Have you ever had an allergic reaction to radiocontrast dye, also referred to as iodinated contrast?
These reactions typically occur when contrast agents, commonly iodine-based, are administered to enhance the visibility of specific tissues or organs during procedures like computed tomography (CT) scans or angiography. Adverse reactions are generally categorized as either immediate or delayed. Immediate reactions, occurring within minutes to an hour of contrast administration, range from mild symptoms such as flushing, itching, or nausea to more severe symptoms like respiratory distress and anaphylaxis. Delayed reactions, although less common, can present hours to days post-procedure and may involve skin rashes or kidney-related complications.
If you have ever had a reaction to contrast dye, it is crucial to differentiate between true allergic reactions and non-allergic responses. True allergies involve an immune system response to the contrast agent, whereas non-allergic reactions are often related to the physicochemical properties of the contrast medium. While the overall incidence of true allergic reactions is low, individuals with a history of previous reactions, asthma, or certain medical conditions may be at a higher risk.
For many of those who have had reactions to contrast dye, special pre-treatment protocols with antihistamines and corticosteroids may be considered to help prevent future reactions. The pretreatment protocol can reduce the risk of future reactions down to 10%! There are also other precautions that can be discussed to reduce the chance of reactions.
It is a common myth that shellfish allergy is connected to contrast dye allergy. This is because they both use iodine. Thankfully, iodine does not cause allergic reactions and having a shellfish allergy does not place you at increased risk of contrast reaction. If you have more questions about this, you can discuss it with your allergist!