Which medication is included in the moderate/severe allergic reaction protocol besides epinephrine?

• A. Diphenhydramine 1 mg/kg IM/IV/IO/PO; max 50 mg
• B. Furosemide 20 mg
• C. Morphine 2 mg
• D. Acetaminophen 500 mg

Answer: (A)

In a moderate to severe allergic reaction, the key idea is that epinephrine addresses the life-threatening aspects like airway swelling, bronchospasm, and shock, making it the essential first intervention. Diphenhydramine is added as an antihistamine to blunt histamine-driven symptoms such as hives, itching, and flushing that may continue even after epinephrine is given. Its role is supportive and targets the downstream effects of histamine release, with a dosing of 1 mg/kg up to a maximum of 50 mg by the most appropriate route ( IM/IV/IO/PO ). The other options don’t fit this scenario: furosemide is a diuretic with no role in an acute allergic reaction; morphine is an analgesic that can worsen respiratory status and trigger histamine release; acetaminophen doesn’t affect the allergic process.