Creatine monohydrate is one of the most extensively studied supplements in sports nutrition, and the overall evidence strongly supports its safety for healthy adults. The International Olympic Committee lists it among the small group of supplements with “good to strong evidence” of benefit, and long-term studies spanning up to five years have found no adverse effects on organ health in people with normal kidney and liver function. That said, a few specific concerns come up repeatedly, and they’re worth unpacking.
What Creatine Does in Your Body
Creatine is a compound your body already makes, primarily in the liver and kidneys, and stores mostly in muscle tissue. When you supplement with it, you increase those stores, giving your muscles a larger reservoir of quick energy for high-intensity efforts like lifting, sprinting, or jumping. This is why it’s best known for improving strength and power output, and why it can help you train harder and gain lean mass over time.
Your brain also uses creatine for energy. A meta-analysis in Frontiers in Nutrition found that creatine supplementation significantly improved memory, attention, and information processing speed in adults. The mechanism is straightforward: more cellular energy reserves and less oxidative stress during demanding cognitive tasks.
The Kidney Concern, Explained
This is the single biggest worry people have, and it’s based on a misunderstanding of lab tests. When you take creatine, your body breaks down more of it into a waste product called creatinine, which shows up in blood work. Doctors use creatinine levels to estimate kidney function, so higher numbers can look alarming on paper. But the increase is a direct result of having more creatine in your muscles, not a sign of kidney damage.
Studies have consistently shown that in people with healthy kidneys, long-term creatine use does not change glomerular filtration rate (the actual measure of how well your kidneys filter blood) or cause structural damage to the kidney’s filtering units. Even chronic supplementation over five years has produced no adverse kidney effects in healthy athletes. If you’re getting blood work done while taking creatine, let your doctor know so they can interpret your creatinine levels in context.
The one caveat: people with pre-existing kidney conditions don’t have the same safety data behind them. If you have kidney disease or reduced kidney function, the research simply hasn’t established that creatine is safe for you.
Liver Function
A study published in the British Journal of Nutrition found that gym users who took dietary supplements (including creatine) had slightly higher levels of a liver enzyme called AST compared to non-users. But the researchers themselves noted these small elevations likely reflect normal physiological adaptations to exercise, not actual liver damage, and had no clinical relevance. A review covering research from 1997 to 2013 concluded that creatine supplementation does not induce organ damage at the amounts and durations studied.
Digestive Side Effects Are Real but Avoidable
Bloating, stomach cramps, and diarrhea are the most commonly reported side effects of creatine, and they almost always trace back to dose size. When you take more than about 10 grams in a single sitting, some of the creatine stays unabsorbed in your intestine, pulls water into the gut, and speeds up transit. The fix is simple: keep individual doses at 5 grams or less. If you’re doing a loading phase (20 to 25 grams per day for five to seven days), split it into four or five smaller doses throughout the day rather than taking it all at once.
Contaminants or additives in lower-quality creatine products can also cause stomach issues in sensitive individuals. Sticking with a well-tested creatine monohydrate from a reputable brand reduces this risk. Combining creatine with caffeine may also worsen gut discomfort for some people, since caffeine independently increases intestinal motility.
Creatine Does Not Cause Dehydration or Cramping
This is one of the most persistent myths in sports nutrition. Creatine does pull water into muscle cells, which led to early speculation that it might dehydrate you or cause cramps. Multiple studies have directly tested this and found no increased risk. In fact, the evidence now points in the opposite direction: creatine may actually help maintain blood volume during dehydration and improve your body’s ability to regulate temperature during exercise in hot or humid conditions. It has been shown to reduce exercising heart rate and sweat rate in the heat. There is little evidence that supplementing with creatine in any environment presents additional risk for heat illness.
Does Creatine Cause Hair Loss?
This concern traces back to a single 2009 study of college rugby players that found a 56% increase in dihydrotestosterone (DHT) after seven days of creatine loading. DHT is a hormone derived from testosterone that can shrink hair follicles and contribute to male pattern baldness. The problem: no study since has been able to replicate that finding. Twelve additional studies have examined creatine’s effects on testosterone and related hormones, and none found significant increases. There is no conclusive evidence that creatine raises testosterone or causes hair loss.
Safety in Teenagers
The American Academy of Pediatrics does not recommend creatine for anyone under 18. This isn’t because studies have found it to be harmful in adolescents. It’s because there simply isn’t enough data on young, still-developing bodies to confirm it’s safe. Despite this recommendation, surveys have found creatine use among middle and high school athletes at all grade levels. Until more research fills this gap, the conservative guidance from pediatric organizations remains: hold off until adulthood.
How Much to Take
The standard maintenance dose is 3 to 5 grams per day. That’s enough to keep your muscle creatine stores elevated once they’ve reached saturation, which takes about three to four weeks at that dose. If you want faster results, a loading phase of 20 to 25 grams per day for five to seven days will saturate your stores in about a week, after which you drop to the 3 to 5 gram maintenance range. Loading isn’t necessary, just faster. Both approaches end up at the same place.
Creatine monohydrate is the form with the most research behind it and is typically the least expensive. Other forms (hydrochloride, buffered, ethyl ester) exist but haven’t demonstrated meaningful advantages in head-to-head comparisons.