Creatine monohydrate: dosing, timing and the evidence

Creatine has more published research behind it than any other sports supplement, and it costs roughly a few cents per serving. That combination makes it unusual: most things with this much evidence are expensive, and most things this cheap have no evidence at all.

It is also surrounded by more folklore than almost anything else in the supplement aisle — loading protocols, timing windows, cycling schedules, and a persistent kidney rumour that refuses to die. Most of that is unnecessary.

What creatine actually is

Creatine is a compound your body already makes from three amino acids, and which you also get from meat and fish. Roughly 95% of it is stored in skeletal muscle, most of it bound to a phosphate group as phosphocreatine. ¹

A typical omnivorous diet supplies one to two grams a day, and the body synthesises about the same again. That is enough for normal function, but it leaves muscle stores only partially filled — usually around 60 to 80% of capacity. Supplementation exists to close that gap. ²

How it works

Very short, very hard efforts run on ATP, and muscle holds only a few seconds’ worth. Phosphocreatine is the fastest way to regenerate it — donating a phosphate group to turn spent ADP back into usable ATP almost immediately.

More stored phosphocreatine means that regeneration continues slightly longer before you have to slow down. In practice this shows up as an extra repetition, a marginally faster final sprint, or better recovery between hard sets.

This is also why the benefit shrinks as efforts lengthen. The phosphocreatine system is largely irrelevant to an hour of running, and the effect is concentrated in efforts lasting a handful of seconds.

It is worth not overstating that, though. The meta-analysis grouped tasks by duration and found small but statistically significant effects in all three bands — including efforts longer than 150 seconds, where the effect size was much the same as for short maximal work. ³ So “creatine does nothing for endurance” is too strong. Any benefit there is likely indirect, coming from better-quality interval sessions rather than from the phosphocreatine system doing anything useful during a steady hour.

What the benefits actually are

Strength and power

This is the best-supported outcome. Meta-analysis of resistance-training studies shows consistently greater gains in strength and lean mass in supplemented groups compared with placebo, across a wide range of training programmes. ³

Worth being precise about the size, because “well supported” and “large” are different claims. The meta-analysis pooling 100 studies reported effect sizes of roughly 0.17 for body composition and 0.24 for short maximal efforts — statistically clear, and small by convention. ³ It is a modest amplifier on training you are already doing, not a substitute for the training.

Lean mass

Some of the early increase is water drawn into muscle cells, which is why the scale often moves within the first week or two. Over longer periods the additional lean tissue appears to be genuine, mediated mostly by the extra training volume creatine allows.

Everything else

Claims around cognition, ageing, and mood are being actively researched and some early results are interesting. They are not yet at the level of confidence that supports the performance claims, and should be treated as promising rather than established.

Dosing and timing

Three to five grams per day is the whole protocol. Take it daily, including rest days. Muscle saturation depends on consistent intake over weeks, not on any individual dose.

A loading phase — roughly 20 g per day split across four servings for five to seven days — fills stores in about a week rather than three to four. ² It is faster, not better. Both approaches reach the same saturation point, and loading is the main cause of the stomach discomfort people report.

On timing: the evidence for a meaningful pre- versus post-workout difference is weak. Take it whenever you will remember to take it every day, because adherence matters far more than the clock.

On cycling: there is no need. Stores simply decline over about a month if you stop.

On form: monohydrate remains the reference standard. A buffered version marketed as substantially more potent was tested head-to-head against monohydrate at both its recommended dose and a monohydrate-equivalent dose, and produced no greater change in muscle creatine content, body composition, strength or anaerobic capacity. ⁴ It costs considerably more.

In fairness, that study was funded by a creatine monohydrate manufacturer, so it had an interest in the answer it got. We flag the same thing about the safety review above, and the standard should not move depending on whether a conflict happens to point the way we already lean. What makes the conclusion credible is not the study alone but that the buffered form’s own marketing claims have never been supported by peer-reviewed work at all.

Safety and side effects

The kidney concern originated from a misreading of a marker rather than from observed harm. Creatine supplementation raises serum creatinine, which is also the marker used to estimate kidney function — so a routine blood panel can look alarming without anything being wrong.

Studies looking directly at renal function in healthy adults have not found damage at standard doses. A meta-analysis pooling this question found exactly the pattern you would expect from a marker artifact rather than an injury: creatinine and urea readings shifted upward, and the authors nonetheless concluded that supplementation does not induce renal damage at the amounts and durations studied. ⁵ The blood test moves; the kidney does not.

Two honest limits on that. Only six studies met the bar for pooled analysis, so it is a thin evidence base by meta-analytic standards. And it speaks to healthy adults at ordinary doses — not to people who already have reduced kidney function. The largest safety review concluded that supplementation up to 30 grams a day for as long as five years is well tolerated in healthy people, across populations from infants to the elderly. ¹

One thing worth knowing about that review. It is a position stand from the International Society of Sports Nutrition, prepared at the request of a supplement-industry trade body, and several of its authors declare funding or consulting relationships with companies that sell creatine. That does not make it wrong — its conclusions line up with independent work, including the renal-function research above ⁵ — but a safety claim resting on an industry-adjacent review deserves to be read knowing that, and we would rather tell you than have you find out.

That said, if you have existing kidney disease, are pregnant, or take medication affecting renal function, this is a conversation for your clinician rather than an internet article.

The genuinely common side effects are minor: some water retention early on, and gastrointestinal discomfort that is mostly associated with large single doses. Splitting the dose or dropping the loading phase usually resolves it.

One practical note: tell your doctor you take creatine before any blood work, so an elevated creatinine reading is interpreted correctly.

The bottom line

Creatine monohydrate is cheap, well-studied, and modestly effective for exactly what it claims — short, hard efforts. Take three to five grams daily, buy the plain monohydrate, skip the loading phase unless you are impatient, and ignore anything marketed as an upgrade.

It will not compensate for insufficient protein, an unstructured programme, or poor sleep. Get those right first — then creatine is a small, reliable addition on top.