Creatine Myths: Kidneys, Hair Loss and Water Weight

Creatine monohydrate is one of the most studied compounds in sports nutrition, with more than 500 peer reviewed papers behind it. It is also the one people are most nervous about, and that nervousness comes down to three fears: that it wrecks your kidneys, that it makes your hair fall out, and that it leaves you holding water you did not ask for.

Each fear has a real origin. But in every case the gap between what the research showed and what the internet turned it into is large. Here is what the studies measured, what they found, and where the evidence is thin.

Why the kidney myth exists at all

This is a measurement problem mistaken for a medical one. Creatine and phosphocreatine in muscle break down non enzymatically into creatinine, which enters the blood and is filtered out by the kidneys. Doctors therefore use blood creatinine as a proxy for filtration: high creatinine, the logic goes, means the filter is struggling.

But blood creatinine is not purely a filtration signal. It also tracks how much muscle you carry and how much creatine you eat, which is why men run higher than women and heavy meat eaters higher again. Take creatine and you add to the substrate pool that becomes creatinine, so the number drifts up with nothing happening to the filter. The 2021 International Society of Sports Nutrition review of creatine misconceptions puts it bluntly: increases in blood or urinary creatinine on creatine are unlikely to reflect any decrease in kidney function. It also summarises the earlier Persky and Rawson audit: 12 studies found no rise in serum creatinine, 8 found a rise that stayed inside the normal range, and only 2 found a reading above the normal limit, one of them no different to its control group.

The second origin is a single 1998 case report: a young man eight years into kidney disease and five years into an immunosuppressant started creatine, his creatinine rose, and it was written up. One person, already ill, on medication, with the known effect of dietary creatine on creatinine readings unaccounted for. That report is much of why your gym mate still warns you off.

What long term studies in healthy adults found

To know whether the filter is damaged you have to measure the filter, not the marker creatine inflates. Poortmans and Francaux compared people who had taken creatine for 10 months to 5 years against non users, measuring clearance of creatinine, urea and albumin rather than blood levels alone. Their 1999 paper found no differences in plasma contents, excretion rates or clearance, and concluded that filtration rate, tubular reabsorption and glomerular membrane permeability were normal in both groups.

In people who had used creatine for between 10 months and 5 years, clearance of creatinine, urea and albumin did not differ from non users, and glomerular filtration rate, tubular reabsorption and glomerular membrane permeability were normal in both groups.

— Long-term oral creatine supplementation does not impair renal function in healthy athletes, Medicine and Science in Sports and Exercise, 1999

Kreider and colleagues tracked 98 Division I college footballers across 21 months on a 69 item panel of blood and urine markers, renal markers included. Creatine users showed no significant differences across the panel.

The neatest design sidesteps the creatinine problem entirely. Gualano and colleagues ran a randomised, double blind, placebo controlled trial in healthy sedentary men taking roughly 10 grams a day for three months, measuring cystatin C, a filtration marker creatine does not distort. Cystatin C fell in both groups, pointing to filtration improving rather than declining, and no other renal parameter differed.

Pulling the field together, a 2019 systematic review and meta analysis in the Journal of Renal Nutrition screened 290 studies and concluded that creatine does not induce renal damage at the doses and durations studied.

The honest caveat: existing kidney disease

Everything above was measured in healthy adults. That is the population the evidence covers, and it is not the same claim as "creatine is fine for everyone".

If you already have reduced kidney function, the picture is thinner, and the controlled trials in clinical groups are small and short. One randomised, placebo controlled trial in 29 patients with peripheral arterial disease found no change in creatinine clearance after 8 weeks. But 29 people over 8 weeks is not a long term safety dataset, and peripheral arterial disease is not kidney disease.

There is a practical issue too. If you have kidney disease, your medical team is monitoring your creatinine closely, and creatine can move that number for reasons unrelated to your kidneys, muddying a test they rely on. Anyone with an existing kidney condition, or on medication affecting renal function, should talk to their doctor before starting.

Hair loss: what the 2009 rugby study reported

The entire creatine and hair loss conversation traces back to one small crossover study. Van der Merwe, Brooks and Myburgh gave 20 college aged rugby players in South Africa 25 grams a day of creatine with glucose for 7 days, then 5 grams a day for 14 days, against a glucose placebo, and measured resting androgens.

Testosterone did not change. Dihydrotestosterone, or DHT, rose 56 per cent after loading and was still 40 per cent above baseline after maintenance. The DHT to testosterone ratio rose 36 per cent, then settled 22 per cent above baseline. DHT is the androgen that binds receptors in genetically susceptible scalp follicles and drives male pattern hair loss, so the leap to "creatine makes you go bald" is easy to see.

Two things are worth knowing first. The finding has never been replicated in the sixteen years since. And the percentages are doing a lot of work: baseline DHT was 23 per cent lower in the creatine arm, 0.98 nanomoles per litre against 1.26 in placebo, so creatine climbed from a lower floor while placebo drifted down. Every value stayed inside the normal clinical range.

The study also measured hormones. It did not measure a single strand of hair.

What happened when someone finally measured hair

For roughly fifteen years the honest answer to "does creatine cause hair loss" was that nobody had looked. In 2025 somebody did. Lak and colleagues ran a 12 week randomised controlled trial in resistance trained men aged 18 to 40, assigned to 5 grams a day of creatine monohydrate or a maltodextrin placebo. Crucially they measured follicles, not just blood: alongside testosterone and DHT, they ran Trichogram testing and the FotoFinder system to capture hair density, follicular unit count and cumulative hair thickness.

Thirty eight of the 45 recruited men completed. There were no group by time interactions for any hormone or any hair outcome. Testosterone shifted in both arms, a time effect rather than a supplement effect, and there were no differences between creatine and placebo in DHT, in the DHT to testosterone ratio, or in any hair measure. The authors described it as the first study to directly assess hair follicle health on creatine.

That is a meaningful upgrade to the evidence, and not a closed case. Thirty eight men over twelve weeks cannot rule out a small effect over years, and androgenetic alopecia plays out across decades, not a season. "No evidence of harm" and "proven safe for hair" are different statements, and only the first is supported here. What can be said is that the one direct test found nothing, and the result the myth was built on did not reproduce.

Water weight: what actually moves in week one

This is not a myth so much as a misread. Something does happen to your body water, and the question is where it goes. Creatine is osmotically active and is pulled into muscle by a sodium dependent transporter, so water follows it into the cell to keep intracellular osmolality stable. That is a muscle cell mechanism, not a subcutaneous one. The soft layer people picture under the skin, blurring a jawline, is a different compartment entirely.

The measurement work backs this up. Powers and colleagues gave 16 men and 16 women 25 grams a day for 7 days then 5 grams for 21 days, took muscle biopsies, and measured total, extracellular and intracellular water by deuterium oxide and sodium bromide dilution. Muscle creatine, body mass and total body water all rose in the creatine group. Fluid distribution did not change.

So yes, the scale moves early, typically by 1 to 3 kilograms on a high dose loading protocol, and most of that is body water. It is not fat. The body composition data runs the other way: a 2024 meta analysis in the Journal of Strength and Conditioning Research pooled 12 studies in adults under 50 and found creatine alongside resistance training increased lean body mass by 1.14 kilograms and reduced fat mass by 0.73 kilograms compared with training alone.

If the scale bothers you, skip loading. Loading is what produces the fast jump. Starting at a standard daily serve reaches the same saturation over about three to four weeks, gradually enough that you never see it happen.

Cramping and dehydration: the evidence runs the other way

The theory was reasonable on paper. If creatine drags water into muscle cells, heavy sweating might leave you short in the extracellular compartment, meaning impaired thermoregulation and cramp. In the early 2000s that reasoning was solid enough that the American College of Sports Medicine advised against creatine for people training hard in the heat.

Then people measured it. Greenwood and colleagues tracked 72 Division I college footballers through a season in conditions up to 37 degrees Celsius and 91 per cent humidity, 38 of them taking creatine. Creatine users had significantly less cramping, less heat illness and dehydration, less muscle tightness, fewer strains and fewer total injuries. It was open label and players chose their own group, so not a randomised trial, but the direction is the opposite of the myth.

The 2021 International Society of Sports Nutrition review reaches the same conclusion and names the confusion: surveys where users self report cramping rarely control for other supplements or dose, and in one, 91 per cent of respondents were exceeding the recommended maintenance amount.

The bottom line

On kidneys, the evidence in healthy adults is strong. Creatine raises serum creatinine because creatinine is what creatine breaks down into, and studies measuring filtration directly, over durations up to five years, found normal kidney function. On hair, the myth rests on one unreplicated 2009 hormone study in 20 rugby players, and the one trial that measured follicles found no effect. On water, the scale does move early, that water goes into muscle cells rather than under your skin, and over months the data shows more lean mass and less fat. On cramping, the controlled data runs opposite to the fear.

The limits matter. Long term controlled data in people with existing kidney disease is limited, and creatine can distort a marker those people are monitored on. The hair evidence is one 12 week trial in 38 young men, not a multi year study in men already thinning. Absence of evidence of harm is not proof of safety.

Practically, the research consistently uses creatine monohydrate rather than newer, pricier forms, at modest daily doses taken consistently. A single ingredient product is the easiest thing to be sure about, which is how Ritua's Creatine Monohydrate for Men is made: 100 per cent pure micronised creatine monohydrate, a 3 gram serve, no fillers, flavours or sweeteners. And if you are managing a health condition or taking medication, talk to your doctor before adding it.

This article is general information, not medical advice, and is not a substitute for guidance from your doctor, particularly if you are managing an existing health condition or taking medication.

Frequently asked questions

My blood test came back with high creatinine. Should I stop taking creatine?

Take the question to your doctor, and tell them you supplement with creatine, because that context changes how the result should be read. Creatine raises serum creatinine directly, since creatinine is its breakdown product, so a higher reading on creatine does not by itself indicate anything about filtration. Where clinicians want a marker creatine does not distort, cystatin C is the usual alternative.

Is creatine safe if I have kidney disease?

The reassuring research on renal function was conducted in healthy adults, and long term controlled data in people with existing kidney disease is limited. That is a question for your treating doctor, who knows your kidney function and your medications, not one to settle from general research.

Does creatine actually raise DHT?

One 2009 crossover study in 20 rugby players reported DHT up 56 per cent after a week of loading and 40 per cent above baseline after maintenance, all within normal clinical limits. That result has not been replicated, and a 2025 randomised controlled trial found no difference in DHT or the DHT to testosterone ratio between creatine and placebo over 12 weeks.

Will creatine make my face look puffy?

The water creatine brings with it is drawn into muscle cells by a sodium dependent transporter, not into the subcutaneous layer under the skin, and dilution studies measuring total, extracellular and intracellular water found overall body water rose without fluid distribution changing. If you want to avoid a sudden shift altogether, skip loading and start at a standard daily serve.

How much weight will I gain in the first week?

A high dose loading protocol of roughly 20 grams a day typically adds about 1 to 3 kilograms of body mass, most of it body water. Starting at a standard daily serve instead reaches the same muscle saturation over about three to four weeks without the abrupt jump.

Does creatine cause cramping in hot weather?

The controlled data points the other way. A season long study of college footballers training in heat and humidity found creatine users had significantly less cramping, heat illness and dehydration than non users. Self reported cramping in surveys tends to come from people exceeding recommended doses and taking other supplements alongside.

Sources

• Long-term oral creatine supplementation does not impair renal function in healthy athletes. Medicine and Science in Sports and Exercise, 1999.
• Long-term creatine supplementation does not significantly affect clinical markers of health in athletes. Molecular and Cellular Biochemistry, 2003.
• Effects of creatine supplementation on renal function: a randomized, double-blind, placebo-controlled clinical trial. European Journal of Applied Physiology, 2008.
• Effects of creatine supplementation on renal function: a systematic review and meta-analysis. Journal of Renal Nutrition, 2019.
• Does creatine supplementation affect renal function in patients with peripheral artery disease? A randomized, double blind, placebo-controlled clinical trial. Annals of Vascular Surgery, 2020.
• Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show? Journal of the International Society of Sports Nutrition, 2021.
• Three weeks of creatine monohydrate supplementation affects dihydrotestosterone to testosterone ratio in college-aged rugby players. Clinical Journal of Sport Medicine, 2009.
• Does creatine cause hair loss? A 12-week randomized controlled trial. Journal of the International Society of Sports Nutrition, 2025.
• Creatine supplementation increases total body water without altering fluid distribution. Journal of Athletic Training, 2003.
• The effect of creatine supplementation on resistance training-based changes to body composition: a systematic review and meta-analysis. Journal of Strength and Conditioning Research, 2024.
• Cramping and injury incidence in collegiate football players are reduced by creatine supplementation. Journal of Athletic Training, 2003.