Creatine supplementation does not produce a well-documented change in urine odor. Creatinine, the breakdown product your kidneys filter into urine after creatine is metabolized, is largely odorless at normal concentrations. But the story has wrinkles: dehydration, gut bacteria, supplement purity, and even your own nose can all play roles in whether you notice something different after you start taking creatine.
How Creatine Leaves Your Body
Once creatine enters your system, most of it is taken up by skeletal muscle, where it helps recycle energy during short bursts of effort. The portion your muscles don’t absorb gets cleared through two routes: your kidneys filter some of it out directly, and the rest breaks down into creatinine, a waste product that also exits through urine.1PubMed. Pharmacokinetics of the dietary supplement creatine Creatinine is one of the most abundant solutes in human urine, right alongside urea, ammonia, and various organic acids.2PLOS ONE. The Human Urine Metabolome
The key point is that creatinine itself has no meaningful smell. Your body produces creatinine constantly from the natural turnover of muscle creatine, even without supplements. Taking creatine does raise the amount of creatinine your kidneys excrete, but a study comparing creatine loading doses to low daily doses in college football players found no significant change in urinary creatinine concentration with either approach.3PubMed Central. The Effects of Low-Dose Creatine Supplementation Versus Creatine Loading in Collegiate Football Players So the extra creatinine from supplementation, at least at common doses, may not meaningfully alter urine composition in a way you’d notice by smell.
The Dehydration Factor
If your urine does smell stronger after starting creatine, the most likely explanation has nothing to do with creatine itself. It has to do with water. Creatine pulls water into muscle cells, which is why many people gain a couple of pounds of water weight early in supplementation. That shift can leave less water available for urine production if you aren’t drinking enough to compensate.
Concentrated urine smells stronger than dilute urine. The same waste products are present either way, but in a smaller volume of water their concentrations rise and they become more detectable to your nose. Urea, ammonia, and various organic acids all contribute to that familiar sharp smell when urine is dark yellow rather than pale.2PLOS ONE. The Human Urine Metabolome If you’ve started creatine and noticed your urine looks darker or smells more pungent, increasing your water intake is the simplest fix. Most people on creatine benefit from adding at least an extra glass or two of water daily.
Gut Bacteria and Amine Byproducts
A less obvious pathway involves your gut microbiome. Not all creatine you swallow gets absorbed in the small intestine. Some of it reaches the large intestine, where bacteria can break it down into other compounds. Research on Clostridium species found that 26 out of 60 tested species could degrade creatine, converting it into N-methylhydantoin, and in the case of one species, into sarcosine as well.4PubMed. Degradation of various amine compounds by mesophilic clostridia These bacterial metabolites enter the bloodstream and are eventually filtered by the kidneys.
Whether these specific compounds smell in urine at the concentrations produced by creatine supplementation is not well studied. But the broader principle is established: gut bacteria routinely generate volatile amine compounds from dietary precursors, and some of those amines do have distinctive odors. The same bacterial ecosystem that breaks down creatine also processes choline, betaine, and other amine-containing nutrients into compounds like trimethylamine, which has a notably fishy smell.5PubMed Central. Trimethylaminuria: causes and diagnosis of a socially distressing condition People vary widely in their gut microbial composition, which means two people taking the same creatine dose could produce very different sets of bacterial byproducts.
This doesn’t mean creatine is giving you trimethylamine-scented urine. Creatine is structurally distinct from the precursors of trimethylamine. But the gut’s capacity to transform nitrogen-containing supplements into unexpected volatile compounds is real, and it may explain why some individuals notice subtle odor changes that others never do.
Supplement Purity and Contaminants
Creatine monohydrate is synthesized industrially from sarcosine and cyanamide, and the manufacturing process generates variable amounts of contaminants including dicyandiamide, dihydrotriazines, and creatinine itself.6PubMed. Creatine as nutritional supplementation and medicinal product An analysis of commercial creatine supplements found that creatinine was the most common organic contaminant, appearing above 100 mg/kg in about 44% of products tested. Roughly 15% of samples also contained detectable levels of dihydrotriazine compounds.7Food Chemistry. Levels of creatine, organic contaminants and heavy metals in creatine dietary supplements
None of these specific contaminants are famous for producing urine odor at the trace levels found in supplements. But the broader takeaway is that what’s in your creatine jar is not always pure creatine monohydrate, and cheaper products tend to carry higher contaminant loads. If you’re experiencing unusual urine odor and suspect your creatine, switching to a higher-purity product (look for third-party testing certifications like Creapure or NSF) is a reasonable step before blaming the creatine molecule itself.
When Smelly Urine Is Worth Investigating
Urine odor changes are common and usually harmless. Asparagus, coffee, certain B vitamins, and dozens of other foods and supplements alter urine smell in ways that are well recognized and temporary. But persistent strong odors, particularly a fishy smell, can occasionally point to something that deserves attention.
Trimethylaminuria is a metabolic condition in which the liver enzyme responsible for converting trimethylamine (TMA) into odorless trimethylamine N-oxide doesn’t work efficiently. People with this condition accumulate TMA, which is then excreted in urine, sweat, and breath, producing a persistent fishy odor.5PubMed Central. Trimethylaminuria: causes and diagnosis of a socially distressing condition It can be inherited or can develop secondary to other conditions. People with kidney disease, for instance, may experience worsened odor because uremia impairs the liver’s ability to oxidize TMA properly.8PubMed Central. Trimethylaminuria (fish malodour syndrome) in chronic renal failure
Creatine supplementation does not cause trimethylaminuria. But if you already have a mild, undiagnosed version of the condition, adding any supplement that increases the gut bacteria’s workload on nitrogen-containing compounds could theoretically make TMA production slightly more noticeable. This is speculative, and the connection between creatine and TMA specifically has not been studied. Still, if you notice a fishy or ammonia-like smell that persists regardless of hydration and doesn’t resolve after stopping creatine, it’s worth mentioning to a doctor.
Other causes of strong urine odor that have nothing to do with creatine include urinary tract infections (which often produce a cloudy, foul-smelling urine), uncontrolled diabetes (which can cause a sweet or fruity odor from ketones), and high-protein diets (which increase urea and ammonia in urine). If you started creatine around the same time you overhauled your diet or training routine, the dietary change could be the actual culprit.
Why Some People Notice and Others Don’t
Individual variation in odor perception is genuinely dramatic. A study that sequenced the olfactory receptor genes in 332 people found that genetic differences in a single odor receptor frequently altered how intensely a person perceived a given odorant. In 8 out of 10 validated cases, reduced receptor function correlated with reduced intensity perception.9PNAS. Genetic variation across the human olfactory receptor repertoire alters odor perception In plain terms, two people can smell the same urine and have genuinely different experiences of how strong or unpleasant it is.
This matters for the “does creatine make your pee smell” question because the anecdotal reports are mixed. Some people are emphatic that their urine smells different on creatine. Others, including many taking the same brand at the same dose, notice nothing. The genetic variability in smell perception, combined with differences in hydration habits, gut bacteria, diet, and supplement quality, means there’s no single answer that covers everyone. A person with highly sensitive olfactory receptors for nitrogen-containing compounds, a gut microbiome that aggressively metabolizes creatine, and a tendency to underhydrate could plausibly experience a noticeable change in urine odor. Someone else taking the same product might never detect a thing.
Practical Steps If You’re Bothered
If your urine smells off after starting creatine, work through the most likely causes in order:
- Drink more water. This is the fix for the vast majority of cases. Creatine increases intracellular water retention, so your kidneys need more fluid to keep urine at a normal concentration. Aim for pale yellow urine as a visual guide.
- Check your supplement quality. Cheap creatine products carry higher levels of manufacturing byproducts. A product with third-party purity certification will contain fewer contaminants that could contribute to unexpected metabolic effects.
- Evaluate your whole diet. Did you also increase protein intake, start eating more eggs or fish, or add other supplements around the same time? High-protein diets increase ammonia and urea in urine, and foods rich in choline can boost TMA production in the gut.
- Give it time. During a loading phase, you’re flooding your system with more creatine than your muscles can absorb at once. The excess gets cleared through urine and gut metabolism. After switching to a maintenance dose, the amount of unabsorbed creatine drops and any odor effect may fade.
If the odor persists after you’ve addressed hydration and ruled out other dietary changes, stopping creatine for a week is a simple diagnostic test. If the smell goes away and returns when you restart, creatine is involved in some way, even if the mechanism is indirect. If the smell persists regardless of creatine use, something else is going on.
Color Changes and Other Urine Surprises
People searching about creatine and urine smell often have a secondary concern: color changes. Creatine itself doesn’t color urine, but many people start creatine alongside a pre-workout supplement or multivitamin containing B vitamins, particularly riboflavin (B2), which turns urine a vivid fluorescent yellow. That color shift is harmless and unrelated to creatine.
Foamy urine is another occasional report. Excess creatinine in urine can very slightly increase surface tension, but foamy urine is more commonly caused by fast urination, dehydration, or, in rare cases, proteinuria (protein leaking into urine from the kidneys). If you notice persistent foaming that wasn’t there before, it’s worth checking in with a doctor, though the overwhelming evidence suggests creatine at standard doses does not harm kidney function in healthy people.
One oddity worth mentioning: because creatine supplementation raises baseline creatinine levels in the blood, it can throw off a standard kidney function test called the eGFR, which uses creatinine as a proxy for how well your kidneys filter. If you have bloodwork done while on creatine, your results might falsely suggest reduced kidney function when your kidneys are actually fine. Mentioning your supplement use to whoever orders the test can prevent unnecessary alarm.
The Nose Has the Final Word
Human olfactory sensitivity varies by roughly a thousandfold across individuals for certain compounds. A change in urine chemistry that registers as powerfully unpleasant to one person could be completely invisible to another, and neither is wrong. The research on creatine metabolism, gut bacterial transformation, and urinary composition tells us that creatine supplementation does alter what ends up in your urine, but the alterations are subtle, mostly involve odorless creatinine, and depend heavily on dose, hydration, and individual biology. The people who genuinely smell something different aren’t imagining it. The explanation is just more personal than chemical.