Guide · Performance

Creatine: what science shows about strength, muscle, kidneys and hair

It is one of the most studied supplements in the world. The effect is real and moderate, and some fears were not confirmed in the studies.

In this article

1. What creatine is
2. Strength: what the meta-analyses show
3. Lean mass and muscle growth
4. Is creatine bad for the kidneys?
5. What about hair loss?
6. Beyond muscle: brain and ageing
7. How to track it
8. Frequently asked questions
9. Sources

What creatine is

Creatine is a substance the body makes from amino acids and also gets from food, mainly meat and fish. It is not a hormone or a drug: it is a compound that already circulates in your blood and is stored almost entirely in the muscles. There it is kept as phosphocreatine and helps regenerate energy quickly during short, intense efforts, such as a set of squats or a sprint.

The 2017 position stand of the International Society of Sports Nutrition sums up decades of studies: supplementation increases the creatine stored in muscle, which may explain the improvement in high-intensity exercise and greater training adaptations. This text describes what has been studied. It does not recommend use or an amount. That decision depends on your goal and your health, and should be made with a dietitian or doctor.

Strength: what the meta-analyses show

A 2017 meta-analysis in Sports Medicine pooled 53 placebo-controlled trials with more than 1,100 participants and assessed upper-body strength in exercises lasting up to three minutes. Creatine improved performance in the bench press and other chest and arm exercises, with a small to moderate effect.

One detail caught the authors' attention: the benefit appeared consistently, regardless of age, sex, activity level and how creatine was used in the studies. It is one of the reasons creatine is considered one of the few supplements with solid evidence for strength.

Lean mass and muscle growth

• 2024 meta-analysis, Journal of Strength and Conditioning Research: 12 trials in adults under 50. Added to strength training, creatine increased lean mass by 1.14 kg more than training alone and slightly reduced body fat.
• 2022 meta-analysis, Nutrition, with Brazilian researchers: 35 trials. The lean mass gain appeared when creatine was combined with strength training; without exercise there was no significant effect. Men responded more than women in these studies.
• 2023 meta-analysis, Nutrients: 10 trials with direct muscle measurements by MRI, CT or ultrasound. The effect existed, but it was small.

Putting the three together: part of the lean mass increase measured on scales and by bioimpedance is water inside the muscle, and the gain in actual muscle tissue is real but modest. Creatine amplifies training; it does not replace it.

Why the response varies

Not everyone responds the same way. In the 2022 meta-analysis, men gained more lean mass with creatine than women, and in the 2023 one the effect was slightly larger in younger than in older adults. Part of the variation probably comes from how much creatine a person already has in their muscle from their usual diet: people who eat little meat and fish tend to start from smaller stores.

It is also worth separating two effects that are often confused. In the first weeks, weight commonly goes up a little, because the muscle stores more water along with creatine. This is not fat or puffiness under the skin. The gain in muscle tissue, when it happens, appears over weeks of training, and that is what imaging measurements can separate.

Creatine is not a hormone

A common mix-up in the gym is to put creatine and anabolic steroids on the same shelf. They are different things. Creatine is a substance the body already makes and that exists in food; it does not act on the androgen receptor and, in the 2025 trial, did not change testosterone or DHT. Anabolic steroids are hormones or derivatives of them.

Is creatine bad for the kidneys?

In healthy people, studies do not show that. The 2025 meta-analysis in BMC Nephrology pooled 21 studies, 12 of them with 440 participants in the main analysis. Creatine was associated with a small rise in blood creatinine, but the glomerular filtration rate, a more direct measure of kidney function, did not change significantly. The authors attribute the rise in creatinine to the metabolism of creatine itself.

This has an important practical consequence: someone who takes creatine may have a creatinine result above the reference range without any kidney problem. Always tell your doctor, who can use other tests to confirm. Anyone who already has kidney disease is in a different situation and needs medical guidance before any supplement.

What about hair loss?

The fear came from a 2009 study of 20 university rugby players, which measured an increase in dihydrotestosterone (DHT), a hormone linked to male-pattern baldness. That study did not measure hair. In 2025, a randomised trial tested the question directly: 45 men aged 18 to 40 who did weight training received creatine or placebo for 12 weeks. There was no difference between groups in DHT, testosterone, or hair density, number of follicular units and hair thickness.

The study is small, short and only in young men, so the evidence is level C. But it is the best answer available, and it did not confirm the fear. If you have a strong family history of baldness and this question weighs on you, take it to a dermatologist, who can assess your case.

Beyond muscle: brain and ageing

Creatine is also studied for cognition, short sleep and ageing. The results are more mixed than for muscle. In older people, strength training combined with good nutrition remains the foundation for preserving muscle mass.

Product quality and safety

Like any supplement, creatine depends on where it comes from. Prefer products registered with your country's health authority and be wary of formulas that mix creatine with stimulants or promise hormonal effects. The 2017 International Society of Sports Nutrition position stand considered creatine safe and well tolerated in healthy people in the short- and long-term studies it reviewed.

How to track it

If you use or are thinking of using creatine, a baseline of creatinine, urine test and any other markers your doctor requests gives you a reference to compare against later. Tell whoever reads your results that you take creatine.

Frequently asked questions

Sources

1. Kreider RB et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. J Int Soc Sports Nutr, 2017;14:18. doi.org/10.1186/s12970-017-0173-z · Evidence D
2. Lanhers C et al. Creatine supplementation and upper limb strength performance: a systematic review and meta-analysis. Sports Med, 2017;47(1):163-73. doi.org/10.1007/s40279-016-0571-4 · Evidence A
3. Desai I et al. The effect of creatine supplementation on resistance training-based changes to body composition: a systematic review and meta-analysis. J Strength Cond Res, 2024;38(10):1813-21. doi.org/10.1519/JSC.0000000000004862 · Evidence A
4. Delpino FM et al. Influence of age, sex, and type of exercise on the efficacy of creatine supplementation on lean body mass: a systematic review and meta-analysis of randomized clinical trials. Nutrition, 2022;103-104:111791. doi.org/10.1016/j.nut.2022.111791 · Evidence A
5. Burke R et al. The effects of creatine supplementation combined with resistance training on regional measures of muscle hypertrophy: a systematic review with meta-analysis. Nutrients, 2023;15(9):2116. doi.org/10.3390/nu15092116 · Evidence A
6. Naeini EK et al. Effect of creatine supplementation on kidney function: a systematic review and meta-analysis. BMC Nephrol, 2025. doi.org/10.1186/s12882-025-04558-6 · Evidence A
7. Lak M et al. Does creatine cause hair loss? A 12-week randomized controlled trial. J Int Soc Sports Nutr, 2025. doi.org/10.1080/15502783.2025.2495229 · Evidence C
8. van der Merwe J, Brooks NE, Myburgh KH. Three weeks of creatine monohydrate supplementation affects dihydrotestosterone to testosterone ratio in college-aged rugby players. Clin J Sport Med, 2009;19(5):399-404. doi.org/10.1097/JSM.0b013e3181b8b52f · Evidence C