Creatine: does it work, and is it safe?

Walk into any gym changing room and someone will have an opinion on creatine. It builds muscle, it is a steroid, it wrecks your kidneys, it makes your hair fall out. Those claims cannot all be true. Creatine is one of the most researched supplements in sport, which means there is unusually good evidence to check them against. This guide explains what creatine does in the body, who is likely to notice a difference, how much people usually take and what the research says about the worries you hear most often. It is written for healthy adults who train; it is not advice for anyone with kidney disease or another medical condition.

What creatine actually does

Creatine is a natural compound found mainly in red meat and seafood, and your body also makes some in the liver and kidneys. According to the International Society of Sports Nutrition's position stand, about 95% of the body's creatine is stored in skeletal muscle, much of it as phosphocreatine. That store works like a quick-release battery. During short, intense efforts such as a heavy set or a sprint, it helps regenerate the energy muscles use, so you may manage an extra repetition or recover slightly faster between sets.

A normal diet supplies about 1–2 g of creatine a day, which leaves muscle stores roughly 60–80% full, the same position stand notes. Supplementing tops them up, typically raising muscle creatine by 20–40%. That is why creatine tends to help most with repeated short bursts rather than long, steady exercise. You will not feel it the way you feel caffeine, because it is not a stimulant. Any benefit builds slowly, through slightly better training sessions over several weeks.

Does it work?

For strength, the evidence is consistent. A meta-analysis of 53 trials in Sports Medicine found that creatine improved upper-body strength in exercises lasting under three minutes, such as the bench press, compared with a placebo, regardless of age, sex or training status. The improvement is modest rather than dramatic: think of a little more weight on a lift over a training block, not a transformed body. Most of the result still comes from training regularly, eating enough and sleeping well.

Creatine is less likely to help with long, steady efforts such as an easy run, because those rely more on other energy systems. It also does nothing on its own: the people in these trials were training. If you are not yet following a consistent plan, our beginner gym plan is a better first step than any supplement.

How much to take, and whether to load

The most studied form is creatine monohydrate, and two approaches reach the same place. A classic study in the Journal of Applied Physiology found that 20 g a day for six days raised muscle creatine by about 20%, and that 3 g a day reached a similar level more gradually, over 28 days. Loading simply gets there faster. The ISSN suggests 3–5 g a day once stores are full, and notes that larger athletes may need more.

Taking it consistently matters more than timing. Many people mix it into a drink with a meal; the ISSN notes that taking it with carbohydrate, or carbohydrate and protein, may help the body retain more. If you load, smaller servings through the day are easier on the stomach. Choose a product that lists creatine monohydrate as the ingredient, and remember that in the US the FDA does not approve supplements for safety and effectiveness before they are sold, so a third-party tested product is a sensible choice.

The worries, checked against the evidence

Does creatine cause water retention?

Some, early on. A 2021 review of common creatine questions by an international group of researchers notes that water retention is the most common side effect, mainly in the first several days, especially when loading. Creatine draws water into muscle cells along with it. Several training studies lasting five to ten weeks found no lasting increase in total body water. So an early jump on the scale is expected, and it is not fat.

Will it damage my kidneys?

Not at recommended doses in healthy people, as far as current research shows. A systematic review and meta-analysis in the Journal of Renal Nutrition concluded that creatine supplementation did not cause kidney damage in the amounts and durations studied. Part of the confusion comes from creatinine, a waste product of creatine that doctors use as a kidney marker; taking creatine can raise it without the kidneys being harmed. Tell your doctor you take it before a blood test. If you have kidney disease or reduced kidney function, do not start creatine without medical advice.

Does creatine cause hair loss?

There is no good evidence that it does. The idea traces back to a single study of 20 rugby players in which levels of the hormone DHT rose during three weeks of creatine. That study measured hormones, not hair. The 2021 review points out that the result has not been replicated and that DHT levels stayed within normal clinical limits. If you are worried about hair loss for other reasons, a GP or dermatologist can advise.

Women, older adults and other forms

Does creatine work for women?

Yes, although responses can differ. The 2021 review notes that women may start with higher muscle creatine levels, which could explain why some studies find smaller effects. It also describes a growing body of research in women after the menopause showing that creatine taken during a resistance training programme can improve muscle mass, upper- and lower-body strength, and everyday tasks such as standing up from a chair. As with men, the effect comes alongside training, not instead of it.

Is it useful for older adults?

It may be one of the more promising uses. Age-related loss of muscle, strength and function, called sarcopenia, raises the risk of falls and fractures. The same review describes growing evidence that creatine, particularly combined with exercise, brings muscle and performance benefits in older adults, and recommends pairing it with resistance training for the greatest effect. Larger and longer trials in frail older people are still needed, so anyone with health conditions should discuss it with their doctor first.

Are other forms better than monohydrate?

There is no good evidence that they are. The review found no peer-reviewed studies showing that creatine salts, creatine ethyl ester, buffered creatine, creatine nitrate or other marketed forms raise muscle creatine more than the same amount of monohydrate, and most showed less effect. Monohydrate is also the form used in nearly all the safety research. The powder keeps well when dry but breaks down in liquid over time, so mix it shortly before drinking; ready-made creatine drinks can contain only tiny amounts.

Who should be careful

Creatine is well studied in healthy adults; the ISSN reports that doses up to 30 g a day for five years were well tolerated in research. That does not make it right for everyone. Talk to a doctor first if you have kidney or liver disease or diabetes, or take medicines that affect the kidneys, and do not give it to children without medical advice. Competitive athletes should check their sport's rules on supplements and choose tested products. If you eat little or no meat or fish, your muscle creatine may start lower, because the main food sources are meat and seafood.

Creatine also does not replace food. Protein, enough overall energy and sleep do most of the work in building muscle. Our guides to protein per meal and what to eat around training cover the foundations that matter more than any tub.

A sensible way to start

If you train regularly and want to try it, choose plain creatine monohydrate, take 3–5 g a day with a meal, and keep your training and diet steady so you can tell whether it helps. Give it at least four weeks before judging. Expect a small rise on the scale at the start. Stop and seek advice if you feel unwell. And if you are not yet training consistently, start there: creatine can make good training a little more productive, but it cannot replace it.