Anaphylaxis Treatment Guidelines

Primary Treatment

The American Academy of Allergy, Asthma, and Immunology recommends epinephrine as the first-line medication for anaphylaxis, which should be administered immediately to treat symptoms of itching, skin erythema, tongue edema, and hypotension 1, 2, 3
Epinephrine should be administered intramuscularly into the vastus lateralis at a dose of 0.01 mg/kg of 1:1000 concentration, with a maximum single dose of 0.5 mg in adults and 0.3 mg in children and teenagers 2, 3, 4
Delay in administering epinephrine has been associated with anaphylaxis fatalities and increased risk of biphasic reactions 3

The American Academy of Allergy, Asthma, and Immunology suggests H1 antihistamines, such as diphenhydramine, can be administered as second-line therapy for anaphylaxis 1, 5, 6
Antihistamines should never be used alone or as the initial treatment for anaphylaxis 5, 3
A combination of H1 antihistamines and H2 antihistamines is superior to H1 antihistamines alone, but both are still second-line to epinephrine 5, 6

Systemic glucocorticosteroids can be considered for patients with a history of idiopathic anaphylaxis, asthma, or those experiencing severe or prolonged anaphylaxis 1, 6, 7
Glucocorticoids have no role in treating acute anaphylaxis given their slow onset of action 3
If given, intravenous glucocorticosteroids should be administered every 6 hours at a dosage equivalent to 1.0-2.0 mg/kg/day 6

For hypotension refractory to volume replacement and epinephrine injections, consider vasopressor infusion such as dopamine 1, 6
For bronchospasm resistant to epinephrine, consider nebulized albuterol 1, 6
If the patient is on β-blocker therapy, consider glucagon infusion 1, 6, 7
In cases of cardiopulmonary arrest, high-dose intravenous epinephrine may be required 7

Multiple doses of epinephrine may be required if symptoms persist or recur 8
All patients with anaphylaxis should be transported to an emergency department for further monitoring due to the risk of biphasic reactions 3, 9
Aspirin is not indicated in the treatment of anaphylaxis and may potentially worsen symptoms in patients with aspirin sensitivity 1, 5

Using subcutaneous instead of intramuscular injection of epinephrine, which delays absorption 10
Administering intravenous epinephrine outside of a monitored setting (should only be used for cardiac arrest or profound hypotension unresponsive to IM epinephrine) 1, 5
Relying solely on antihistamines or glucocorticoids for treatment of anaphylaxis 3