3 July 2026

Is Creatine Safe? What Decades of Research Say

Creatine is one of the most studied supplements in the world, yet it still carries a reputation that makes people pause. You may have heard it is hard on your kidneys, or that it is only for bodybuilders, or that "natural" somehow means safer than a scoop of white powder. If you are a woman who has never touched a sports supplement before, the questions can feel even louder. Wanting a straight answer before you start anything daily is completely reasonable.

Everything below describes independent research about creatine and citicoline in general. It is educational, not medical advice, and not a claim about any product. If you have a health condition or take medication, your GP or pharmacist is the right person to ask about your own situation.

Why creatine has a safety reputation at all

Much of the worry traces back to a single misunderstanding about kidneys. Creatine is broken down into a waste product called creatinine, which doctors measure to check kidney function. Take extra creatine and your creatinine reading can nudge upward. That is a change in a lab number, not evidence of harm, but it was enough to start a rumour that has quietly outlived the science.

What the long-term studies found

Researchers have actually gone looking for that harm. Poortmans and Francaux tracked healthy athletes taking creatine for anywhere from ten months to five years and reported no impairment of kidney function (Medicine & Science in Sports & Exercise, 1999). In a separate review they weighed the alarming media claims against the actual data and titled the paper, pointedly, "fact or fiction" (Sports Medicine, 2000).

Longer and larger studies tell a similar story. Kreider and colleagues followed college athletes for up to 21 months, screening a panel of nearly 70 blood and urine markers, and found no meaningful adverse effect on health markers compared with athletes who did not supplement (Molecular and Cellular Biochemistry, 2003).

The position of the sports nutrition field

In 2017 the International Society of Sports Nutrition published a formal position stand reviewing the evidence on creatine safety and effectiveness (Kreider et al., Journal of the International Society of Sports Nutrition, 2017). Its summary was refreshingly blunt: creatine monohydrate is among the most effective and best-tolerated supplements studied, with no consistent evidence that recommended doses harm healthy people.

This is also the one benefit European regulators have authorised as a statement of fact: creatine increases physical performance in successive bursts of short-term, high-intensity exercise. That is the claim, no more and no less. Everything else you read about creatine sits in the realm of ongoing research.

The everyday side effects people actually notice

Being well tolerated is not the same as being invisible. The most common thing people report early on is a little water weight, as muscle cells hold on to slightly more fluid. It is cosmetic, and it settles. We wrote a whole piece on why creatine can cause weight gain and what it really means for the number on the scale. Some people also notice mild stomach discomfort if they take a large dose in one go, which is one reason a steady daily amount tends to sit more comfortably than old-fashioned heavy loading. Our guide on how to take creatine covers that in plain terms.

Dose matters here more than almost anything. A typical daily serving in the research is around five grams, which is what perco delivers in a single unflavoured, caffeine-free sachet. There is little reason for a healthy adult to go chasing bigger numbers.

Where citicoline fits

perco pairs creatine with citicoline, a clean source of the everyday nutrient choline, so it is fair to ask about that half too. Citicoline has been used and studied for many years. A 2022 review by Secades and Gareri reported that it is generally well tolerated, with side effects that are infrequent and mild when they occur (Revista de Neurología, 2022). As with creatine, that is a research observation about the ingredient, not a promise about how any product will affect you. If you want the basics first, our explainer on what citicoline is walks through it.

The honest summary

No supplement is right for everyone, and "well studied" is not the same as "risk free for you personally." But the specific fear that creatine quietly damages healthy kidneys has been tested many times over several decades, and it has not held up. For most healthy adults, the research points to a reassuringly boring safety record. Boring, in this case, is exactly what you want from something you take every morning.

Sources: Poortmans & Francaux, Medicine & Science in Sports & Exercise (1999); Poortmans & Francaux, Sports Medicine (2000); Kreider et al., Molecular and Cellular Biochemistry (2003); Kreider et al., Journal of the International Society of Sports Nutrition (2017); Secades & Gareri, Revista de Neurología (2022). Educational summary of independent third-party research. Not medical advice; not a claim about any product.