CAMRT Radiography Practice Exam

Which antihistamine is commonly administered after a mild allergic reaction to contrast?

1. Adrenalin

2. Benadryl

3. Xylocaine

4. Atropine

The correct answer is: Benadryl

The choice of Benadryl, also known as diphenhydramine, reflects its common use in managing mild allergic reactions, particularly those related to contrast media used in imaging studies. As an antihistamine, Benadryl works by blocking the action of histamine at the H1 receptor sites, which reduces symptoms such as itching, hives, and swelling that commonly accompany allergic reactions. In the context of a mild allergic reaction to contrast media, prompt administration of Benadryl can provide effective relief of the symptoms due to its sedative and anti-allergic properties, making it a standard practice in the medical setting. It is well-established in both its effectiveness and rapid onset of action, which further supports its frequent use after such reactions. Other options present in the question serve very different purposes. Adrenalin (epinephrine) is typically reserved for severe allergic reactions or anaphylaxis. Xylocaine (lidocaine) is a local anesthetic and doesn't address allergic symptoms. Atropine is an anticholinergic agent used to treat bradycardia and other conditions, unrelated to allergic responses. Thus, Benadryl stands out due to its targeted role in addressing symptoms of mild allergic reactions.