What is the dye injected before a CT scan?
James Holden
Updated on January 04, 2026
A special dye called contrast material is needed for some CT scans to help highlight the areas of your body being examined. The contrast material blocks X-rays and appears white on images, which can help emphasize blood vessels, intestines or other structures. Contrast material might be given to you: By mouth.
What are the side effects of contrast dye after a CT scan?
Side effects of iodine contrast can include: skin rash or hives. itching. headache.
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Possible side effects of an abdominal CT scan
- abdominal cramping.
- diarrhea.
- nausea or vomiting.
- constipation.