Emergency medicine updates: Contrast media hypersensitivity

Contrast media hypersensitivity reaction is a rare but clinically significant condition that can meaningfully affect emergency department (ED) patient care. Therefore, it is important for emergency medicine clinicians to be aware of the current evidence regarding the diagnosis, prevention, and management of this condition.

This paper evaluates key evidence-based updates concerning contrast media hypersensitivity reactions for the emergency clinician.

Adverse reactions to contrast media are divided into common physiologic reactions and less common hypersensitivity reactions. Hypersensitivity reactions can be immediate or delayed, ranging from mild urticaria to anaphylaxis. The greatest risk factor for hypersensitivity reaction to contrast media is a prior hypersensitivity reaction to contrast media. It is crucial to discern and document the specific culprit agent, severity, type, and timing of previous and current reactions. Physiologic reactions can be treated with supportive care and usually self-resolve. Acute evaluation and treatment of moderate-to-severe hypersensitivity reactions mirrors standard anaphylaxis care, with intramuscular epinephrine as the first-line drug for severe reactions, and allergist referral should be considered. Patients with a prior physiologic reaction do not require premedication or contrast switching. For prevention of breakthrough hypersensitivity reactions, switching to a chemically different contrast agent is more effective than corticosteroid premedication. Routine corticosteroid premedication is no longer recommended, as literature has not demonstrated corticosteroid pretreatment reduces hypersensitivity reactions. Second-generation antihistamines may be of benefit for patients with a history of mild-moderate reactions. Severe or anaphylactic reactions warrant strong consideration of alternative imaging. Collaboration with key stakeholders, including radiology and pharmacy, is important to improve workflows, protocols, and patient care.

An understanding of literature updates can improve the ED care of patients with contrast media hypersensitivity reactions.