I too am allergic to iodine which is used for CT Scans. There is another dye they can use but you have to tell them of your allergy. I have had to tell each and every person involved with the CT Scan of my allergy right up to the person who gives you the IV. Some aren't so quick to believe you so be ademant about it. There IS something else available and they should have given you benadryl before they gave you the dye anyway.