Creatine side effects are, for healthy adults, almost entirely myth. Across more than 500 studies spanning three decades, the only consistently observed effect of creatine monohydrate at 3 to 5 grams a day is a small increase in water held inside muscle cells. No kidney damage. No liver damage. And, as of 2025, no hair loss.

That last one is new, and it is the reason this article exists. For sixteen years the hair loss warning rested on a single study that never measured anyone’s hair. In 2025, researchers finally ran the trial that did.

The short version

• Creatine monohydrate is the most studied supplement in sports nutrition, with over 500 published studies across more than 30 years.
• The kidney damage myth comes from misreading a blood test. Creatine raises creatinine, which is a marker of kidney function, without harming the kidney.
• The hair loss myth comes from one 2009 study of 20 rugby players that measured DHT and never measured hair.
• A 2025 randomised controlled trial was the first to assess hair follicle health directly. It found no difference between creatine and placebo.
• Weight gain is intracellular water, not bloating or fat.
• Loading phases are optional. They speed up saturation, not the end result.
• The one real caveat: if you have existing kidney disease, speak to a doctor first.

What is creatine? Creatine is a compound your body makes from amino acids and stores mostly in skeletal muscle, where it helps regenerate ATP, the molecule that powers short bursts of intense effort. You also get it from food, primarily red meat and fish. Creatine monohydrate is the supplemental form with the overwhelming majority of the research behind it. It is not a hormone and not a steroid.

Does creatine damage your kidneys?

No, not in people with healthy kidneys. This is the most persistent of all creatine side effects and it comes from a misunderstanding of a blood test.

Doctors assess kidney function partly by measuring creatinine, a waste product filtered out by the kidneys. High creatinine can indicate the kidneys are struggling. Creatine supplementation raises blood creatinine directly, because creatinine is what creatine breaks down into. The number goes up. The kidney is fine.

The International Society of Sports Nutrition position stand, which reviewed the full evidence base, states that creatine does not cause renal dysfunction in healthy populations. Studies running up to five years in healthy athletes have found no adverse effects on kidney function markers.

The concerns about renal toxicity in the literature trace to two published case reports, and in one of those the patient had a documented pre-existing kidney condition.

Who should actually be cautious?

Anyone with existing kidney disease or impaired renal function. The safety data applies to healthy kidneys, and extrapolating it further is not supported. If that describes you, this is a conversation for your doctor rather than an article.

Worth mentioning to your doctor before any blood test too, since an elevated creatinine reading in a creatine user can prompt unnecessary investigation.

Does creatine cause hair loss?

The evidence says no, and in 2025 that answer became considerably firmer.

Where the claim came from

One study. In 2009, van der Merwe and colleagues gave 20 college-aged rugby players a loading protocol of 25 grams a day followed by 5 grams a day, and measured their hormones after three weeks. Dihydrotestosterone, or DHT, rose 56% during loading and settled around 40% above baseline.

DHT is the androgen associated with male pattern baldness in genetically predisposed men. The reasoning went: creatine raises DHT, DHT causes hair loss, therefore creatine causes hair loss.

Three problems with that chain. DHT values stayed within normal clinical ranges throughout. The creatine group started with lower baseline DHT than the control group, which made the percentage increase look larger than it was. And the study never measured hair at all. No participant reported hair loss because nobody was asked.

No subsequent study replicated the DHT finding at maintenance doses of 3 to 5 grams a day.

What the 2025 trial found

Researchers recruited 45 resistance-trained men aged 18 to 40 and randomly assigned them to 5 grams of creatine monohydrate daily or 5 grams of maltodextrin placebo for 12 weeks, measuring total testosterone, free testosterone, DHT and hair follicle health.

There were no significant differences in DHT levels, the DHT-to-testosterone ratio, or hair growth parameters between the creatine and placebo groups (randomised controlled trial, PMID 40265319, 2025).

The authors describe it as the first study to directly assess hair follicle health following creatine supplementation, and as strong evidence against the claim.

One thing worth disclosing, because almost no coverage does: an author of that trial is a scientific advisor to a creatine brand and received creatine donations from a manufacturer for research purposes. That does not invalidate the findings, which used a placebo control and are consistent with the wider literature. It is the kind of thing you should know.

For sixteen years the hair loss warning rested on a single study that never once looked at anyone’s hair.

Is creatine a steroid?

No. Creatine is not a hormone, not an anabolic steroid, and not structurally related to either.

It is a compound built from amino acids, produced naturally by your liver, kidneys and pancreas, and present in ordinary food. A serving of red meat or fish contains roughly one to two grams. Your body makes about a gram a day on its own.

Anabolic steroids are synthetic derivatives of testosterone that act on hormone receptors to change gene expression. Creatine works by increasing the phosphocreatine stored in muscle, which lets you regenerate ATP faster during short bursts of intense effort. Different mechanism, different category, different regulatory status.

Creatine is classified as a dietary supplement, is not on any prohibited substance list, and is legal in every sport including the Olympics.

The confusion is understandable given that both are taken by people who lift, both come from tubs, and both produce visible results. The similarity ends there.

Does creatine make you bloated?

It increases the water held inside your muscle cells, which is not the same thing as bloating and does not look like it.

Creatine is osmotically active, meaning it draws water with it into the muscle. Typical scale weight increase is around 0.5 to 2 kilograms over the first one to two weeks as muscle saturates. That water sits inside the muscle cells, not under the skin, so the visual effect is fuller muscles rather than a softer midsection.

Subcutaneous water retention, the kind that actually reads as puffiness, is not what creatine produces.

What about stomach discomfort?

This is real and it is dose-dependent. Large single doses of 10 grams or more cause bloating and diarrhoea in some people, usually because undissolved creatine draws water into the gut.

Splitting the dose into 3 to 5 gram servings, dissolving it properly in enough liquid, and taking it with food resolves it for most people. If it does not, that is a reason to lower the dose rather than to stop.

Do you need a loading phase?

No. Loading changes how fast you saturate, not where you end up.

The standard loading protocol is around 20 grams a day split into four doses for five to seven days, then 3 to 5 grams daily. It saturates muscle creatine stores in about a week.

Taking 3 to 5 grams a day from the start reaches the same saturation point in roughly three to four weeks. Same destination, slower arrival, and with markedly less risk of the stomach discomfort that high single doses cause.

Unless you have a specific reason to want full saturation within days, skipping the loading phase is the simpler choice. It is also worth noting that the 2009 study behind the hair loss claim used a loading protocol, while the 2025 trial that found nothing used 5 grams a day.

Do you need to cycle off?

No evidence supports cycling. Your body does not stop producing creatine, receptors do not downregulate in any meaningful way, and long-term continuous use up to five years shows no adverse effects in healthy people.

Does creatine cause cramping or dehydration?

The research points the opposite way. Studies show creatine does not increase the risk of dehydration, cramping or heat illness, and may actually reduce these risks during exercise in heat.

The theory behind the myth was that creatine pulls water into muscle and therefore away from elsewhere, leaving you short. It sounds plausible and has not held up. Reports in popular media linking creatine to muscle strains, cramps and heat intolerance are not supported by the medical literature.

Studies in athletes and military personnel, which is where heat stress and hydration get studied seriously, indicate a substantial safety margin for both short and long-term supplementation in healthy adults.

Normal sensible hydration applies, as it would with any training. Nothing additional is required because of creatine.

Why does creatine do nothing for some people?

Because they were already saturated. Response depends on how much creatine your muscles held before you started, and that depends largely on diet.

People who eat a lot of red meat and fish carry higher baseline muscle creatine, so supplementing adds less. Vegetarians and vegans are the strongest responders, because dietary creatine comes almost exclusively from animal foods and their baseline stores are lowest.

Estimates put non-responders at somewhere between 20 and 30 percent of users, though the term is slightly misleading. It usually means a smaller effect rather than no effect.

If you have taken creatine for eight weeks with no change in bodyweight and no change in performance on short, heavy sets, you are probably in that group. That is a reason to stop spending money on it, not a sign anything went wrong.

What changed in 2026

Two things worth knowing if you last read about creatine a few years ago.

The hair loss question moved from open to closed. Until 2025, every honest article had to say the evidence was thin in both directions, because nobody had measured hair. The randomised trial described above changed that. The claim now sits alongside kidney damage as a myth with a specific origin and a direct refutation.

The research has broadened beyond muscle. Work on creatine and cognitive function, particularly under sleep deprivation and in older adults, has expanded considerably. That evidence is genuinely promising and genuinely earlier-stage than the muscle research, and it deserves its own article rather than a confident paragraph here.

What the evidence cannot tell you

Three limits.

Most safety data comes from healthy adults. Study populations skew toward young, trained men. Evidence in people with existing kidney, liver or metabolic conditions is thinner, which is why the caveat above matters.

The 2025 hair trial is one study. It is well designed, placebo controlled and the first of its kind, which makes it the best evidence available. It is not the same as a body of replicated work, and a single study should never be treated as final, including when it says what we would like to hear.

Supplement quality varies. The research is on creatine monohydrate, usually pharmaceutical grade. It does not transfer automatically to proprietary blends, alternative forms, or products that have not been tested for purity. The alternative forms marketed as superior, including HCl, ethyl ester and buffered versions, do not have comparable evidence behind them.

Common questions

How much creatine should you take?

The dose used across the great majority of research is 3 to 5 grams of creatine monohydrate daily. Larger doses do not produce better results once muscle is saturated, and increase the likelihood of stomach discomfort.

When should you take it?

Timing appears to matter very little. Muscle saturation is what produces the effect, and saturation depends on daily intake over weeks rather than on the hour you take it. Take it whenever you will consistently remember.

Is creatine monohydrate better than other forms?

It is the best evidenced by a wide margin, and it is usually the cheapest. Alternative forms are marketed on absorption claims that are not supported by comparable research.

Does creatine affect testosterone?

The 2025 trial found that changes in total and free testosterone over 12 weeks were independent of supplementation, occurring in both the creatine and placebo groups. If you are interested in what does and does not move male hormone levels, we covered the wider picture in the testosterone decline story.

Do you need to take creatine forever?

No, but the effect depends on saturation, so stopping means muscle stores gradually return to baseline over several weeks and the benefit goes with them. It is a maintained state rather than a permanent change.

Is creatine worth it if you do not lift?

The strength and power benefits come from being able to do more work in training, so without training there is less for it to amplify. The emerging cognitive research may change this picture, but it is not settled enough to recommend on.

What to take from this

Creatine side effects are an unusually clear case of how health myths persist. Each one has a traceable origin, each origin is a misreading rather than a finding, and each has survived for years after the evidence went against it.

The kidney claim is a blood marker misunderstood as organ damage. The hair loss claim is one small study that never looked at hair, now directly contradicted. The steroid claim is a category error. The bloating claim confuses water inside muscle with water under skin.

What remains is a compound found in food, produced by your own body, studied more thoroughly than almost anything else in sports nutrition, and costing a few cents a day.

If you have kidney disease, ask your doctor. Otherwise the honest summary is that the case against creatine never really had one.

For the broader picture on movement and long-term health, see our piece on what the step-count research actually shows, or browse the full Health section.

References

1. Kreider, R. B., et al. (2017). International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. Journal of the International Society of Sports Nutrition, 14, 18. PMID: 28615996
2. Does creatine cause hair loss? A 12-week randomised controlled trial (2025). 45 resistance-trained males, creatine monohydrate 5 g/day vs placebo. PubMed · Full text
3. van der Merwe, J., Brooks, N. E., & Myburgh, K. H. (2009). Three weeks of creatine monohydrate supplementation affects dihydrotestosterone to testosterone ratio in college-aged rugby players. Clinical Journal of Sport Medicine. [NO LINK]
4. International Society of Sports Nutrition position stand (2021), on creatine and hair follicle health. [NO LINK]

This article summarises published research and is not medical advice. If you have kidney disease, liver disease, or any other existing condition, speak to a qualified doctor before taking any supplement.