CT scans are amazing tools. They can reveal hidden damage, guide surgeons in the middle of life-saving procedures, and give doctors answers they simply can’t get any other way. But like most powerful tools, they come with trade-offs. And once you add in the dyes used for “contrast,” the risks climb a little higher.

That’s not to say you should fear every CT. But as more and more people get them, scientists are sounding the alarm: understand the risks, especially when it comes to cancer.

What the Research Shows

A 2022 review that pulled together 25 different studies came to a sobering conclusion: the more radiation someone got from multiple CT scans, the higher their cancer risk. Folks who had fewer scans, or low-dose versions, didn’t face the same odds.

Certain tissues are far more vulnerable. Breasts, bone marrow, colon, lungs, stomach—these are radiosensitive. Arms and legs? Not nearly as much.

A recent study out of UCSF even suggested CT scans could be linked to up to 5% of new cancers every year in the U.S. Why? The sheer number of scans being done, and the fact that many use more radiation than necessary.

Kids face the biggest gamble. Their cells divide faster, their bodies are still developing, and they’ve got a lot more years ahead for any damage to show itself. Multiple CTs in childhood are strongly tied to certain cancers later on.

Who’s Most at Risk

• People who’ve had scan after scan over the years.
• Children and pregnant women.
• Organs that are naturally more sensitive, like the breast, colon, lungs, stomach, and bone marrow.

Two Questions to Ask Before You Agree to a CT Scan

1. Is it really necessary? Sometimes it is. Sometimes it isn’t. And you have every right to ask. Too often, people just go along with whatever’s ordered, not realizing there may be safer choices. MRIs, for instance, use magnets—no radiation—and they’re excellent for the brain, spine, and soft tissues. Ultrasounds? Same deal: no radiation, no dye. They’re the go-to for things like heart checks, blood flow, or the abdomen.
And here’s the kicker: even when a CT is needed, there are low-dose options. They give your doctor the answers without flooding you with unnecessary radiation. So speak up. Ask, “Is there a safer scan that could tell us the same thing?”

2. Do I really need the dye? Contrast dye sharpens the picture. No question. But it isn’t always required. Most people process it and move on. Some, though, get side effects—itching, queasiness, maybe a rash. Rarely, the reaction is more serious. And if your kidneys aren’t strong, that dye can pile on extra strain.

As a cancer survivor, I can tell you this: I learned to question every single step. You don’t have to be confrontational, just clear. Ask, “Can we do this without the dye? Or maybe a lower-dose version?” It’s your body. You deserve to know the risks and weigh the benefits.

>>Note: If I had a CT scan, I would take Vitamin C for sure. I’d start with 20g per day for at least four days. Vitamin C is so important that I devoted an entire chapter to it in my book, “I Used to Have Cancer.” Learn more in my article, “How Vitamin C Saved My Life.”

The Bottom Line

CT scans save lives. They also carry risks. The more you know about those risks—and the alternatives—the better your conversations with your doctor will be. Don’t be afraid to speak up. In the end, being your own advocate is one of the best tools you’ve got.

Resources:

Cao CF, Ma KL, Shan H, Liu TF, Zhao SQ, Wan Y, Jun-Zhang, Wang HQ. CT Scans and Cancer Risks: A Systematic Review and Dose-response Meta-analysis. BMC Cancer. 2022 Nov 30;22(1):1238. doi: 10.1186/s12885-022-10310-2. PMID: 36451138; PMCID: PMC9710150.

Pearce, Mark S., Jane A. Salotti, et al. “Radiation Exposure from CT Scans in Childhood and Subsequent Risk of Leukaemia and Brain Tumours: A Retrospective Cohort Study.” The Lancet 380, no. 9840 (2012): 499-505. https://doi.org/10.1016/S0140-6736(12)60815-0

Fernandez, Elizabeth. “Popular CT Scans Could Account for 5% of All Cancer Cases a Year.” UCSF News Center, April 14, 2025. https://www.ucsf.edu/news/2025/04/429791/popular-ct-scans-could-account-5-all-cancer-cases-year.

Schultz CH, Fairley R, Murphy LS, Doss M. The Risk of Cancer from CT Scans and Other Sources of Low-Dose Radiation: A Critical Appraisal of Methodologic Quality. Prehosp Disaster Med. 2020 Feb;35(1):3-16. doi: 10.1017/S1049023X1900520X. PMID: 32009606.