What happens if you get an allergic reaction to the contrast dye for ct scan?

It varies: Milder reactions include itching, hives, nasal stuffiness, watery eyes or mild mouth/tongue swelling. More serious reactions can occur and can even include anaphylaxis, the most serious of allergic reactions that can be life-threatening. People who have a known allergy are often pretreated with steroids to prevent reactions. All radiologists and techs are trained to treat contrast reactions.

See below: With iodinated based contrast you may get allergic reaction ranging from mild skin rash to severe rash, difficult breathing, severe drop in blood pressure and even cardiac arrest. Patients at risk are those with previous reaction, history of asthma or allergy. Please consult with your doctor.