Creatine: The Complete Evidence-Based Guide

If you only ever take one supplement, the evidence says it should be this one. Creatine monohydrate has been studied in hundreds of randomised trials over three decades. It is cheap, it is safe, and it works for almost everyone who trains. It is also surrounded by more myths per gram than any other product in the supplement aisle. This guide covers what creatine does, how to use it, and which of the fears about it survive contact with the data.

What creatine is and where it comes from

Creatine is a compound your body makes from three amino acids (arginine, glycine and methionine) in the liver and kidneys, and that you also eat in meat and fish. About 95 percent of it is stored in skeletal muscle, mostly as phosphocreatine.

Phosphocreatine has one job: it donates a phosphate group to regenerate ATP, the molecule that actually powers a muscle contraction, during the first several seconds of a hard effort. A heavy set of five, a sprint, a jump. When phosphocreatine runs low, power output drops and you have to slow down or stop.

Your muscles are normally about 60 to 80 percent saturated with creatine. Supplementation pushes that toward 100 percent. That extra 20 to 40 percent of stored energy is the whole mechanism. Everything else, the extra reps, the extra kilos, the extra muscle, follows from it (Kreider et al. 2017).

What the evidence says it does

Strength and power. Across dozens of trials, creatine combined with resistance training produces roughly 5 to 15 percent greater gains in strength and power than training alone (Branch 2003; Kreider et al. 2017). The effect is most visible in short, maximal efforts: the fifth rep of a heavy set, repeated sprints, a max jump.

Muscle mass. Because creatine lets you do slightly more work in every session, it increases lean mass over time. Meta-analyses in both young and older adults show consistent additional gains of around 1 to 2 kg of lean mass over a training block compared with placebo (Chilibeck et al. 2017). Some of that early gain is water, which we come back to, but the long-term difference is real tissue.

Recovery and training tolerance. Creatine reduces markers of muscle damage after hard sessions and supports glycogen resynthesis when taken with carbohydrate, which helps you absorb higher training volumes (Kreider et al. 2017).

The brain. This is the newer frontier. The brain uses creatine too, and supplementation modestly improves short-term memory and reasoning, with the clearest effects in people whose baseline stores are low: vegetarians, older adults, and the sleep-deprived (Avgerinos et al. 2018; Forbes et al. 2022). The effect sizes are small, but the safety profile makes it an easy bet.

Older adults. Creatine with resistance training improves strength and lean mass in people over 50 more than training alone, which matters for the falls-and-frailty side of ageing (Chilibeck et al. 2017). See Strength Training for Longevity.

Who responds and who does not

Roughly 20 to 30 percent of people are "non-responders" in the narrow sense that their muscle creatine is already high, usually because they eat a lot of meat and have a naturally high baseline. They gain less from supplementation because there is less room to fill. Vegetarians and vegans, who eat almost no dietary creatine, sit at the other end and tend to see the largest effects (Kreider et al. 2017).

You cannot know your baseline without a muscle biopsy, so the practical approach is to take it for 8 weeks alongside a consistent program and judge the trend in your training log, not the scale.

How to take it

Form. Creatine monohydrate. Every claim about "buffered", "HCl", "ethyl ester" or "nitrate" versions being better absorbed or gentler has failed in head-to-head trials, and several are less stable or less effective (Kreider et al. 2017). Monohydrate is also the cheapest. Buy it micronised if you want it to dissolve better.

Dose. 3 to 5 grams per day, every day, including rest days. Heavier people and people with a lot of muscle sit at the top of that range. Some recent work suggests 5 to 10 g/day may be needed to affect brain creatine, since the brain takes it up more slowly, but the evidence there is still early.

To load or not to load. Loading means taking about 20 g per day (0.3 g/kg), split into four doses, for 5 to 7 days, then dropping to a maintenance dose. It saturates muscle in about a week. Skipping the load and taking 3 to 5 g/day reaches the same saturation in roughly 3 to 4 weeks (Hultman et al. 1996). The destination is identical. Load if you want the benefit sooner and do not mind a slightly higher chance of stomach upset; skip it if you would rather ease in.

Timing. The research on pre- versus post-workout timing shows differences that are small and inconsistent. What matters is that the muscle is saturated, and that is a function of daily consistency, not clock time. Taking it with a meal, especially one containing carbohydrate and protein, may improve uptake a little via insulin. The best time is whichever time you will actually remember.

Cycling. There is no need to cycle off. Long-term studies up to five years show no down-regulation of your own creatine production that persists after stopping, and stopping simply returns stores to baseline over about four weeks (Kreider et al. 2017).

Hydration. Drink normally. The advice to drink extra water on creatine is folk wisdom, not a requirement, though hydration always matters for training.

The water weight question

Expect to gain 1 to 2 kg in the first two to four weeks. This is water, and it is important to understand where that water goes.

Creatine is osmotically active, so as the muscle cell takes up creatine it draws water in with it. That is intracellular water: inside the muscle fibre. It makes muscles look fuller and slightly larger, and there is some evidence that cell swelling itself is a mild anabolic signal. It is not subcutaneous water under the skin, and controlled studies do not show creatine consistently increasing extracellular water or making people look soft (Antonio et al. 2021).

If you track weight in an app, expect a step change and then a plateau at the new level. See Signal vs Noise: Real Strength Progress for why a single week of scale data is nearly meaningless anyway.

Side effects: what the trials actually show

Kidney function. Creatine raises serum creatinine, the by-product doctors use as a rough marker of kidney filtration. That can make a routine blood test look worse than it is. Studies that measure actual kidney function directly, including in people taking creatine for years, show no harm in healthy adults (Kreider et al. 2017; Antonio et al. 2021). If you have pre-existing kidney disease, or take medication that affects the kidneys, speak to your doctor before starting. If you get blood work, tell the person interpreting it that you take creatine.

Hair loss. One 2009 study in rugby players found that a creatine loading phase raised DHT, a hormone associated with male-pattern hair loss. It did not measure hair, had 20 participants, and has never been replicated. Twelve subsequent studies measuring testosterone and related hormones found no consistent effect (Antonio et al. 2021). The evidence for creatine causing baldness is, at present, nothing.

Cramping and dehydration. Repeatedly studied in athletes training in heat, and repeatedly not found. If anything, creatine-supplemented athletes report fewer cramps, probably because the extra intracellular water helps (Kreider et al. 2017).

Stomach upset. Real, mostly during loading, and mostly dose-dependent. Splitting doses, taking it with food, and using a properly dissolved micronised powder fix it for nearly everyone.

Weight gain. Real, and covered above. If you compete in a weight-class sport, plan for it.

Adolescents. The position of the International Society of Sports Nutrition is that creatine is acceptable for younger athletes who are past puberty, training seriously, eating well and supervised. It is not a shortcut for kids who have not learned to train.

Creatine for specific groups

• Women. The dosing is the same and the response is at least as good. There are additional reasons to be interested during pregnancy, perimenopause and menopause. We cover the evidence in Creatine for Women.
• Vegetarians and vegans. The strongest responders, for both muscle and cognition, because dietary intake is near zero.
• Endurance athletes. Less direct benefit, since the phosphocreatine system matters little at steady pace, but useful for surges, sprint finishes and for the strength work that supports endurance.
• Older adults. Strong evidence for strength, function and possibly cognition when combined with training.

Where creatine fits in your stack

Creatine is one of the very few supplements that earns a place on the evidence alone. It belongs alongside adequate protein and caffeine in the tier of things that actually work. Everything else is a distant second, and most of it does nothing. See Supplements That Actually Work for the full ranking.

Pair it with a plan that lets you use the extra capacity: progressive overload in a sensible split, tracked so you can see whether the extra rep actually showed up. If you are not applying progressive overload, creatine has nothing to amplify.

The bottom line

Take 3 to 5 g of creatine monohydrate every day. Load for a week if you want, or do not. Expect a kilo or two of water inside your muscles, more reps at the end of hard sets, and slightly more muscle after a few months of good training. Ignore the exotic forms, the timing debates, and the kidney and hair-loss folklore. Then get back to the training, because that is the part that actually builds the muscle.

Sources

• Kreider RB, Kalman DS, Antonio J, et al. "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, 2017.
• Antonio J, Candow DG, Forbes SC, et al. "Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show?" Journal of the International Society of Sports Nutrition, 2021.
• Branch JD. "Effect of creatine supplementation on body composition and performance: a meta-analysis." International Journal of Sport Nutrition and Exercise Metabolism, 2003.
• Chilibeck PD, Kaviani M, Candow DG, Zello GA. "Effect of creatine supplementation during resistance training on lean tissue mass and muscular strength in older adults: a meta-analysis." Open Access Journal of Sports Medicine, 2017.
• Hultman E, Söderlund K, Timmons JA, Cederblad G, Greenhaff PL. "Muscle creatine loading in men." Journal of Applied Physiology, 1996.
• Avgerinos KI, Spyrou N, Bougioukas KI, Kapogiannis D. "Effects of creatine supplementation on cognitive function of healthy individuals: a systematic review of randomized controlled trials." Experimental Gerontology, 2018.
• Forbes SC, Cordingley DM, Cornish SM, et al. "Effects of creatine supplementation on brain function and health." Nutrients, 2022.