As a result current guidelines suggest adrenaline should be given as soon as possible.
Adrenaline has physiological benefits in the treatment of anaphylaxis:
1. stimulation of α adrenoceptors increases peripheral vascular resistance thus improving blood pressure and coronary perfusion, reversing peripheral vasodilation, and decreasing angioedema.
2. Stimulation of β1 adrenoceptors has both positive inotropic and chronotropic cardiac effects.
3. Stimulation of β2 receptors causes bronchodilation as well as increasing intracellular cyclic adenosine monophosphate production in mast cells and basophils, reducing release of inflammatory mediators.