Creatine Side Effects: What Does the Science Say?

Creatine is the most studied supplement on the planet. Over 500 studies, and yet you still hear it is bad for your kidneys, makes you bloated, or causes hair loss. Time to separate facts from fiction.

Water retention: yes, but not what you think

Creatine pulls water into your muscle cells. In the first week you might gain 1-2 kg. That is intracellular water, not fat and not subcutaneous bloating. Your muscles look fuller, not your face. It stabilizes after the loading phase.

Kreijgsman et al. (2003) confirmed that creatine increases total body water, but specifically intracellular water. Extracellular water barely changes.

Kidneys: the most persistent myth

Creatine raises your blood creatinine levels. Creatinine is a breakdown product of creatine and is routinely measured in kidney function tests. More creatine in = higher creatinine. That does not mean your kidneys are working worse.

Poortmans and Francaux (2000) followed athletes who used creatine for years: zero measurable difference in kidney function. The International Society of Sports Nutrition (ISSN) confirmed in 2017 that creatine is safe for healthy individuals, even with long-term use.

Have an existing kidney condition? Talk to your doctor. For healthy people there is zero evidence of kidney damage.

Stomach issues

At high doses (10g+ at once) some people experience stomach cramps or diarrhea. The fix is simple: take 3-5g per day, not all at once. Creatine monohydrate with a meal is best tolerated.

Hair loss

This comes from a single 2009 study (van der Merwe et al.) in South African rugby players. They found an increase in DHT (dihydrotestosterone) after creatine supplementation. DHT is linked to male pattern baldness.

But: none of the participants actually lost hair. The study has never been replicated. Twelve other studies found no significant effect of creatine on testosterone or DHT. A single data point is not proof.

Liver damage

Zero evidence. No study has found liver damage from creatine use at normal doses. Even at 30g per day (a loading dose nobody takes long-term) there are no measurable effects on the liver.

Muscle cramps

An old myth. Lopez et al. (2009) specifically investigated this in NCAA athletes and found that creatine users actually had fewer cramps than the placebo group.

The reality

After 30 years of research, creatine monohydrate is one of the safest supplements you can take. The known side effects (water retention, stomach issues at high doses) are mild and easy to manage.

Curious which creatine scores best? Check the creatine comparison on WheyWijzer.