Contrast Medium - Adverse Effects

Adverse Effects

While modern contrast media are generally safe to use, medical conditions can be caused by the administration of various contrast media. Reactions can range from minor to severe, sometimes resulting in death with death being about 0.9 per 100,000 cases. To better understand the reactions and to efficiently manage patients at risk, it is useful to classify them. Risk factors for developing severe reactions include strong allergies, bronchial asthma, cardiac disease and beta-blocker use.

A common misconception that even exists among healthcare professionals is that an allergy to contrast media is related to an allergy to seafood (usually shellfish) because both share iodine in common, implicating iodine as a source. Numerous studies have shown that although iodine is common in contrast media, iodine is not the cause of allergic reactions to contrast media and instead the more likely culprit are the inert ingredients and the patient's past history of having other strong allergic reactions. One important distinction is that allergic effects are by definition immunoglobulin E related histamine storms and studies have shown that contrast media cause no such reaction in vivo thereby refuting the possibility that contrast media or the iodine in it is likely to be an allergen. Although it may seem contradictory, the few rare cases of contrast medium mediated IgE are exceedingly rare compared to all adverse reactions and when they happen, are often because the patient already has multiple risk factors that suggest the patient has other allergy related problems.

Historically, contrast media was sometimes highly dangerous but these dangers were not well-understood during the development of the early types of contrast media, such as Thorotrast.