Creatine: the complete guide

What is creatine, and how does it work?

Creatine is one of the most studied compounds in sports science, and one of the most misunderstood, weighed down by marketing for pricier forms and by safety myths that refuse to die.

It is a natural compound the body makes from three amino acids: arginine, glycine and methionine. The body needs to replace about 1 to 3 grams a day, and food supplies some of that if you eat meat and fish. About 95 percent of the body's creatine is stored in skeletal muscle, mostly as phosphocreatine [2].

During short, intense effort, muscles burn through ATP, the cell's immediate energy currency, in seconds. Phosphocreatine is the rapid backup: it hands a phosphate group back to spent ADP to rebuild ATP almost instantly [1][2]. Supplementing raises muscle creatine and phosphocreatine by about 20 to 40 percent, so more of this fast energy is on hand for the next hard reps or the next sprint [2].

On a normal diet, muscle creatine stores are only about 60 to 80 percent full, and supplements top them up. People who eat little or no meat or fish start with lower stores and may see larger gains in muscle creatine [2].

Which form of creatine should you choose?

Creatine monohydrate is the most researched form by a wide margin, it is inexpensive, and it is the benchmark every other form is measured against. The International Society of Sports Nutrition describes it as the most extensively studied and clinically effective form, and no other form has been shown to produce greater creatine retention [2].

A controlled trial comparing a buffered creatine with monohydrate found no advantage in muscle creatine content, body composition or training adaptations [3]. Creatine ethyl ester was promoted for better absorption, but in a seven-week trial alongside resistance training it raised blood creatinine more than monohydrate, raised blood creatine less, and gave no advantage in muscle creatine, strength or body composition [4].

Creatine is not stable in liquid: over time it turns into creatinine, faster at higher temperatures and in more acidic drinks, while monohydrate powder shows no signs of breakdown over years [5]. Mix the powder fresh.

The newer forms are not scams, but the extra cost buys solubility or convenience, not a documented edge in results. Every pricier form is measured against monohydrate, and none has convincingly beaten it.

What does creatine do for training?

Strength and power are the best-supported use. Alongside resistance training, creatine is associated with greater gains in maximal strength and high-intensity power than training alone. A 2003 review put the improvement in maximal power and strength from short-term use at about 5 to 15 percent [6], and the 2017 position stand reports gains of about 10 to 20 percent in high-intensity exercise performance; the figure depends on the measure and the people studied [2].

Part of the early gain on the scale is water inside muscle cells, but over weeks of training, creatine is associated with greater gains in lean mass. The likely reason is indirect: more fast energy lets you complete more quality reps and sets, and that extra training drives adaptation [2].

Recovery between hard sessions has been studied too, but those findings are more mixed than the strength data [2].

How much creatine should you take?

Dosing is simpler than the marketing makes it sound. The 2017 position stand describes two routes that work [2].

• Simple route: 3 to 5 g every day. Stores fill gradually over about three to four weeks, with no loading needed.
• Fast route: about 20 g a day, split into four 5 g doses, for 5 to 7 days, then 3 to 5 g a day. Loading speeds up the timeline; it does not raise the final level.
• With food: taking creatine with carbohydrate, or carbohydrate and protein, appears to increase how much muscle takes up.
• Consistency matters most. Daily intake keeps stores full. A dose at an imperfect time still counts; a skipped dose does not.

Is creatine safe?

Is it just water weight? Creatine does pull water into muscle cells, and the scale often moves a little in the first week. That water inside the cell is part of how creatine works, and over time the lean-mass gains in trained people reflect real tissue, not just fluid [2].

Does it harm the kidneys? In healthy people, reviews of short- and long-term use, including studies lasting years, have found no compelling evidence that creatine harms kidney function at recommended doses [2]. The confusion often comes from creatinine: creatine breaks down into creatinine, a blood marker used to estimate kidney function, so supplements can nudge that number up without any change in the kidneys [5]. Tell your doctor you take creatine before a blood test so the result is read correctly.

Does it cause hair loss? This worry traces almost entirely to one small 2009 study in college rugby players that reported a rise in DHT, a hormone linked to male-pattern hair loss, which stayed within normal clinical limits. That study measured a hormone, not hair, and it has not been replicated [5]. A 2025 randomized trial in resistance-trained men taking 5 g a day for 12 weeks found no difference from placebo in DHT or in hair density and thickness [7].

Creatine has one of the strongest safety records of any sports supplement. Still, anyone with reduced kidney function, anyone pregnant or breastfeeding, and anyone taking medicines that affect the kidneys should check with their doctor first. Occasional stomach upset is usually solved by splitting the dose and taking it with food.

Why does purity matter for creatine?

Because creatine is taken every day for long stretches, purity matters. Much of the research that established its safety and effectiveness used creatine monohydrate made in Germany [5]. A recognized third-party quality mark, such as NSF Certified for Sport or Informed Sport, is a reasonable way to confirm a product contains what the label states and little else.

For nearly everyone, plain creatine monohydrate at 3 to 5 g a day, taken consistently, is the sensible default.