clinicians should interpret elevated serum creatinine levels in the context of supplementation with caution and consider more specific renal function markers for accurate assessment.”
In recent years, researchers have also begun to explore whether creatine could have benefits in certain populations with pre-existing kidney issues.
For example, a 2026 randomized controlled trial published in PLOS One explored whether giving creatine to people with kidney failure undergoing hemodialysis could be beneficial. Sixteen patients received a fixed creatine dose or a placebo via dialysate, with the results suggesting creatine was safe, well-tolerated and effectively increased patients’ pre-dialysis creatine concentrations. This is particularly relevant because dialysis patients can have low creatine stores and lose creatine during treatment.
A study exploring the effect of short-term, high-dose creatine supplementation in a young man with a single kidney also found that creatine was safe. Medical tests showed that while the patient’s creatinine levels spiked, his kidney function was preserved.
More broadly, a population-based study recently examined dietary creatine intake and cystatin C—a marker of kidney dysfunction—in almost 5,000 individuals. Higher dietary creatine intake was not associated with elevated cystatin C, including in individuals with kidney dysfunction.
Instead, the researchers observed an inverse association, raising the interesting possibility that creatine could play a reno-protective role. However, this was an observational study, so a cause-and-effect relationship could not be established.
Dr. Sergej Ostojic, a professor at the Department of Nutritional Sciences at Texas Tech University who co-authored the paper, said these findings are reframing the discussion from whether creatine poses a risk to kidney health to whether adequate creatine availability could benefit certain populations.
“Historically, we have been very cautious about creatine supplementation in people with kidney disease, mainly because we simply did not have enough direct evidence in this population,” he said. “While clinical supervision is appropriate, emerging evidence suggests that creatine may not only be safer than previously assumed but could potentially have benefits in select patients.”
Research gaps persist
Despite these promising results, there is not enough evidence to conclude whether creatine may benefit individuals with kidney disease, and Dr. Scott Forbes, associate professor at Brandon University, warned that caution is needed.
“There is limited evidence exploring the impact of creatine with pre-existing kidney disease or impaired kidney function,” he said. “We do have a large amount of data in healthy participants across the lifespan (young and older adults) showing that creatine is safe. There is some evidence in patients with type 2 diabetes, and there is a case study in a participant with a single kidney that show that creatine is safe.”
Dr. Candow agreed, adding that anyone with kidney disease or another health condition should get medical clearance before supplementing with creatine.
High-quality, long-term randomized trials in people with chronic kidney disease and other forms of impaired renal function are therefore still required. Dr. Ostojic highlighted the importance of studies using kidney-specific outcomes that are less influenced by creatine metabolism, such as cystatin C and directly measured GFR, alongside albuminuria and other markers of kidney injury.
“Overall, the evidence strongly supports renal safety in healthy people, while the evidence in people with kidney disease is still preliminary but increasingly encouraging,” he said. “The old idea that creatine is inherently ‘bad for the kidneys’ is simply not supported by the available evidence.”
