Creatine Side Effects & Safety

How safe is creatine?

The ISSN position stand reports that short- and long-term use, up to 30 g a day for 5 years, was safe and well tolerated in healthy people and in several patient groups, from infants to the elderly (ISSN position stand, 2017). The NIH Office of Dietary Supplements calls creatine safe for short-term use by healthy adults and notes evidence that use for several years is safe (NIH Office of Dietary Supplements).

Creatine and your kidneys

This is the most common worry. A 2019 systematic review and meta-analysis concluded that creatine supplements did not cause kidney damage at the amounts and durations studied (de Souza e Silva et al., 2019). The ISSN expert team traced the fear back partly to a 1998 case report in a man who already had kidney disease and took an immunosuppressant drug, and to confusion between creatine and creatinine (Antonio et al., 2021).

Creatinine is the waste product of creatine, and doctors use blood creatinine to estimate kidney function. Creatine supplements can raise it a little without meaning your kidneys are worse (Antonio et al., 2021). So tell your doctor you take creatine before a blood test. And if you already have kidney disease, or take medicines that affect the kidneys, do not take creatine without your doctor’s approval; the case reports of problems involved pre-existing kidney disease, medications, other supplements or extreme doses (Antonio et al., 2021).

Does creatine cause hair loss?

The idea comes from a 2009 study in 20 college rugby players: after a week of 25 g a day, the hormone DHT rose 56% and stayed 40% above baseline during maintenance (van der Merwe et al., 2009). The study did not look at hair. In 2025, a 12-week randomized trial of 5 g a day in 38 men measured hormones and hair directly and found no differences in DHT or hair density, follicle counts or thickness between creatine and placebo (Lak et al., 2025). Current evidence does not support the hair-loss claim, but it is based on few studies.

Water weight, bloating and stomach upset

Creatine often leads to some weight gain, mostly water, and the NIH notes 1–2 kg in a month during strength training (NIH Office of Dietary Supplements). It is most noticeable with a loading phase. Reported but less common effects include nausea, diarrhea, muscle cramps and stiffness; the NIH says adequate hydration might minimize these (NIH Office of Dietary Supplements). Splitting large doses and taking creatine with food helps many people. More in creatine water intake.

Myths the research does not support

• “Creatine is a steroid.” No. It has a completely different chemical structure from anabolic steroids (Antonio et al., 2021).
• “Creatine makes you fat.” No. Studies across many groups found it does not increase fat mass (Antonio et al., 2021).
• “Creatine causes dehydration and cramps.” The evidence says no; creatine users even had fewer cramps in one football study (Antonio et al., 2021).

Who should talk to a doctor first

• Anyone with kidney or liver disease, or a history of kidney problems.
• People taking prescription medicines, especially ones that affect the kidneys, and people with diabetes or other chronic conditions.
• Anyone who is pregnant or breastfeeding; human studies are lacking (Smith-Ryan et al., 2021).
• Children and teens. Some studies in adolescents found no harm (Antonio et al., 2021), but the NIH notes pediatric and high-school associations advise against performance supplements for adolescents (NIH Office of Dietary Supplements).

Buying a safer product

Choose plain creatine monohydrate, the form whose safety is best documented; the safety and regulatory status of newer forms is less clear (Jäger et al., 2011). Dietary supplements are not approved by the FDA before sale, so a product with independent third-party testing gives extra peace of mind.

Ready? Calculate a sensible dose, or read how much creatine per day.