Creatine is one of the best-researched supplements in sport, and at the same time the supplement surrounded by the most persistent stories. Kidney damage, hair loss, dehydration. Below is what is actually known, including the drawbacks that are real.
Weight gain in the first weeks
This is the most common and most visible side effect. In the first weeks many people gain one to two kilos.
That is fluid, not fat. Creatine is osmotically active and draws water into the muscle cell, increasing cell volume and making your muscles feel fuller. For most athletes that is no problem, but if you compete in a weight class or watch the scales, it is worth knowing that those first kilos say nothing about fat mass.
Stomach and bowel complaints
Some users report bloating, cramps or loose stools. This occurs more often at higher doses, for example during a loading phase.
There is a practical cause behind it that many people are unaware of: creatine only dissolves to a limited extent in water. At a typical dose of five grams in a glass you are well above the solubility limit. What you drink is therefore largely a suspension, with fine particles floating in the liquid. Undissolved particles reaching the gut draw water osmotically, and that contributes to the complaints.
What helps: shake it well and drink it straight away, so nothing is left at the bottom. Warm water improves the suspension. Spread your intake across the day or take it with a meal if you are sensitive to it.
Kidney damage: not supported
This is the best-known concern, and the reason many people never start with creatine.
The misunderstanding stems from a measurement issue. Creatine is converted in the body into creatinine, and creatinine in the blood is precisely the value doctors use to assess kidney function. Anyone taking creatine therefore has a higher creatinine reading without their kidneys working any less well. The marker rises, the function does not.
Long-term research in healthy people shows no kidney damage at normal doses.
Hair loss: one study, never replicated
The story began with a 2009 study of twenty rugby players, in which a rise in DHT was measured after three weeks of creatine use, a hormone involved in male pattern baldness.
Two things are almost always left out of that story. The measured values stayed within the normal range. And the study did not measure hair loss at all, only hormone levels. The link with baldness was added by others.
The study has never been replicated. More recent randomised research that did look specifically at hair loss found no effect.
When you should pay attention
If you have a kidney condition, take medication that burdens the kidneys, or are pregnant, talk to your doctor before starting. The same applies if you have blood work done: mention that you use creatine, otherwise your creatinine reading may cause unnecessary concern.
Sources
Van der Merwe J. et al. (2009). Three weeks of creatine monohydrate supplementation affects dihydrotestosterone to testosterone ratio in college-aged rugby players. Clinical Journal of Sport Medicine. Study of twenty rugby players in which a raised DHT to testosterone ratio was measured. Hair loss was not investigated; the finding has never been replicated.
Lak M. et al. (2025). Does creatine cause hair loss? A 12-week randomized controlled trial. Randomised research that looked specifically at hair loss.
About the author
Kemail Verhoeven is the founder of AP Nutrition. He has played sport for fifty years across basketball, martial arts, strength training and triathlon, and after a series of injuries and broken bones he immersed himself in injury prevention, recovery, nutrition and movement science. That knowledge is self-taught and forms the basis of the products AP Nutrition develops and manufactures in-house.
Related reading
Creatine loading phase: is it needed?
What is creatine and how does it work?