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Creatine
what the evidence shows
The short answer: creatine monohydrate is one of the most studied supplements. Together with strength training, it slightly improved strength and short, intense efforts compared with placebo; lean mass goes up, partly from water, and muscle measured directly grows only a little. In healthy people no kidney damage has been seen (creatinine in blood tests goes up, which does not mean damage), and it has not been shown to make your hair fall out. A loading phase is not needed. If you have kidney disease, take medication, are pregnant or are under 18, check first.
Reverfit does not sell supplements or recommend any brand. Every figure links to its study and says how strong the evidence is.
1. What it is
Weak evidence · experts or few studies Almost all the creatine in the body (around 95%) is in muscle, mostly as phosphocreatine, which quickly restores energy during short efforts. A normal diet provides 1–2 g a day, mainly from meat and fish, and the body makes the rest (ISSN 2017; Brosnan 2011). People who do not eat meat or fish make almost all of it themselves.
2. Strength and short efforts
- Strong evidence · meta-analyses A small but consistent improvement in leg strength in efforts of less than 3 minutes (Lanhers 2015, 60 trials) and in arm and chest strength (Lanhers 2017, 53 trials), especially in repeated efforts of 30 seconds or less; it was not seen in running or swimming (Branch 2003).
- Strong evidence · meta-analyses In kilos, with training: across 69 trials, about 1.4 kg more on the bench press and 5.6 kg more on the squat than with placebo (Kazeminasab 2025). In that same work, when split by sex, the squat, jump and power improved in men and not in women. Another meta-analysis in people under 50 gives larger figures, with very few women (Wang 2024).
- Weak evidence · experts or few studies It is among the few supplements with good evidence according to the consensus of the International Olympic Committee (IOC 2018) and the Australian Institute of Sport (AIS, group A).
3. More muscle or more water?
- Strong evidence · meta-analyses Lean mass goes up, but only with training: +1.1 kg with strength training and nothing without exercise (Delpino 2022, 35 trials). By sex, +1.46 kg in men and +0.29 kg in women, which was not significant there. That lean mass includes water.
- Strong evidence · meta-analyses Muscle measured directly (MRI, ultrasound) grew very little, without it being certain that there is an effect (Burke 2023, 10 trials).
4. Older adults and women
- Strong evidence · meta-analyses In older adults who do strength training, more lean mass (+1.4 kg) and a bit more strength (Chilibeck 2017, 22 trials). In another meta-analysis of people over 60, strength improved and muscle mass did not significantly, and it does not apply to frail people (Yao 2026).
- Strong evidence · meta-analyses There are fewer studies in women: in older women, upper-body strength improved (Dos Santos 2021), and in postmenopausal women who trained, some lean mass and leg strength (Naddafha 2026, 7 trials).
5. The doses that have been studied
- Moderate evidence · trials With or without loading you end up in the same place: 20 g a day for 6 days raised muscle creatine by 20%, the same as 3 g a day for 28 days; after stopping, it returns to its usual level within a month (Hultman 1996).
- Weak evidence · experts or few studies The most common amount in studies is 3–5 g a day, and loading is not considered necessary (ISSN 2021). There are no firm conclusions about the time of day (Ribeiro 2021).
- In Spain, the Scientific Committee of AESAN (the Spanish food safety agency) considered up to 3 g of creatine a day in food supplements acceptable for healthy adults (AESAN 2024).
6. Is it safe?
- Strong evidence · meta-analyses Healthy kidneys: across 20 trials, creatinine in blood tests rose by 0.13 mg/dL, with no change in urea (Tsiaras 2026). Kidney filtration calculated from creatinine comes out lower, but measured with a method that does not depend on it (Cr-EDTA) it did not change (De Souza Almeida 2026). If you have blood tests, tell your doctor you take it: creatinine and filtration may look like a problem that is not one. There are no studies longer than a year.
- With kidney disease, there is little data and the safety assessment in Spain is for healthy adults: check first (AESAN 2024; ISSN 2021).
- Weak evidence · experts or few studies Weight and water: with a loading phase (about 20 g a day for 5–7 days) weight usually goes up 1–3 kg, mostly from water. In studies lasting several weeks, more body water was not always seen (ISSN 2021). No more dehydration or cramps have been seen (Dalbo 2008).
- Moderate evidence · trials Hair: the fear comes from a study in 20 players in which the hormone DHT went up, without measuring hair (Van der Merwe 2009). In a 2025 trial neither DHT nor hair changed (Lak 2025, small sample).
- Weak evidence · experts or few studies Under 18s: there are few studies (Jagim 2021). It is not recommended without a professional’s supervision.
7. Brain and mood: still preliminary
- Strong evidence · meta-analyses Memory: a small improvement, with moderate certainty, and the other functions with low certainty (Xu 2024, 16 trials).
- Strong evidence · meta-analyses Depression: an effect below what is clinically relevant and with very low certainty evidence (Eckert 2025). It does not replace any treatment.
8. Vegetarians and vegans
Moderate evidence · trials They start with less creatine in their muscles and, when taking it, gained more creatine and more lean mass than people who ate meat (Burke 2003, 42 people).
9. Which type, and quality
- Monohydrate is the form with solid evidence of effectiveness and safety (Kreider 2022). The ethyl ester did worse (Spillane 2009) and «buffered» creatine was no better (Jagim 2012).
- Impurities: products have been found with traces of dicyandiamide and metals (ISSN 2021); independent testing seals help.
- Anti-doping: creatine is not prohibited, according to the US Anti-Doping Agency, which recommends certified products because of contaminants (USADA).
10. What EU law allows to be said
In the EU, a food or supplement may only attribute properties to creatine with these authorized claims and under these conditions. We quote them as they are:
- «Creatine increases physical performance in successive bursts of short-term, high intensity exercise.» Only in foods that provide 3 g of creatine a day, stating that the effect is obtained with that amount, and aimed at adults doing high-intensity exercise (Regulation (EU) 432/2012).
- «Daily creatine consumption can enhance the effect of resistance training on muscle strength in adults above the age of 55 years.» With 3 g a day and resistance training at least three times a week for several weeks, at 65–75% of one-repetition maximum (Regulation (EU) 2017/672).
If you see a product that promises more than this, such as «burns fat» or «guaranteed muscle gain», that claim is not authorized.
Frequently asked questions
Does creatine work?
It is one of the supplements with the most evidence. Combined with strength training, in meta-analyses of dozens of trials it slightly improved strength and short, intense efforts compared with placebo. Lean mass goes up, partly from water, and muscle measured directly grows only a little. The effect is small and varies from person to person.
Is creatine bad for your kidneys?
No harm has been seen in healthy people: across 20 trials, creatinine in blood tests rose slightly (0.13 mg/dL), with no change in urea. Kidney filtration calculated from creatinine comes out lower, but measured with a method that does not depend on it, it did not change. That rise in creatinine does not mean damage, but you should tell your doctor when you have blood tests. There are no studies longer than a year. If you have kidney disease, check before taking it.
Does creatine make your hair fall out?
It has not been shown. The idea comes from a 2009 study in 20 rugby players in which a hormone (DHT) went up, but hair was not measured. In a 2025 trial with 5 g a day for 12 weeks, neither that hormone nor hair density or thickness changed.
Do you need a loading phase with creatine?
No. In a classic study, 20 g a day for 6 days raised muscle creatine as much as 3 g a day for 28 days: loading just gets there sooner. The International Society of Sports Nutrition considers loading unnecessary.
Does creatine cause water retention?
At the start, especially with loading, weight usually goes up 1–3 kg, largely from water inside the muscle. It has not been found to cause dehydration or more cramps.
What does the law say about creatine?
In the EU, a food or supplement may only say that «creatine increases physical performance in successive bursts of short-term, high intensity exercise» if it provides 3 g a day and is aimed at adults doing high-intensity exercise (Regulation 432/2012), and there is another claim for people over 55 who do strength training (Regulation 2017/672).
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