Clinical features

Cutaneous—pruritus, urticaria, angioedema.
Gastrointestinal—abdominal cramping, diarrhea.
Vascular—hypotension.
Respiratory—respiratory distress due to laryngeal edema, laryngospasm, or bronchospasm.

Immediate treatment

Initiate code blue.
Assess airway, breathing, and circulation.
Administer epinephrine 0.3-0.5 mg (0.3-0.5 ml of a 1:1000 solution) IM or SC.
Repeat injections at 10- to 20-min intervals if necessary. Injection in the anterolateral thigh may lead to more predictable and rapid absorption compared with sites in the arm.
Airway maintenance is a priority and endotracheal intubation or tracheostomy may be necessary.
Antihistamines such as diphenhydramine (25-50 mg p.o./IV/IM) and ranitidine (150 mg p.o. q12h or 50 mg IM/IV q6-8 h) may shorten the duration of the reaction and ameliorate the cutaneous manifestations and gastrointestinal and uterine smooth muscle spasms.
Respiratory therapy, albuterol/ipratropium bromide (Atrovent) nebulizers.
Volume expansion with IV fluids may be necessary if the patient remains hypotensive.
Observation for a minimum of 6 h is indicated for mild reactions.
Moderate to severe reactions warrant hospitalization and close observation for 24 h.

Prevention

Identify the offending antigen.
Record the offending antigen and document anaphylactic reaction.
Ensure the chart is prominently marked to avoid exposure to the offending antigen during subsequent visits.
Counsel patient regarding avoidance of the offending antigen and immediate management of future anaphylactic reactions.
Refer patient to medicine or allergy/immunology for further evaluation and long-term prophylactic treatment as indicated.
Self-administered epinephrine may be prescribed for patients with a history of anaphylaxis.