What is the recommended treatment for anaphylaxis?

Anaphylaxis Treatment Guidelines

Epinephrine is the first-line treatment for anaphylaxis and must be administered immediately upon recognition of symptoms to prevent morbidity and mortality. 1, 2

Primary Treatment

Epinephrine Administration

• Administer epinephrine intramuscularly into the lateral thigh (vastus lateralis) as the preferred route for first-line treatment 1, 2
• The recommended dose is 0.01 mg/kg of 1:1000 (1 mg/mL) solution, with maximum single doses of:
  • Adults: 0.3-0.5 mg 1, 3
  • Children: 0.15-0.3 mg (based on weight) 1
• Epinephrine may need to be repeated every 5-15 minutes if symptoms persist or recur 1, 2
• Delay in epinephrine administration is associated with increased mortality and risk of biphasic reactions 2, 4

For Refractory Anaphylaxis

• If intravenous access is established and patient has profound hypotension, consider IV epinephrine at 0.05-0.1 mg (1:10,000 concentration) 1
• For continuous hemodynamic support, consider epinephrine infusion (5-15 μg/min) titrated to blood pressure response 1
• For patients in cardiac arrest due to anaphylaxis, standard resuscitative measures with immediate epinephrine administration take priority 1

Secondary Treatments

Antihistamines

• H1 antihistamines (diphenhydramine 25-50 mg or 1-2 mg/kg) should be administered as second-line therapy 1, 2
• H2 antihistamines (ranitidine 50 mg for adults, 1 mg/kg for children) can be added for enhanced effect 1, 2
• Important: Antihistamines should NEVER be used alone or as initial treatment for anaphylaxis 1, 2

Additional Interventions

• For bronchospasm resistant to epinephrine: Consider inhaled β-agonists (nebulized albuterol 2.5-5 mg) 1, 2
• For hypotension refractory to epinephrine and fluid resuscitation: Consider vasopressor infusion (e.g., dopamine 2-20 μg/kg/min) 1, 2
• For patients on β-blockers with refractory symptoms: Consider glucagon (1-5 mg IV over 5 minutes, followed by infusion of 5-15 μg/min) 1, 2

Glucocorticoids

• Glucocorticoids have no role in treating acute anaphylaxis but may help prevent protracted or biphasic reactions 1, 2
• Consider for patients with history of idiopathic anaphylaxis, asthma, or severe/prolonged anaphylaxis 1, 2
• If given, administer IV glucocorticosteroids at 1-2 mg/kg/day equivalent, every 6 hours 1

Patient Monitoring and Observation

• All patients should be monitored until symptoms have fully resolved 1, 2
• Extended observation is recommended for patients with:
  • Severe initial anaphylaxis presentation 1
  • Need for >1 dose of epinephrine 1, 2
  • Wide pulse pressure 1
  • Unknown anaphylaxis trigger 1
  • History of cardiovascular disease or other risk factors for fatal anaphylaxis 1, 2
• For patients without severe risk factors, discharge after 1-hour asymptomatic observation may be reasonable 1
• For high-risk patients, extended observation of up to 6 hours or longer (including hospital admission) may be appropriate 1

Common Pitfalls to Avoid

• Delaying epinephrine administration while giving antihistamines first 1, 2
• Using subcutaneous instead of intramuscular injection of epinephrine, which delays absorption 2
• Administering IV epinephrine outside of a monitored setting (should only be used for cardiac arrest or profound hypotension unresponsive to IM epinephrine) 1, 2
• Relying solely on antihistamines or glucocorticoids for treatment of anaphylaxis 1, 2
• Failing to observe patients adequately for biphasic reactions 1, 2

Post-Anaphylaxis Care

• All patients should receive education about anaphylaxis, trigger avoidance, and self-injectable epinephrine 1, 2
• Patients should be referred to an allergist for follow-up evaluation 1, 2, 4
• Prescribe epinephrine auto-injector for patients at risk of recurrent anaphylaxis 1, 2, 3