Safety

Is creatine safe?

By GyroscopeUpdated November 14, 20268 sources

For healthy adults at 3 to 5 g a day, yes. The real effects are a few pounds of water in the first weeks and a higher creatinine number on blood tests, and big single doses can upset your stomach. If you have kidney disease or you’re pregnant or breastfeeding, ask your doctor first.

Creatine became a popular supplement in the early 1990s, and since then people have blamed it for kidney damage, hair loss, cramps and dehydration. Some still think it’s a steroid. It’s sold in the same aisle as products with real problems, so the suspicion sticks.

The effects that are real

• Water. A loading week typically adds 2 to 7 lb (1 to 3 kg), mostly water that goes into muscle with the creatine. 3 to 5 g a day adds less, more slowly. The International Society of Sports Nutrition calls weight gain the only side effect trials report consistently.
• A higher creatinine number. Creatine breaks down into creatinine, so fuller muscles put more of it in your blood. Across 26 trials it went up about 0.14 mg/dL. That can make the kidney score on a blood test look lower while measured kidney filtering stays the same. Here’s how that works.
• Your stomach, at big doses. In a trial of 59 soccer players, one 10 g dose a day gave 56% of them diarrhea, against 29% on two 5 g doses and 35% on placebo.

The fears that don’t hold up

• Kidney damage. In those 26 trials, filtering measured directly didn’t drop.
• Hair loss. A 2025 trial measured hair in 45 men taking 5 g a day or placebo for 12 weeks and found no difference. See hair loss.
• Cramps and dehydration. Over a season of college football in the heat, players on creatine had fewer cramps than players not taking it. See cramps.

How much testing there is

Creatine has been tested a lot. In 2025 Kreider’s lab at Texas A&M counted 685 human trials of it. Side effects were reported in 13.7% of the creatine groups and 13.2% of the placebo groups. Those are shares of trials that mentioned any side effect, and they don’t count people. It’s also a conference abstract from a lab that studies creatine, so the exact numbers are rough, but the two groups look alike.

The longest data come from patients. The International Society of Sports Nutrition reports that people with neurological and muscle diseases took up to 30 g a day for as long as five years and tolerated it well. American college football players took 5 to 10 g a day for 21 months with no meaningful differences from non-users in kidney, liver, blood or urine tests.

A real risk is what’s in the tub. The American Academy of Pediatrics lists high rates of contamination among its concerns about legal performance supplements. A third-party test mark is how you lower that risk.

Where the expert groups stand

• International Society of Sports Nutrition, 2017. Short and long-term use is safe and well tolerated in healthy people. People with kidney disease are advised to check with their doctor first, as a precaution.
• Two 2026 reviews of the trials, 26 and 20 trials. Creatinine rises 0.13 to 0.14 mg/dL on creatine, with no drop in urea or in filtering measured directly.
• National Kidney Foundation, updated 2023. For people who have lots of muscle, a cystatin C test may give a more accurate kidney result than creatinine.
• American Academy of Pediatrics, 2005 and 2016. Against performance-enhancing substances, supplements included, for children and teens.

Checked against these sources on November 14, 2026.