Why do I need contrast dye for a CT scan?

Contrast dye is used during some CT scans to make the pictures clearer, which helps your care team see certain areas of your body more easily. It can be given in different ways depending on what part of your body is being scanned: by mouth, injected into a vein, or given by enema. Common contrast materials include iodine and barium.

Not everyone needs contrast — it depends on what your doctor is looking for. If you do need it, reactions are rare. Some people have a mild reaction, such as itching or hives. More serious reactions, such as shortness of breath or swelling, are rarer still, but it is important to tell the technologist right away if you notice any of these signs during or after your scan so they can help.

If you have had a reaction to contrast dye before, or you have any allergies or kidney concerns, let your care team know ahead of time so they can plan accordingly.