Few supplements carry as many warnings as creatine: that it damages the kidneys, causes hair loss, leads to concerning fluid retention, or may increase blood pressure.
But many of these claims combine findings from specific studies, incorrect interpretations, and recommendations that have been repeated for years without much context.
In this guide, we review the main creatine contraindications, its possible side effects, and some of the most widespread myths, distinguishing between what is scientifically supported and the situations in which it may be advisable to consult a healthcare professional before using it.
Myth: “creatine damages the kidneys”
This is probably one of the most common concerns about creatine.
Part of this concern has to do with creatinine, a substance commonly used as a marker when assessing kidney function.
Creatine supplementation may influence creatine and creatinine concentrations, so a change in this marker should not be interpreted in isolation as evidence of kidney damage.
Research carried out in healthy people has extensively studied kidney function during creatine supplementation and has not established that its use under the conditions studied causes kidney damage.
AESAN also states in its assessments that creatinine may be elevated in people who consume creatine without this necessarily implying kidney failure.
This does not mean that the situation is identical for everyone.
In people with pre-existing kidney disease, impaired kidney function, or medical monitoring for this reason, it is especially important to consult a healthcare professional before using creatine supplements.
Can creatine affect a blood test?
It may modify some parameters related to creatine metabolism.
Therefore, if you consume creatine and are going to have a blood test, it is advisable to inform the healthcare professional that you are taking this supplement.
This allows the results to be interpreted in the context of the complete picture and prevents conclusions from being drawn based solely on an isolated marker.
This does not necessarily mean that you need to stop using it before every test: any decision of this kind should depend on the instructions of the professional requesting the test.
Myth: “creatine causes hair loss”
The relationship between creatine and baldness became particularly popular following a small study conducted years ago in rugby players.
That study observed changes in certain hormonal markers, but it did not directly assess hair loss or demonstrate that creatine caused alopecia.
From there, an association arose that continues to appear on social media and forums.
So far, the available evidence does not allow a causal relationship to be established between creatine supplementation and hair loss.
Therefore, saying directly that “creatine causes baldness” goes far beyond what the available studies allow us to conclude.
Reality with nuances: creatine may increase muscle water content
There is a real basis behind this myth.
Creatine supplementation may modify the water content associated with muscle tissue, especially during the early stages of certain protocols.
This may translate into an increase in body weight in some people.
However, this should not automatically be confused with generalized fluid retention or with the usual concept of feeling “bloated.”
In addition, the response may vary between individuals and depend on the protocol used.
Can this weight gain matter?
For most people, a small variation in body weight may not have much practical significance.
However, it can be important in sports with weight categories, where a few hundred grams or a weight change close to a competition may influence sporting strategy.
In these cases, supplementation should be planned taking the competition schedule into account and, when appropriate, together with a professional specializing in sports nutrition.
Myth: “creatine raises blood pressure”
The available research does not allow us to establish that creatine alone causes an increase in blood pressure in healthy people.
This does not mean that it can be used as a treatment or that a person with hypertension should modify their supplementation on their own.
If diagnosed hypertension, cardiovascular disease, or drug treatment related to blood pressure is present, it is advisable to assess the individual context with a healthcare professional.
Myth: “it causes cramps and dehydration”
For years, it has been repeated that creatine could increase the risk of muscle cramps or dehydration during exercise.
However, the available evidence has not established that creatine supplementation systematically increases these problems in healthy people who use it in the contexts studied.
In any case, hydration remains important regardless of whether or not creatine is used.
Fluid requirements depend on factors such as exercise intensity, duration, ambient temperature, sweating, and individual characteristics.
Myth: “you have to stop taking creatine before surgery”
There is no universal rule requiring everyone to stop taking creatine before any surgical procedure.
What is advisable is to inform the doctor, anesthesiologist, or healthcare team of all medications, dietary products, and supplements being used before an intervention.
The professional will decide whether any of them should be temporarily discontinued depending on the type of procedure and individual circumstances.
You should not decide on your own what to continue or stop before surgery.
What are the side effects of creatine?
When adverse effects occur during creatine use, one of the most frequently described problems is gastrointestinal discomfort, especially when large amounts or certain protocols are used.
Symptoms such as a feeling of heaviness, digestive discomfort, or diarrhea may occur in some people.
Tolerance is individual and may also depend on factors such as the amount used in a single dose.
If symptoms are persistent or significant, it is advisable to stop using the product and consult a healthcare professional.
Does creatine affect the liver?
Liver function has also been analyzed in studies on creatine supplementation.
In healthy populations, the available evidence has not consistently established liver abnormalities attributable to creatine under the conditions studied.
However, people with pre-existing liver disease or who are under medical supervision should consult a healthcare professional before using dietary supplements.
Who should consult before taking creatine?
Although creatine has been extensively studied, there are situations in which it is particularly reasonable to consult a professional before starting.
These include:
- Diagnosed kidney disease or impaired kidney function.
- Liver disease.
- Pregnancy or breastfeeding.
- Drug treatments requiring monitoring.
- Relevant chronic conditions.
- Minors.
- People undergoing specific medical monitoring.
- Situations in which there is a medical indication to monitor certain blood-test parameters.
Consulting under these circumstances does not necessarily mean that creatine is prohibited. It means that the decision should be individualized.
Creatine and medications: can there be interactions?
The answer depends on the medication and the clinical situation.
It is not appropriate to establish a universal list of “compatible” or “incompatible” medications without knowing the complete treatment.
If a person regularly takes medication, especially if kidney, cardiovascular, or liver disease or another chronic condition is present, the most appropriate course is to consult a doctor or pharmacist before adding a supplement.
We explore this topic in greater depth in our guide on creatine and medication interactions.
Is creatine safe for adolescents?
Research on creatine in minors is less extensive than the research available in adults.
Therefore, the same recommendation for use given to adults should not automatically be applied to adolescents.
In minors, the use of sports supplements should be assessed individually and supervised by a professional, especially if they are intended to be used for extended periods.
Are regular blood tests necessary?
There is no universal recommendation stating that every healthy person who consumes creatine should have blood tests solely for this reason.
This does not mean that blood tests may not be indicated for other reasons.
If there is already medical monitoring, a pre-existing illness, drug treatment, or a relevant medical history, the healthcare professional may establish whatever monitoring they consider necessary.
Is it dangerous to take creatine for a long time?
The safety of creatine has been the subject of numerous studies and assessments.
However, it would be too categorical to claim that every protocol, amount, or duration is automatically safe for every person.
The available evidence provides substantial information about its use in healthy populations, but safety should always be interpreted taking into account the amount, duration, individual characteristics, and conditions of use.
AESAN has specifically assessed the use of creatine monohydrate in dietary supplements at a maximum daily amount providing 3 g of creatine.
Can creatine cause acne?
Currently, there is insufficient evidence to establish that creatine supplementation is a direct cause of acne.
The fact that a person notices skin changes while using creatine does not in itself demonstrate a causal relationship.
Acne can be influenced by numerous hormonal, genetic, environmental, and lifestyle-related factors.
Can creatine affect people with cardiovascular problems?
A universal recommendation should not be established.
A healthy person and a person with diagnosed cardiovascular disease are different contexts.
If heart disease, hypertension, cardiovascular treatment, or specialist monitoring is present, it is advisable to consult a professional before starting any supplementation, including creatine.
Creatine, pregnancy, and breastfeeding
The information available for these populations is much more limited than for healthy adults.
For this reason, during pregnancy and breastfeeding, it is not appropriate to start supplementation on your own.
Any decision should be assessed with a healthcare professional who can analyze the individual context.
Why are there still so many myths about creatine?
Some of these beliefs arose when there was much less research than there is today.
This is compounded by confusion between associations and causation.
For example:
creatine → may modify creatinine → “it damages the kidney”
or:
a study observes a hormonal marker → “it causes baldness”
These are simplifications that remove important steps from scientific reasoning.
Therefore, when reading any claim about creatine side effects, it is worth asking what the cited research actually studied and whether the observed result allows that conclusion to be drawn.
Frequently asked questions about creatine contraindications
Is creatine bad for the kidneys?
In healthy people, the available evidence does not establish that creatine supplementation causes kidney damage under the conditions studied.
However, people with kidney disease or previous abnormalities should consult a healthcare professional before using it.
Can it increase creatinine?
Yes, creatine use may influence this marker.
Therefore, it is important to inform your doctor that you use creatine when you have a blood test, so that the results can be interpreted correctly.
An increase in creatinine does not automatically mean that kidney damage is present.
Does creatine cause baldness?
The available evidence does not allow us to establish that creatine causes hair loss.
The association mainly comes from indirect interpretations of studies that did not demonstrate supplementation-caused alopecia.
Does creatine cause fluid retention?
It may modify the body’s water content, especially that associated with muscle tissue.
This may cause changes in body weight, but it should not automatically be interpreted as problematic fluid retention.
Can it cause digestive discomfort?
Yes, some people may experience gastrointestinal discomfort.
Tolerance may depend on the amount used and the protocol.
Do I have to stop taking it if I am going to have a blood test?
Not necessarily.
Inform the healthcare professional that you use creatine and follow their instructions before modifying or stopping supplementation.
Do I have to stop taking it before surgery?
There is no universal rule applicable to all procedures.
Inform the medical team of all supplements and medications you use and follow their instructions.
Does creatine affect the liver?
In healthy populations, the available evidence has not consistently established liver damage attributable to its use in the contexts studied.
If pre-existing liver disease is present, consult a professional.
Is it safe for adolescents?
The evidence is more limited than in adults.
For this reason, its use in minors should be assessed and supervised by a professional.
Is it necessary to take breaks from creatine for safety reasons?
There is insufficient evidence to establish that everyone should take periodic breaks solely because of a supposed “acclimatization” phenomenon.
The amount, duration, and individual circumstances should be assessed within the context of use.
Does creatine cause acne?
Currently, there is no sufficiently established causal relationship between creatine and acne.
Can it affect body weight?
Yes, some people may experience weight changes related, among other factors, to modifications in muscle water content.
This may be particularly important in sports organized by weight categories.
To wrap up
When discussing creatine contraindications, it is important to separate myths from real precautions.
The available evidence does not support many of the most widespread claims, such as the idea that creatine automatically causes kidney damage, baldness, dehydration, or liver problems in anyone who uses it.
That also does not mean that it is an appropriate supplement for everyone without exception.
People with kidney or liver disease, those who are pregnant or breastfeeding, minors, users of certain medications, or patients with chronic diseases should assess their individual situation with a healthcare professional.
The key is not to consider creatine “dangerous” or “completely harmless,” but to interpret the evidence within the appropriate context and use dietary supplements according to their conditions of use.