In a systemic Hymenoptera reaction, what is the first-line treatment?

In a systemic Hymenoptera reaction, what is the first-line treatment?

• A. Diphenhydramine
• B. Steroids
• C. Epinephrine IM
• D. Albuterol

Answer: (C)

The main idea is that in a systemic Hymenoptera reaction (anaphylaxis), the immediate life-saving treatment is epinephrine given by intramuscular injection. Epinephrine acts quickly on multiple receptors to reverse the life-threatening features of anaphylaxis: it constricts peripheral blood vessels to raise blood pressure and reduce airway edema (alpha-1 effect), improves cardiac output (beta-1 effect), and opens the airways by relaxing bronchial smooth muscle (beta-2 effect) while also dampening mediator release from mast cells. This rapid, multi-pronged action addresses the key problems you see in anaphylaxis: airway compromise, bronchospasm, and shock. While antihistamines and steroids can help with symptoms, they do not act quickly enough to prevent deterioration, and steroids take hours to become effective. Albuterol can help with bronchospasm but does not treat the underlying airway edema or hypotension. Therefore, epinephrine is the first-line treatment, with dosing typically 0.3–0.5 mg of 1:1000 epinephrine IM in adults (repeating as needed) and weight-based dosing in children, along with supportive measures as needed.

The main idea is that in a systemic Hymenoptera reaction (anaphylaxis), the immediate life-saving treatment is epinephrine given by intramuscular injection. Epinephrine acts quickly on multiple receptors to reverse the life-threatening features of anaphylaxis: it constricts peripheral blood vessels to raise blood pressure and reduce airway edema (alpha-1 effect), improves cardiac output (beta-1 effect), and opens the airways by relaxing bronchial smooth muscle (beta-2 effect) while also dampening mediator release from mast cells. This rapid, multi-pronged action addresses the key problems you see in anaphylaxis: airway compromise, bronchospasm, and shock.

While antihistamines and steroids can help with symptoms, they do not act quickly enough to prevent deterioration, and steroids take hours to become effective. Albuterol can help with bronchospasm but does not treat the underlying airway edema or hypotension. Therefore, epinephrine is the first-line treatment, with dosing typically 0.3–0.5 mg of 1:1000 epinephrine IM in adults (repeating as needed) and weight-based dosing in children, along with supportive measures as needed.