All compounds

Creatine

Also sold as creatine monohydrate, Creapure. Naturally occurring amino acid derivative; sold as a dietary supplement.

Well-characterised, low concern (1 of 5)

Creatine works, it is the most heavily studied supplement in sport, and after thirty years of people looking for the harm, nobody has found it.

What it is

Creatine is a compound your body already makes, mostly in the liver, and that you already eat if you eat meat or fish. It is stored in muscle, where it exists mostly as phosphocreatine.

The supplement version is creatine monohydrate: a white powder, chemically identical to what your body produces, sold legally as a dietary supplement in the United States, the United Kingdom, the European Union and most other places. It is not a drug, not a hormone, and not a stimulant. No pharmaceutical company abandoned it, because no pharmaceutical company ever needed to develop it — it has been sold cheaply and openly since the early 1990s.

We include creatine here for a specific reason. If everything on this site were rated dangerous, the ratings would carry no information. Creatine is the compound where the honest answer and the reassuring answer happen to be the same, and saying so is what makes the rest of the site worth reading.

What it actually does

Muscle contracting at maximum effort burns through its available energy in a few seconds. Phosphocreatine is the reserve that regenerates that energy fastest. Supplementing creatine raises the amount your muscle holds, which means the reserve lasts marginally longer and refills marginally faster.

In practice that produces a small, real improvement in repeated bursts of maximum effort — another repetition, a slightly faster second sprint — and, over weeks of training, a measurable increase in lean mass. Part of that increase is water drawn into muscle cells, and part is genuine tissue built because the training got slightly harder.

The effect is not dramatic. It is roughly what a well-conducted study of an effective supplement should look like: consistent, modest, and replicated many times. That is a much better description of creatine than either the marketing or the alarm around it.

There is also a real, less-established line of work on creatine and the brain, particularly under sleep deprivation and in vegetarians, whose baseline stores are lower. Treat that as promising rather than settled.

What the evidence actually shows

This is the part where creatine differs from everything else on this site: the evidence exists, in quantity, in humans.

There are hundreds of randomised controlled trials. There are meta-analyses pooling them, which continue to find a genuine strength benefit. There is a formal position stand from the International Society of Sports Nutrition reviewing both efficacy and safety, which is about as close to an institutional consensus as sports nutrition produces.

On the specific fear — kidneys — the evidence is unusually direct. Athletes taking creatine for extended periods have had renal function measured properly and it did not deteriorate. A 2023 review went back through the accumulated case reports that started the worry and concluded the association had not held up.

The honest limits: nearly all of this is in healthy adults, most of it in young men, and most trials run for weeks to months rather than decades. If you already have kidney disease, none of it was studied in you, and that is a real gap rather than a formality.

The risk profile

Well-characterised, low concern (1 of 5) — Studied properly, used widely, and the honest answer is that it is broadly fine.

What going wrong looks like from the inside

Creatine has no characteristic failure mode. There is no escalation pattern, no tolerance, no point at which stopping becomes difficult. On this site that is a genuinely unusual thing to be able to write, and we would rather write it plainly than manufacture a warning to seem balanced.

There is one thing that catches people out, and it is not a health problem — it is a laboratory problem. Creatine breaks down into creatinine, and serum creatinine is what most blood panels use to estimate kidney function. Taking creatine raises your serum creatinine without your kidneys doing anything wrong. If you have a routine blood test while supplementing, the result can look like early kidney impairment, and a doctor who does not know you take creatine may act on that.

The fix is trivial: tell whoever ordered the test that you take creatine. Say it before the blood draw if you can. This is worth knowing not because creatine is dangerous but because being investigated for kidney failure you do not have is an unpleasant few weeks.

The other honest note is water. Early on, some people gain weight quickly and feel puffy. That is fluid moving into muscle, it is not a warning sign, and it settles.

Interactions and combinations

Creatine has no meaningful interaction profile of the kind that matters elsewhere on this site. It is not a central nervous system depressant, it does not stack dangerously with alcohol or sedatives, and it does not potentiate anything.

The caffeine question comes up constantly. A small early study suggested caffeine might blunt creatine’s effect; it has not replicated convincingly. Treat it as unresolved and unimportant.

The one situation that deserves care is existing kidney disease, or drugs that are hard on the kidneys. Not because creatine has been shown to cause harm there, but because it has not been studied there and it will distort the blood test used to monitor you. That is a conversation to have with whoever manages the condition.

If you’re already using it

Then nothing here asks you to change anything, and there is no withdrawal to plan for. You can stop whenever you like; your muscle stores return to baseline over a few weeks and the water weight goes with them.

Two practical things. Tell any clinician who orders blood work that you take creatine. And buy plain creatine monohydrate rather than a proprietary blend — the monohydrate is the form nearly all of the research used, it is the cheapest form, and a blend mostly adds ingredients with a weaker evidence base at a higher price.

This page has not yet been reviewed by a clinician. It was written from the published literature and every claim is cited, but no named medical professional has checked it. We say so here rather than let a missing byline read as an implicit one.

Last reviewed 7 September 2026. Found something wrong? Corrections are published, not silently edited.