What are the three common symptoms of an allergic reaction?

• A. Tachypnea, tachycardia, hypotension
• B. Nausea, vomiting, diarrhea
• C. Cough, wheeze, chest pain
• D. Fever, rash, fatigue

Answer: (A)

When a severe allergic reaction (anaphylaxis) affects the body, the most telling signs involve both the respiratory and circulatory systems. The airways react with swelling and bronchospasm, so the person tends to breathe rapidly—tachypnea. At the same time, the heart races to compensate for the falling blood pressure and perfusion, giving you tachycardia. The widespread reaction also makes blood vessels leak and dilate, which lowers blood pressure—hypotension. Together, these three signs form a common, recognizable pattern of a systemic allergic reaction progressing toward anaphylaxis.

Other options describe symptoms that can appear in various contexts of illness or allergy but aren’t the typical three-wall pattern you’d expect in a systemic reaction. Nausea, vomiting, and diarrhea are GI symptoms that may occur with many conditions; cough and wheeze can occur with airway involvement but don’t inherently indicate the circulatory collapse seen with anaphylaxis; fever and rash can accompany many illnesses and allergies but fever is not a hallmark feature of acute allergic reactions in the same way as the rapid breathing, rapid heart rate, and low blood pressure.