Fact Checked

What Are the Side Effects of CT Scans?

Susan Abe
Susan Abe

A computerized tomography scan (CT) — formally known as computerized axial tomography or (CAT) — is a type of radiographic imaging procedure that takes many pictures of a given area for optimal evaluation of body structures. The many images generated from a CT scan can be manipulated on the computer to create different axial views of the body. In other words, the body's interior can be viewed along different axes, or planes, for comparison. Side effects mayb be long-term or short-term, depending upon when they might arise. Long-term side effects of CT scans are mostly conjecture, while short-term side effects may include anxiety or untoward reactions to the contrast dyes sometimes used for optimal visualization.

All documented side effects of CT scans are considered short term. The vast majority are secondary to the administration of fluorescent, or contrast, dyes used to increase visibility of certain details in the CT image. Contrast dyes — usually made of iodine — can cause allergic reactions in some patients, particularly individuals with a preexisting allergy to seafood. Fluorescent dye allergies are apparent more quickly when the contrast material is administered intravenously (IV) than by mouth, as intravenous administration of the medication distributes the dye more quickly throughout the body. Allergic reactions to contrast dyes can include the development of hives, rashes, itching or wheezing.

CT scans may cause anxiety.
CT scans may cause anxiety.

Other reactions to the procedure might be broadly considered side effects of CT scans. A common reaction to IV administration of an iodine-based contrast dye is an abrupt systemic flushing that is also described as a feeling of heat spreading throughout the body. This is a known reaction to the dye and is not reported to cause permanent difficulties. Many patients — already anxious about possible health problems and the unfamiliar procedure — report claustrophobia while within the cylindrical CT scanner. These patients are often sedated with anti-anxiety medication prior to the procedure and may thus experience drowsiness and sedation as a side effect of CT scans.

The iodine-based dye sometimes used for CT scans may produce an allergic reaction.
The iodine-based dye sometimes used for CT scans may produce an allergic reaction.

A CT scan uses a slightly higher amount of radiation than a usual x-ray to obtain its multiple images and exposure to radiation has been identified as increasing an individual's chance of developing cancer. Thus, potential long-term side effects of CT scans may include greater chances of developing a malignancy. These risks are reportedly less dangerous than failing to diagnose or monitor a current medical condition in an adult.

You might also Like

Discussion Comments


I had a CT scan with no during the afternoon yesterday and by the early evening I felt like I had mild flu symptoms and a slight fever (100.7) This morning I feel fine, with no fever. Is this a normal side effect?


A head and neck CT scan for a superficial cheek injury was the worst thing that ever happened to me by far. For the past 10 weeks I've been in tremendous distress. I've had headaches, speech difficulties, sleep problems, skin problems, a sensation in my spine between my shoulder blades, balance issues, ringing in my ears, etc., etc., are all a direct result of a CT scan I was coerced into having.

Something went wrong because I felt a sensation in my head from the scan itself. One is not supposed to feel a CT scan, but nobody explained anything to me about radiation exposure or anything else. I'm still trying to recover. Never take a CT scan if possible.


I feel terrible for about a day after a CT scan. I get the typical feeling of warmth and bad taste in my mouth from the contrast dyes. But when I get home, I feel exhausted and sick, like I have the flu.


@MikeMason-- CT scans are not that bad. I've had two of them and it was much easier than I expected.

It's true that iodine can be dangerous for people who are allergic to it. But you won't be given a CT scan without checking if you're allergic to iodine first. You can even do an allergy test yourself at home by putting a few drops of iodine on your arm.

The only side effects I've had from CT scans are the heat sensation during the scan and then thirst afterward. I tend to drink a ton of water afterward, I guess to flush the dyes out of my system.

CT scans are very valuable diagnostic tools in my opinion. Some things can't be diagnosed without it. So the side effects are worth it.


My doctor wants me to get a CT scan to try and figure out the cause of my chronic migraines, but I refuse to get it. I know that we should avoid radiation as much as possible because of the risks of cancer.

The dyes used in CT scans also sound scary. Iodine is something found in some illegal drugs and has terrible side effects on the body. There is no way I'm letting anyone inject iodine into me.

Post your comments
Forgot password?
    • CT scans may cause anxiety.
      By: beerkoff
      CT scans may cause anxiety.
    • The iodine-based dye sometimes used for CT scans may produce an allergic reaction.
      By: ksena32
      The iodine-based dye sometimes used for CT scans may produce an allergic reaction.
    • CT scans can put a patient at a higher risk for cancer because of the increased exposure to radiation.
      By: Monkey Business
      CT scans can put a patient at a higher risk for cancer because of the increased exposure to radiation.