Quick answer

Creatine is a compound your muscles store for short, hard efforts. Taken at 3 to 5 g a day alongside strength training, it is one of the most studied supplements, and its evidence for strength is graded strong. Weight often rises 1 to 2 kg at first, mostly water.^1,2

Key facts

The body makes about 1 g of creatine a day, and meat and fish add more.¹
Taking creatine daily raises muscle stores by roughly 20 to 40 percent.²
A loading week fills muscle in about 6 days; a steady 3 g a day took about 28 days in the classic study.³
Creatine monohydrate is the most studied form, and pricier forms have not done better.¹

What creatine is

Creatine is made in the body from three amino acids and stored mostly in muscle. There it is kept as phosphocreatine, a quick reserve that rebuilds ATP, the cell's energy currency, in the first seconds of an intense effort such as a heavy set or a sprint.^1,2

The liver and kidneys make about 1 g of creatine a day from three amino acids: glycine, arginine and methionine.¹

A person weighing 154 pounds has about 120 g of creatine and phosphocreatine in the body, almost all of it in muscle.¹

A normal diet leaves muscle stores well short of full. A supplement tops them up, so you can do a little more work in repeated hard efforts. More work over weeks of training is where the measured gains in strength and lean mass come from.²

Creatine does little for steady exercise lasting more than about two and a half minutes, which relies on a different energy system.¹

What the evidence shows

Each claim below carries a grade. The grade says how much human research there is and how well it agrees, not how large the effect is. Beside each one is the amount the studies used.

Supports muscle strength during resistance training*^1,2,4

Strong evidence

A 2025 meta-analysis of 69 randomized trials (1,937 people) found that creatine plus resistance training added about 1.4 kg to bench or chest press and 5.6 kg to squat strength over placebo. Strength gains were seen at maintenance doses of 8 g a day or less and were clearest in younger adults, men and people who already train.

Amount studied: 3 to 8 g a day, with or without a loading phase

Supports performance in repeated short bursts of high-intensity exercise, such as sets of lifts or sprints*^1,2

Strong evidence

The NIH Office of Dietary Supplements and the International Society of Sports Nutrition (ISSN) both conclude that creatine improves repeated short, intense efforts; the ISSN puts the typical improvement after a loading phase at 10 to 20 percent in such tests. Most of these studies used about 20 g a day for 5 to 7 days, which matches the label's loading phase. It is of little value for endurance events.

Amount studied: About 20 g a day for 5 to 7 days, then 3 to 5 g a day

Supports gains in lean body mass when combined with resistance training*^1,2,5

Moderate evidence

A meta-analysis of 35 randomized trials (1,192 people) found that creatine added about 1.1 kg of lean body mass when combined with resistance training, and nothing measurable without exercise. Men gained about 1.5 kg; the gain in women (about 0.3 kg) was not statistically significant, and part of the early gain is water held in muscle, so the grade is moderate.

Amount studied: 3 to 5 g a day with resistance training, often after a loading phase

May support working memory for a short time at loading doses (20 g a day); not shown at 5 g a day*⁶

Early evidence

The European Food Safety Authority reviewed 23 human studies in 2024 and concluded that a cause-and-effect link between creatine and cognitive function has not been established. The few positive findings came from small studies using 20 g a day for 5 to 7 days, one of them during sleep deprivation; doses of 2.2 to 14 g a day and the largest trial (123 adults, 5 g a day for 6 weeks) found no significant benefit.

Amount studied: 20 g a day for 5 to 7 days

How much people take

3 to 5 g a day keeps muscle stores full for most people after a loading phase. The ISSN notes that larger athletes may need 5 to 10 g.^1,2

A loading week is optional. It reaches full stores sooner, and a smaller daily amount gets to the same place in about a month. The dosage guide sets out the amounts by goal and by body weight.³

Muscle stores drift back to their starting level about 4 to 6 weeks after stopping.²

Forms and food

Creatine monohydrate is 88% creatine by weight and is the most widely used and studied form.¹

Other, usually more expensive forms such as creatine ethyl ester and buffered creatine have not been shown to raise muscle creatine better than monohydrate, or to be easier to digest, more stable or safer.¹

Animal foods contain creatine: beef has about 2 g per pound, pork about 2.3 g and salmon about 2 g.¹

People who eat little or no meat or fish start with lower stores, which is one reason the amount needed to fill them varies from person to person.²

What's in ours

What’s in ours

Creatine: Creatine Monohydrate, 5,000 mg per serving, from the label
Creatine + Electrolytes: Creatine Monohydrate, 5,000 mg per serving, from the label

Side effects, and who should ask first

Weight gain of about 1 to 2 kg in the first month, largely water held in muscle; it comes on faster with loading¹

Nausea, diarrhea or stomach upset have been reported by some users.¹

Muscle cramps and heat intolerance have been reported anecdotally; the ISSN review found that controlled studies do not support them^1,2

A small rise in blood creatinine on lab tests, without a change in estimated kidney filtration⁷

No tolerable upper intake level is set for creatine. NIH reports few safety concerns at 20 g a day for up to 7 days followed by 3 to 5 g a day, and says use for several years appears safe in healthy adults. The ISSN reports no harm in studies using up to 30 g a day for up to 5 years.^1,2

Ask your doctor first if you have kidney disease or reduced kidney function
Ask first if you are pregnant or nursing, or under 18
Ask first if you take medicines that affect the kidneys
Tell your doctor or the lab you take creatine before a kidney blood test, because it raises creatinine, the marker the test measures⁷

The official sources we use do not name a specific medicine that interacts with creatine. That is not the same as proof of safety: if you take a medicine that affects the kidneys, ask your doctor or pharmacist before starting.

Questions people ask

Does creatine cause hair loss?

The best direct test found no sign of it. In a 12-week randomized trial, resistance-trained men took 5 g a day or a placebo, and DHT, testosterone and measured hair growth did not differ.⁸

Is creatine hard on the kidneys?

In healthy adults, trials say no. A 2026 meta-analysis of 20 randomized trials found a small rise in blood creatinine, which is expected because creatine breaks down to creatinine, but no change in urea or estimated kidney filtration. Trials longer than a year are still few. If you have kidney disease, ask your doctor first.⁷

Does creatine work for women?

The research is thinner. In the 2025 pooled analysis, women taking creatine gained bench or chest press strength, while gains on other lifts and in lean mass were smaller than in men and not statistically significant. Most trials have been done in men.^4,5

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Sources

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.