Anaphylaxis is not just an allergic reaction.
Severe anaphylaxis is a rapidly evolving cardiovascular and respiratory emergency.
The central therapy is epinephrine because epinephrine treats the physiology, not just the blood pressure.
Anaphylaxis causes mast cell and basophil mediator release. Histamine, leukotrienes, prostaglandins, platelet-activating factor, and other mediators produce vasodilation, capillary leak, bronchospasm, mucosal edema, and myocardial effects.
This can create distributive shock, obstructive respiratory failure, and airway compromise at the same time.