First-line treatment for anaphylaxis?

• A. Epinephrine
• B. Histamine
• C. Leukotrienes
• D. SIRS

Answer: (A)

Epinephrine is used first because it rapidly reverses the life-threatening features of anaphylaxis by acting on multiple receptor systems. Activation of alpha-1 receptors tightens blood vessels to raise blood pressure and reduce mucosal swelling; beta-2 stimulation relaxes airway smooth muscle to relieve bronchospasm and improve airflow; beta-1 effects increase heart rate and contractility to boost perfusion. It also helps limit further release of mediators from mast cells. This combination tackles the core problems of anaphylaxis—airway obstruction, swelling, and hypotension—faster than any other intervention, which is why it’s given immediately when anaphylaxis is suspected. Administer intramuscularly into the mid-thigh as soon as possible. Typical dosing is about 0.3–0.5 mg for adults; for children, 0.01 mg/kg up to around 0.3 mg, with repeats every 5–15 minutes if needed. If symptoms persist, escalate to advanced care with airway support, high-flow oxygen, and IV fluids, and consider a monitored epinephrine infusion if necessary. Antihistamines and steroids can help but do not act quickly enough to replace epinephrine.