Creatine monohydrate has a good safety profile in healthy adults, but that doesn't mean it's right for everyone. There are conditions in which taking the supplement is contraindicated or possible only under the supervision of a doctor. The editors explain who should avoid creatine and why.
Where do the restrictions come from
Most creatine safety studies have been conducted on healthy people between the ages of 18 and 40-50. It is for this group that the position of ISSN (2017) and the review by Antonio et al. (2021) conclude that there is no clinically significant harm at recommended doses.
For other groups — people with chronic diseases, pregnant women, children and teenagers — the data is much less. Lack of evidence of harm in such a situation does not equal evidence of safety. Therefore, the principle of caution applies to them: admission only according to the doctor's decision.
It is also important to understand that creatine is a dietary supplement, not a drug. Its production is less strictly controlled than in pharmaceuticals, and the risk of imprecise composition or impurities must be considered separately from the properties of the substance itself.
Below we divided the restrictions into absolute (when it is better to refuse creatine without discussion) and relative (when the decision is made individually with the doctor).
| Situation | Restriction type | What to do |
|---|---|---|
| Chronic kidney disease, reduced GFR | Contraindications without consultation with a nephrologist | Do not take without medical advice |
| One kidney, kidney transplantation | Relative, high caution | Only by doctor's decision |
| Diabetes mellitus, hypertension with kidney damage | Relative | Assess kidney function |
| Use of nephrotoxic medicines | Relative | Discuss with the doctor |
| Pregnancy and breastfeeding | Insufficient data | Do not take without a doctor |
| Children and adolescents | Insufficient data | Only by medical decision |
| Bipolar disorder | Relative | Psychiatrist consultation |
| Allergy to product components | Contraindications | Choose another product |
Kidney diseases and risk factors
The kidneys are the main organ discussed in the context of creatine. Creatine in the body turns into creatinine, which is excreted in the urine. In healthy people, this does not pose a problem, but with reduced kidney function, any additional load is undesirable, and safety data in this group is limited.
Isolated clinical cases of kidney function deterioration with creatine intake have been described, mostly in people who already had kidney disease or were taking other potentially kidney-damaging substances. These cases do not prove a causal relationship, but are a sufficient signal for caution.
There is also a small observational report of a young man with a single kidney (Gualano et al., 2010) in whom a short course of creatine did not change the measured glomerular filtration rate. However, a single case cannot be the basis for general recommendations.
The risk group includes people with diabetes, long-term uncontrolled hypertension, polycystic kidney disease, urolithiasis in the anamnesis, as well as those who have previously detected protein in the urine. Before taking creatine, they should check their kidney function and discuss the feasibility of the supplement with their doctor.
Separately, we will remind you about the tests: creatine increases creatinine in the blood, which can distort the calculation of GFR. It is especially important for people under the supervision of a nephrologist to report supplements so that the doctor does not draw false conclusions.
Medicines and concomitant conditions
Few direct dangerous interactions of creatine with drugs have been described, but the logic of caution is obvious: if the drug can burden the kidneys, adding another factor without control is undesirable. Such drugs include, in particular:
- nonsteroidal anti-inflammatory drugs (ibuprofen, diclofenac, etc.) with long-term use;
- diuretics, especially in combination with dehydration;
- some antibiotics (aminoglycosides) and antiviral agents;
- immunosuppressants, in particular cyclosporin;
- lithium preparations.
Special attention should be paid to people with bipolar disorder. In the medical literature, cases of episodes of mania against the background of taking creatine in patients with affective disorders are described. Evidence is not enough to talk about regularity, but consultation with a psychiatrist before admission in such a situation is mandatory.
People with severe liver disease also belong to the group for which there are insufficient data and the decision must be made by the doctor. This also applies to any situation when a person takes several drugs at the same time.
If you are not sure if you are at risk, the easiest step is to show your doctor or pharmacist the ingredients of the supplement and the list of your medications.
Pregnancy, feeding, adolescents
Pregnancy and breastfeeding are periods when any supplement should be considered with the utmost caution. Although the potential role of creatine for the fetus and placenta is debated in scientific circles, clinical studies in pregnant women are insufficient. Therefore, without a doctor's prescription, creatine is not recommended during this period.
Regarding children and teenagers, the situation is similar. There are studies of creatine in young athletes and in medical contexts, such as congenital disorders of creatine synthesis, which are treated under the supervision of specialists. But general recommendations for healthy teenagers who are just exercising are given by specialized organizations with great caution.
The ISSN position statement allows that creatine can be considered for adolescents who are seriously involved in sports, follow a balanced diet and understand the correct use of supplements - under the supervision of parents and professionals. The editors believe that technology, sleep and nutrition should be the priority for teenagers, not supplements.
Elderly people do not belong to the group with contraindications - on the contrary, there is convincing data for them about the benefits of strength training. But with age, kidney disease and medication are more common, so it's wise to assess kidney function before starting.
Sports and household restrictions
In addition to medical restrictions, there are situations when creatine is simply not appropriate. For example, for athletes of weight categories before weighing, a sharp increase in weight due to water retention can prevent them from "fitting" into the category.
Taking creatine against the background of aggressive dehydration, for example during "weight loss" by sauna or diuretics, is undesirable not because of creatine itself, but because of the general danger of such practice for the kidneys and heart.
For people who have a sensitive stomach or irritable bowel syndrome, creatine is not contraindicated, but it is advisable to start with small doses and choose a micronised powder.
Finally, athletes undergoing doping control should remember that creatine is not on the WADA Prohibited List, but a contaminated supplement may contain banned substances. Choose products with independent batch testing.
Editorial conclusions
Creatine monohydrate is safe for most, but not all, healthy adults. People with kidney disease should not take it without consulting a nephrologist, and those with risk factors or taking nephrotoxic medications should be consulted first.
Pregnancy, breast-feeding and adolescence — situations for which there is a lack of data, therefore admission is possible only by medical decision. People with bipolar disorder should discuss creatine with a psychiatrist.
Always tell your doctor about taking creatine before the tests, because it affects the creatinine level.
For the full picture, also read "Side effects of Creatine monohydrate", "How to take Creatine monohydrate: dosage, time of administration, duration" and "Myths about Creatine monohydrate".
List of used literature
- Kreider RB, Kalman DS, Antonio J, 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.
- Antonio J, Candow DG, Forbes SC, et al. Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show? J Int Soc Sports Nutr. 2021;18(1):13.
- Poortmans JR, Francaux M. Long-term oral creatine supplementation does not impair renal function in healthy athletes. Med Sci Sports Exerc. 1999;31(8):1108â1110.
- Gualano B, Ferreira DC, Sapienza MT, et al. Effect of short-term high-dose creatine supplementation on measured GFR in a young man with a single kidney. Am J Kidney Dis. 2010;55(3):e7âe9.
- Maughan RJ, Burke LM, Dvorak J, et al. IOC consensus statement: dietary supplements and the high-performance athlete. Br J Sports Med. 2018;52(7):439â455.
- World Anti-Doping Agency. World Anti-Doping Code International Standard: Prohibited List 2026. Montreal: WADA; 2026.
