Does creatine affect cancer risk? What the research does and doesn't show

The evidence doesn't support a claim that creatine, at any dose, causes cancer, prevents cancer, or belongs alongside cancer treatment. What exists is an active, unsettled area of laboratory and mouse research, described by the researchers themselves as having "two sides," and no human trial has measured cancer risk or outcomes from taking a creatine supplement.

What the evidence doesn't support

It doesn't support creatine as something that raises or lowers a person's cancer risk — nobody has run that trial in people. It doesn't support using creatine as part of cancer treatment, and one of the reviews below explicitly urges caution around creatine supplementation specifically for people being treated for cancer, based on the mouse research described here. And it doesn't support a single, settled story in either direction: the mouse and cell research below points different ways depending on the specific model being studied.

What the trials found

A review titled "The two sides of creatine in cancer" lays out how the picture has changed over time. Older studies, using mice with tumors implanted under the skin, found creatine and a related compound suppressed tumor growth — the original basis for thinking of creatine as cancer-suppressive. More recent studies used a more realistic setup: tumors grown in their natural organ location inside the mouse, rather than under the skin. In that setup, creatine was associated with more invasion and spread of pancreatic, colorectal and breast cancer. The review's own conclusion is that creatine's role in cancer progression is genuinely complex, and it specifically cautions against creatine supplementation for people currently receiving cancer care — a caution aimed at that specific group, not a statement about the general population.

A 2026 study dug into a specific mechanism for that spread: creatine supplementation raised activity of an enzyme in platelet-producing cells, which in turn made platelets more prone to promoting metastasis, across several mouse cancer models. Blocking that pathway, genetically or with a drug, stopped the effect in mice. The same study gave creatine to a small group of healthy human volunteers and found their circulating platelets became more reactive afterward — the authors argue this could plausibly raise metastasis risk in someone who already has cancer. It's worth being precise about what that human data does and doesn't show: it measured platelet activity in healthy people, not cancer outcomes, metastasis, or cancer risk directly, in anyone.

A separate mouse study on obesity-driven breast cancer found the body's own internal creatine-production pathway, active in fat tissue near a tumor, helped fuel tumor growth in obese mice; blocking that internal pathway slowed it. This describes creatine the body makes on its own inside a tumor's environment, in a specific mouse model of obesity-linked cancer — it isn't a study of taking a creatine supplement.

Pointing the other way, a mouse study of cancer cachexia — the severe muscle wasting that can accompany advanced cancer — found creatine supplementation in tumor-bearing mice was associated with less body-weight and muscle loss and better grip strength than in untreated tumor-bearing mice. Cachexia patients' blood samples in the same study showed lower creatine levels than expected. This is the "other side" the review above refers to: in a model of cancer-related muscle wasting, creatine supplementation looked protective for muscle, rather than promoting the disease itself.

A broader review of creatine metabolism describes cancer cell biology as one of several areas — alongside fat-tissue energy use and immune-cell function — where creatine's role is still being actively worked out in the laboratory, not a finished picture.

Questions people ask

Does creatine cause cancer?

No human study has tested that question. The mouse and cell research above is mixed and depends heavily on the specific cancer model used — some findings point toward more spread of certain cancers, others point toward creatine helping preserve muscle in cancer-related wasting. None of it establishes that creatine causes cancer in a person.

Is creatine safe if I have cancer or I'm in treatment?

This is exactly the group the "two sides" review specifically urges caution about, based on the mouse research showing certain cancers spread more in the presence of creatine. If you have a cancer diagnosis or are in treatment, talk to your oncologist before taking creatine — this is a conversation for your care team, not something this page can settle from general research.

Can creatine cause a tumor?

No study we found reports that in people. Mouse studies have found mixed results depending on the model: some showing creatine associated with tumor growth, others showing the opposite, and none of it involves a human trial measuring tumor development from taking a supplement.

When to talk to a doctor

If you have a cancer diagnosis, are undergoing treatment, or are in remission and considering any new supplement, talk to your oncologist first — the mouse research above specifically raises questions for that group that this page can't answer for you individually. Creatine is not a treatment for cancer, and nothing here is a reason to start or stop anything related to cancer care without your doctor's input.

Related reading: creatine and inflammation: what the research does and doesn't show, creatine benefits: what the research does and doesn't show, and creatine side effects.