In a nutshell
What is creatine and why is it taken?
Creatine is a substance produced by the body that primarily serves as an energy store in the muscles for short, intense exertion. The body produces part of it itself in the liver, kidneys, and pancreas; another part comes from food, especially meat and fish. Creatine monohydrate is usually used as a dietary supplement, as it is the most well-researched and affordable form available. The goal of supplementation is to saturate muscular creatine and phosphocreatine stores, which can support short-term strength and performance during repeated intense exertion.
Precisely because creatine is so widespread, many safety concerns circulate at the same time. This article assesses which side effects are actually proven by studies, which fears have turned out to be myths, and who should be cautious when taking it.
The most common, actually proven side effects
Scientific literature primarily describes two types of complaints with creatine monohydrate, both usually mild and temporary:
| Complaint | What happens | How common / when |
|---|---|---|
| Water retention | Creatine binds water in the muscle cells, which can appear as slight weight gain on the scale and visually. | Mainly in the first or second week, especially during a high-dose loading phase. |
| Gastrointestinal issues | Bloating, diarrhea, abdominal pain, or nausea, usually caused by single doses that are too high or insufficient fluid intake. | Mainly with single doses over 5g; rarer when portions are spread out. |
| Muscle cramps | Occasionally reported, but controlled studies show no increased risk of cramping compared to placebo. | Rare; causality not scientifically clearly proven. |
The position paper of the International Society of Sports Nutrition (ISSN) summarizes the safety data as follows: In the dosages examined in studies, predominantly mild gastrointestinal side effects occur; serious side effects have not been documented in reliable frequency in healthy individuals, even over several years of use.
Myth 1: Does creatine damage the kidneys?
Where does this concern come from?
However, this rise generally only reflects the increased creatine turnover, not an actual deterioration in kidney function. Randomized studies and review articles in healthy individuals find no evidence of a deterioration in kidney function, as measured by, for example, the glomerular filtration rate or other kidney function markers, at standard daily dosages of 3 to 5g or during short-term loading phases. Observations over multi-year periods of use in healthy athletes also show no abnormal kidney values.
An important caveat remains: these data apply to people with healthy kidneys. For those with pre-existing kidney disease, the data is significantly thinner, which is why in this case, creatine should only be taken after consulting a doctor.
Myth 2: Does creatine cause hair loss?
Where does this concern come from?
This single study was frequently cited in the following 15 years, but it was not specifically re-examined for a long time. That changed in 2025: a randomized, placebo-controlled study, published in the Journal of the International Society of Sports Nutrition, tested for the first time directly whether creatine affects the health of hair follicles.
| Study parameters | Detail |
|---|---|
| Participants | 45 strength-trained men (18–40 years old), 38 completed the study |
| Design | Randomized, placebo-controlled: 5g creatine monohydrate/day vs. 5g maltodextrin/day |
| Duration | 12 weeks |
| Measured | DHT levels, DHT-to-testosterone ratio, hair growth parameters |
| Result | No significant differences between the creatine and placebo groups in DHT, DHT/testosterone ratio, or hair growth |
This study, published in 2025, thus provides the most direct refutation of the hair loss myth to date: neither hormone levels nor actual hair growth parameters differed between the groups. While a residual risk for individuals with an existing genetic predisposition to androgenetic hair loss cannot be completely ruled out by a single study, the burden of proof now clearly speaks against a relevant connection.
Expert Perspectives & Protocol Breakdown
The International Society of Sports Nutrition, led by Richard Kreider, pursues a broad consensus approach in its position paper: dozens of individual studies on safety, kidney values, gastrointestinal tolerance, and long-term use are combined into an overall assessment, resulting in the conclusion that creatine monohydrate is one of the most well-supported dietary supplements for healthy adults.
In contrast, the randomized study published in the same journal in 2025 follows a targeted, hypothesis-driven approach: instead of providing a broad safety balance, it addressed a single question mark that had remained unanswered since 2009—specifically whether the DHT increase measured by van der Merwe, Brooks, and Myburgh actually leads to hair loss. For consumers, the juxtaposition means the following: the broad ISSN consensus provides the general safety assessment, while the targeted 2025 study answers the only concrete detail question that had remained open from a 16-year-old individual study.
Dosage and how to reduce the risk of side effects
Practical tip
| Approach | Dosage | Side effect risk |
|---|---|---|
| Loading phase (classic) | approx. 20 g/day, divided into 4 portions of 5 g, for 5–7 days | Higher: more frequent gastrointestinal issues and increased water retention |
| Maintenance dose | 3–5 g/day, long-term | Low |
| Direct start without loading phase | 3–5 g/day from day 1 | Low, saturation takes longer (approx. 3–4 weeks) |
Interactions and who should be cautious with creatine
For most healthy adults, creatine monohydrate is considered well-researched and well-tolerated at the mentioned dosages. However, caution and prior medical consultation are advisable in the following cases:
- Existing or past kidney disease, as the safety data is significantly thinner here than for healthy kidneys.
- Concurrent use of kidney-relevant medications, such as certain painkillers (NSAIDs) or nephrotoxic agents, due to a possible additive burden on the kidneys.
- During pregnancy and breastfeeding, as there is insufficient safety data for targeted supplementation.
- For children and adolescents, for whom creatine supplementation is not sufficiently studied and not generally recommended.
Those following a diet with significantly reduced fluid intake or who are prone to migraines or water retention should combine intake with sufficient fluids and reduce the dose if necessary.
Who is creatine still useful for?
For healthy adults without the above-mentioned risk factors, creatine monohydrate is one of the most well-proven dietary supplements in the sports sector. Those who want to minimize mild, usually temporary side effects can skip a high-dose loading phase, divide the daily dose into two portions if needed, and drink enough water.
Frequently asked questions about creatine side effects
What are the real side effects of creatine?
The main documented side effects are temporary water retention and, with high single doses, gastrointestinal issues such as bloating or diarrhea. Both can usually be avoided with a moderate dosage of 3 to 5 g per day and sufficient fluid intake.
Does creatine damage the kidneys?
In healthy individuals, randomized studies and review articles show no deterioration in kidney function at typical dosages, even after several years of use. The occasionally observed increase in creatinine levels reflects the increased creatine turnover, not necessarily kidney damage. In cases of existing kidney disease, intake should be clarified with a doctor beforehand.
Does creatine cause hair loss?
A randomized, placebo-controlled study published in 2025 with 45 strength-trained men found no significant differences in DHT levels, DHT-to-testosterone ratio, or hair growth parameters compared to placebo after 12 weeks of creatine supplementation. The myth stems from a single, small study from 2009, which measured a slight increase in DHT—within the normal range—but did not observe any actual hair loss.
Should I do a loading phase?
It is not necessary. A loading phase (approx. 20 g/day) saturates muscle stores faster, but increases the risk of gastrointestinal issues and water retention. A direct start with 3 to 5 g daily reaches saturation more slowly but is better tolerated.
Who should not take creatine?
Restraint or prior medical consultation is recommended for those with existing kidney disease, those taking kidney-relevant medications, during pregnancy and breastfeeding, and for children and adolescents, as there is insufficient safety data for these groups.
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References & Scientific Citations
- Kreider, R. B., Kalman, D. S., Antonio, J. et al. (2017). 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 14:18
- van der Merwe, J., Brooks, N. E. & Myburgh, K. H. (2009). Three Weeks of Creatine Monohydrate Supplementation Affects Dihydrotestosterone to Testosterone Ratio in College-Aged Rugby Players, Clinical Journal of Sport Medicine 19(5):399-404
- Randomized controlled trial (2025). Does Creatine Cause Hair Loss? A 12-Week Randomized Controlled Trial, Journal of the International Society of Sports Nutrition
These products are dietary supplements, not medicines. This article does not replace medical advice.
