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Instalab ResearchThe modern creatine boom began in the 1990s after Olympic athletes and professional football players began crediting it for their strength gains. News stories followed, calling creatine a “legal steroid.” The comparison was enough to alarm parents and health authorities, and soon, rumors spread:
Part of the confusion came from timing. Early users were often taking large “loading” doses of up to 25 grams a day, well above the maintenance levels we now know are effective. Some also failed to drink enough water, leading to temporary bloating or stomach upset. These experiences were anecdotal, but they made headlines.
At the same time, laboratory studies began noticing a small rise in serum creatinine among creatine users. Creatinine is a blood marker used by doctors to assess kidney function and this increase was interpreted as evidence of kidney stress. By the early 2000s, fears about kidney damage had become the dominant myth surrounding creatine use.
To understand creatine’s safety profile, it helps to understand how it works.
Creatine is a naturally occurring compound synthesized by the body from the amino acids arginine, glycine, and methionine. About 95% of it is stored in skeletal muscle, where it helps regenerate adenosine triphosphate (ATP), the molecule that fuels muscle contractions.
During high-intensity exercise, ATP is rapidly depleted. Creatine donates a phosphate group to help rebuild ATP more quickly, allowing muscles to work harder for longer. This is why creatine supplementation reliably increases strength and power output.
Concerns about creatine and kidney damage trace back to a few isolated case reports from the 1990s. In those early reports, people who already had kidney disease experienced worsening function after taking creatine. And because creatine slightly raises serum creatinine, a blood marker that physicians use to assess kidney health, many assumed the supplement might be responsible.
In reality, the explanation is much simpler. The body naturally maintains a steady balance of creatine and creatinine through continuous turnover. When someone supplements creatine, a small portion is converted into creatinine and excreted in urine. However, this rise in serum creatinine is completely harmless; it reflects a normal metabolic process rather than kidney damage.
Modern studies that use more precise measures of kidney health, such as glomerular filtration rate (GFR), have consistently found no evidence of damage. Even controlled trials involving up to 30 grams of creatine per day for several months, and in some cases years, showed no changes in kidney filtration rate, urinary protein excretion, or blood urea nitrogen levels.
As research accumulated, those early concerns began to fade.
Even among higher-risk groups, such as people with type 2 diabetes or those combining creatine with intensive exercise, kidney function remained stable. While anyone with diagnosed kidney disease should consult a physician before using creatine, the scientific evidence is clear. For healthy individuals, creatine does not harm the kidneys.
Another concern has been liver toxicity. Because creatine metabolism involves nitrogen and methylation reactions, it seems logical that the liver might bear an extra “toxic load.” In practice, studies measuring liver enzymes such as ALT, AST, and alkaline phosphatase show no abnormalities in creatine users.
In one large safety analysis published in 2025, researchers reviewed hundreds of clinical trials and found no difference in liver markers between creatine and placebo groups. These findings have been echoed in independent clinical and military studies over the last two decades. Long-term supplementation has not been linked to inflammation or structural liver changes.
The liver myth likely persisted because of guilt by association. Some anabolic steroids, which were sometimes marketed alongside creatine in the 1990s, truly can harm the liver. It is possible that creatine was unfairly lumped into the same category.
Athletes in the early 2000s often avoided creatine before competitions because of fears about dehydration and cramping. The theory was that creatine draws water into muscle cells, reducing fluid availability elsewhere in the body.
Physiologically, creatine does increase intracellular water. Each gram of creatine pulls roughly 15–20 grams of water into the muscle. But rather than dehydrating the body, this effect improves cellular hydration and thermoregulation. Muscles actually become better equipped to handle heat stress.
Dozens of clinical trials and field studies have tested this directly. Athletes who took creatine during summer training camps or military drills in high heat showed no increase in cramping or dehydration compared with placebo groups. Some even demonstrated enhanced heat tolerance and lower core temperatures during prolonged exercise.
Today, the dehydration theory is still one of the most persistent myths in sports nutrition, born from a misunderstanding of basic fluid dynamics.
Another common complaint is that creatine causes bloating. While it is true that creatine can increase total body water by about 1 to 2 kilograms during the first week of use, the majority of that water is stored inside muscle cells, not under the skin. This intracellular water actually supports muscle function and may even protect against injury.
For most, the mild weight gain is simply a sign of improved muscle hydration and energy storage, not aesthetic puffiness. Some people are more sensitive to this effect, especially if they use high loading doses. By reducing the loading phase to smaller daily doses (around 3 to 5 grams), these users can avoid even transient bloating altogether.
A small minority of users experience mild gastrointestinal distress such as stomach cramping or loose stools. This typically happens when creatine is consumed in large doses all at once or without sufficient water.
Studies that divided the daily dose into smaller servings found that nearly all digestive symptoms disappeared. Because creatine is osmotically active, it can draw water into the intestines if taken in excess, leading to temporary discomfort.
Proper dosing, usually 3 to 5 grams per day mixed with plenty of fluid, is sufficient for maintaining muscle saturation while minimizing any digestive issues.
The most comprehensive analyses now agree: creatine monohydrate, when taken at recommended doses, is one of the safest and most effective supplements available. Researchers from the International Society of Sports Nutrition have gone as far as to issue an official position stating that both short-term and long-term creatine use, at doses of up to 30 grams per day for as long as five years, is safe and well tolerated in healthy individuals of all ages.
Still, the conversation about safety is never absolute.
Those with pre-existing kidney disease, hypertension, or diabetes should consult a healthcare professional before beginning supplementation, particularly if they use medications that influence kidney function. People who experience digestive sensitivity may also wish to start with smaller doses to gauge tolerance.
In all cases, quality matters. Choosing a reputable brand that provides third-party testing ensures purity and consistency, reducing the risk of contamination or mislabeled ingredients. When used responsibly and sourced from a reliable manufacturer, it stands as one of the safest and most effective options for improving energy, focus, and long-term health.
