Creatine side effects and risks

10. Is creatine safe for women, children or the elderly?
11. Creatine risks and side effects?
12. Long-term consequences of creatine use?
13. Does creatine cause cancer?
14. Can creatine help those with Muscular Dystrophy?

Understandably, “What are creatine’s side effects?” is my most frequently asked question surrounding creatine supplementation. It was the hallmark question when we first launched the Creatine Information Center (1998) and continues to be a major concern of athletes (profession, amateur, young and old) until the present day. In fact, we originally went public in 1998 in an attempt to balance the huge amount of misinformation then circulating about creatine. The broad-based confusion concerning creatine supplementation is likely the reason that its potential side effects are such a concern to the health and fitness community.

I am of the belief that creatine supplementation is a relatively safe practice if undertaken with moderation and within accepted guidelines, but as anything in life, going to extremes can unveil “unexpected” consequences; side effects. The limits and boundaries of creatine supplementation have to understood and respected.

Unfortunately, there is a lot of wrong information circulating on the internet and popular press. It is amazing, troubling actually, how fast bad information can be perpetuated and disseminated with utmost authority. The main focus of some “creatine authorities” is to sell nutritional supplements and hence…, they are a bit less cautious in prescribing creatine doses or in endorsing products containing relatively unstudied additives. They take refuge behind reputed scientific studies indicating that creatine use (within specified guidelines) is a relatively safe practice and then allow themselves to push the boundaries a bit further outside of what has been scientifically validated.

There is one certainty, however, a “More is Better” approach with regards to creatine supplementation is pointless. Quite frankly, supplementing your diet with exorbitant doses will be a waste of creatine, money as well as places an undue stress on your system.

Creatine: A practical guide explicitly gives dosing protocols used in peer-reviewed scientific studies and explains their best application for particular cases. Creatine: A practical guide also explains what precautions should be taken while supplementing with creatine monohydrate.

While certain classes of side effect have unequivocally been linked to creatine consumption, others have not. I will begin this section by describing those side effects which have been clearly linked to creatine use and end with a discussion of the side effects sometimes attributed to creatine consumption, but largely unexplained based on our current knowledge of creatine’s accepted mechanisms of action, and give some possible explanations.

Substantiated side effects arising from creatine use nearly exclusively involve the propensity for creatine “monohydrate” salt to retain water. Scientifically speaking, creatine exerts an osmotic pressure that pulls water within any cell (muscle cell) or body compartment (intestine) where it has become highly concentrated. For athletes in some sports this may be a desired outcome of creatine supplementation (see Muscle Volumizing). On the other hand, if NOT compensated for with adequate fluid intake, other body tissues may be deprived of much needed fluids, especially during strenuous exercise (see Dehydration). It is thus very important that you remain well hydrated while supplementing. Drink at least 30-60 milliliters (1-2 ounces) of water daily per kilogram (2.2 pounds) of body weight while supplementing. Other possible side effects may have to do with the body’s ability, or rather, inability to clear creatine and its associated by-products from the body.

Muscle Volumizing:

An increase in body weight is the most widely accepted side effect attributed to creatine use. As much as 3 kilograms (6.6 pounds) of added body weight have been reported during the first weeks of supplementation. Such a rapid increase in body mass is almost certainly due to the movement of water from the blood stream into skeletal muscle; it is simply too rapid to be due to an increase in “dry” muscle mass (proteins). This form of muscle growth is known as Muscle Volumizing because our muscles literally inflate with water, increasing their overall volume.

Some athletes (bodybuilders and powerlifters, for example) may consider Muscle Volumizing a desirable consequence of creatine supplementation. On the other hand, other types of athletes (endurance athletes, for instance) may find that muscle volumizing actually interferes with the performance of their respective events. It is easy to imagine how a few extra “kilos” may hinder one’s performance in a marathon. In any case, creatine-based energy production bestows relatively little energetic benefit during endurance events (see “Do all muscles respond to creatine?”).

Later stages of muscle growth, on the other hand, do involve the acquisition of new muscle proteins, but will be smaller in magnitude and more protracted in time when compared to the increase in body mass attributed to Muscle Volumizing. The proportion of gains that persist, moreover, will increase by combining creatine with essential B vitamins and other important nutrients (also see “How does creatine cause muscle growth?”).

The contributions that B vitamins can make to the benefits of creatine supplementation are discussed in Issue 30 of the Creatine Newsletter.


Again, it’s imperative that you remain well-hydrated while supplementing. Adequate hydration is important, since much of your body water follows creatine into skeletal muscle, possibly depriving our remaining tissues of much needed fluid, especially when exercising in hot and humid environments. Down the road this may lead to impaired thermoregulation and subsequent heat exhaustion. This precaution is especially valid in combative sports (wrestling, etc) where athletes strive to make weight before competition. Weight loss under these circumstances is often achieved through fluid restriction, which, in combination with creatine use, could lead to excessive dehydration.

1997 Wrestlers Death Controversy
Hyperthermia and Dehydration

Highlighting this concerns was the controversy over the deaths of three college wrestlers. The deaths occurred independently, at three separate college campuses, on three separate occasions. From the available evidence, it appeared that dehydration, elevated body temperature and excessive weight loss all contributed to their demise. To what degree, however, creatine may have participated in their unfortunate deaths was then hotly debated in the popular press. Later, it was revealed that two of the athletes might not have used creatine after all. USA Today later retracted its original allegation that creatine was implicated in these deaths. Nonetheless, it is imperative to remain well hydrated while supplementing and undertaking extreme measures to lose weight and/or participating in strenuous exercise in hot and humid environments. These incidents have contributed to the National Collegiate Athletic Association (NCAA) imposing stronger restrictions on weight loss protocols among college athletes.

Click here for the US Government’s Department of Health and Human Resource’s Center for Disease Control and Prevention (CDC) official synopsis of the event.

Gastrointestinal Distress:

Gastrointestinal distress is the secondly most common side effect reported. Incidences of stomach cramps, nausea, flatulence, and diarrhea are more commonly reported during the loading phase when greater amounts of creatine are consumed each day. These side effects are principally due to the presence of large quantities of undissolved creatine particles residing within the intestinal compartment. Remember, creatine has the propensity to draw water into the body compartment where it is found. If the body compartment in question is the large intestine, then excessive water absorption may lead to diarrhea and intestinal cramps. These side effects can often be largely circumvented by making sure that creatine is completely dissolved in at least 16 ounces of water (or juice) and never consuming more than the recommended dosing amount (see “How much and when should I take creatine?”).

To circumvent incidences of gastrointestinal distress, micronized and effervescent forms of creatine have been developed. These forms of creatine are more easily absorbed into the blood stream and, hence, have less of a tendency to collect within the intestinal compartment. Downstream the increased solubility of these products this will help evade gastrointestinal complications. You can find out more about the different forms of creatine by reading my Creatine Products Review. Learn the theory behind the formulations of the most popular creatine products on the market. After reading this review, anyone will be able to determine which additives are truly enhancing the properties of a given creatine product, or are merely added to inflate the price and to give a false sense of innovation. This review is normally included as a bonus to those purchasing Creatine: A practical guide. However, you can download an abbreviated version of the Creatine Products Review for free.

The presence of additives or contaminants may also be a source of gastrointestinal discomfort. These days, it seems as if every creatine manufacturer is trying to distinguish their particular product from the rest of the crowd. Each day new marketing twists are appearing with the main objective of making their particular products appear superior to all the rest. As a result more and more extraneous agents are being added to the growing list of creatine products. People who experience gastrointestinal discomfort from creatine may merely be sensitive to these additives and not to the creatine per se. If your particular brand of creatine gives you an upset stomach, switch to a source of pure creatine monohydrate. It’s thus important that you purchase your creatine from a reputable creatine provider.


The large amounts of sugars often consumed with creatine may lead to flatulence, complicate gastric emptying and result in gastric cramps (see “How does creatine get into muscle?”). Mechanistically, certain classes of carbohydrates, particularly when consumed in large quantities, may pass undigested through the small intestine and ultimately collect (nearly intact) in the large intestine. Here, intestinal bacteria decompose the sugar, releasing gas. If sufficiently large amounts of gas are produced to exert pressure within the intestinal compartment, then cramps may ensue. Flatulence is the expelling of this gas.

Fructose and sorbitol are especially notorious in this respect. Therefore, avoid mixing your creatine in juices containing mainly fructose.

Muscle strains, cramps and tears:

These side effects are sometimes reported in chat rooms and in the popular press. As a result, these incidences are sometimes dismissed as anecdotal and unfounded. Similar incidences, although rare, have also been reported during controlled scientific studies. Nevertheless, the validity of these side effects is still being debated in the creatine scientific community. Due to, in great part, to the appearance of scientific studies showing no, or even a positive, effect of creatine over the incidence of muscle injury. The problem may be that many of the before mentioned studies used highly-trained college-aged athletes. The body’s of such individuals have adapted quite well to a demanding exercise load.

Muscle cramping might result from an electrolyte imbalance downstream of dehydration. Alternatively, muscle lesions might result from an athlete over-reaching their physical capacity. In other words, during creatine supplementation the amount of force we are able to generate may increase faster than our muscle’s (ligaments, tendons, etc) ability to adapt to the increased load; a weakest link phenomena. Again, drink plenty of fluids while taking creatine!

Renal Stress:

Sensible creatine use doesn’t appear to adversely influence kidney function in healthy individuals. There is some concern, however, that “creatine abuse” may place undue stress on the kidneys, particularly during the loading phase when large quantities of creatine are being ingested on a daily basis. During loading the kidneys must work harder to clear any unabsorbed creatine from the blood stream. Persons with pre-existing kidney disorders, or predisposed to renal dysfunction, such as diabetics, should omit the loading phase of supplementation, or abstain from creatine use altogether. These individuals, should they choose to supplement, should also be checked by their doctors on a regular basis.

Blood Pressure:

There was some concern that creatine-induced fluid retention could influence blood pressure. This was the topic of a recent scientific study demonstrating that acute creatine use does NOT alter blood pressure. Importantly, some blood pressure medications may negatively interact with creatine use. This is explained in more detail in our Creatine Guide.

Creatine Benefits:

Not all of creatine’s reputed side effects are detrimental. For example, recent research has shown that creatine supplementation may improve our serum cholesterol levels. In addition, muscle volumizing may serve as a stimulus to initiate the production of new muscle proteins. There are also indications that creatine may possess antioxidant properties on its own. Finally, and most importantly for overall health, creatine supplementation may reduce serum homocysteine levels by sparing the body’s methyl reserves. Reducing serum homocysteine levels, in turn, will greatly improve physical and mental health, potentially, a very important benefit of creatine supplementation with profound clinical implications. This little-known aspect of creatine supplementation is uniquely explained in our Creatine Guide.


Pure creatine monohydrate is not toxic. Certain impurities, however, may be potentially harmful. Creatine monohydrate is produced commercially by mixing sodium sarcosine and cyanamide in a heated water bath. Although seemingly straightforward certain chemical by-products may be formed, especially if inferior quality starting materials are used or sufficient care isn’t exercised during synthesis. These contaminants are particularly evident for cheaper brands of creatine. Moreover, some of the impurities present in poorer quality brands of creatine are potentially toxic and may give rise to adverse side effects.

The presence of contaminants is particularly worrisome during the loading phase when much greater amounts of creatine are consumed each day. A person loading with a poorer quality creatine product may actually be taking in grams of potentially toxic impurities each week.

Finally, some cheaper (or less scrupulous) creatine products have been shown to contain trace amounts of certain anabolic steroids. The presence of steroids in some cheaper creatine products may account for incidences of false-positives in some creatine users. Importantly, under the new Anabolic Steroid Control Act of 2005 (USA), ignorance is no excuse. If you test positive for any banned agent you may be barred from receiving federal financial aid as well as be declared ineligible for further athletic competition. This is no joking matter. In essence, cheaper brands of creatine literally dilute the amount of “real creatine” with contaminants making them pointless, potentially harmful, possibly illegal and a huge waste of money.

Given these caveats, it’s important that you purchase only quality creatine products. Full descriptions of creatine’s possible contaminants as well as the best producers of high quality creatine internationally are discussed in Creatine: A practical guide.

Click here for an official list of drugs banned by the NCAA.

Rumors & Unexplained Side Effects:

Side effects that cannot be explained from what is scientifically known about creatine are sometimes reported. Whether these side effects represent fact or fiction is still a matter of controversy. Some unexplained side effects may be merely rumor and arise from creatine being mistakenly associated with anabolic steroids. On the other hand, other incidences of unexplained side effects may be real and stem from contaminants or additives present in cheaper brands of creatine. This second set of unexplained side effects may have previously escaped detection owing to the fact that most scientific studies use only the highest-grade creatine products, WITHOUT unstudied additives that could confound the analysis of the data.

Unsubstantiated side effects reported include breast formation in men (gynecomastia), a reduction in penis size, hair loss (men), hair growth (women), acne and stunted growth in children. Unexplained incidences of aggression have also been sometimes linked to creatine use.

Examples of personal accounts of some unexplained side effects attributed to creatine use can be found here.

Unexplained Effects of Creatine?

Having raised these concerns about certain “unexplained dangers” of creatine supplementation (above), it is now important to stress that certain “unexplained BENEFITS” of creatine supplementation have also been recently uncovered.

Fortunately, the majority of the negative attributes sometimes linked to creatine supplementation can be easily circumvented by purchasing only quality creatine products; that is, most negative side effects are not the result of the creatine per se. Equally fortunate, the positive benefits of creatine supplementation can be fortified with a simple nutritional intervention.

It is my personal belief that many of these “mysterious benefits” now being attributed to creatine supplementation, but lacking full explanations, have to do with creatine’s ability to increase the body’s capacity to methylate important cellular targets, including our genes and essential anabolic modulators. Exactly how creatine supplementation spars the body’s methyl reserves is discussed in a recent issue of the Creatine Newsletter.

Misconceptions: Oh, Fat is Fat and Muscle is Muscle, “and never the twain shall meet”…

Muscle will not convert to fat after stopping creatine supplementation. It simply can’t. Muscle and fat are two completely different tissue types.

Our muscles initally grow in response to creatine use as a result of increased hydration (aka, muscle volumizing) and later on because of an increase in muscle protein content (aka, protein synthesis). After stopping creatine supplementation any gains in muscle size that were attributed to muscle volumizing will be lost . This is unavoidable. Remember, however, that this is only muscle water that is being lost, not muscle proteins. On the other hand, any gains you made as a result of increased muscle protein content will be more enduring.

The only way you can create body fat is to consume more calories than you burn with physical activity. Therefore, if your activity level decreases significantly after stopping creatine supplementation, while your caloric intake remains the same (or increases), you will gain fat.

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