Treatment: Anaphylaxis

Mild symptoms such as pruritus and urticaria can be controlled by administration of 0.3-0.5 mL of 1:1000 (1.0 mg/mL) epinephrine SC or IM, with repeated doses as required at 5- to 20-min intervals for a severe reaction.

An IV infusion should be initiated for administration of 2.5 mL of 1:10,000 epinephrine solution at 5- to 10-min intervals, and volume expanders such as normal saline, and vasopressor agents, e.g., dopamine, if intractable hypotension occurs.

Epinephrine provides both α- and β-adrenergic effects, resulting in vasoconstriction and bronchial smooth-muscle relaxation. Beta blockers are relatively contraindicated in persons at risk for anaphylactic reactions.

The following should also be used as necessary:

• Antihistamines such as diphenhydramine 50-100 mg IM or IV.
• Nebulized albuterol or aminophylline 0.25-0.5 g IV for bronchospasm.
• Oxygen; endotracheal intubation or tracheostomy may be necessary for progressive hypoxemia.
• Glucocorticoids (methylprednisolone 0.5-1.0 mg/kg IV); not useful for acute manifestations but may help alleviate later recurrence of hypotension, bronchospasm, or urticaria.
• For antigenic material injected into an extremity consider: use of a tourniquet proximal to the site, 0.2 mL of 1:1000 epinephrine into the site, removal without compression of an insect stinger if present.