What is the treatment for anaphylaxis?

Treatment of Anaphylaxis

Epinephrine is the first-line treatment for anaphylaxis and should be administered immediately upon recognition of symptoms, with no absolute contraindications even in patients with comorbidities such as cardiac disease, advanced age, or frailty. 1, 2, 3

First-Line Management

• Stop the offending agent or trigger if ongoing (such as contrast media infusion) 1
• Administer epinephrine intramuscularly into the vastus lateralis (anterolateral thigh):
  • Adult dose: 0.01 mg/kg of 1:1000 concentration (1 mg/mL) to a maximum of 0.5 mg 1, 2, 3
  • Pediatric dose: 0.01 mg/kg of 1:1000 concentration to a maximum of 0.3 mg 2, 3
• Epinephrine can be repeated every 5-15 minutes if symptoms persist 2
• Epinephrine autoinjectors may be used with doses of 0.3 mg for patients >30 kg and 0.15 mg for children <25-30 kg 1, 2

Positioning and Supportive Care

• Place patient in supine or Trendelenburg position if hypotensive 1
• Begin fluid resuscitation immediately for patients with hypotension 1
• Administer supplemental oxygen for respiratory symptoms 1
• Continuously monitor vital signs and reassess the clinical scenario 1

Second-Line Treatments (after epinephrine administration)

• H1 antihistamines (e.g., diphenhydramine 25-50 mg IV) for cutaneous symptoms 2, 3
• H2 antihistamines (e.g., ranitidine 50 mg IV) may be added 2, 3
• Bronchodilators (e.g., albuterol) for persistent bronchospasm 3
• Glucocorticoids may be considered for severe or prolonged anaphylaxis, though they have slow onset of action 3

Management of Severe or Refractory Anaphylaxis

• For protracted anaphylaxis unresponsive to IM epinephrine, consider IV epinephrine (1:10,000 concentration [1 mg/10 mL]) 1
• For persistent hypotension despite epinephrine and fluids, consider vasopressor infusion 3
• For patients on β-blockers with refractory symptoms, consider glucagon 3

Post-Anaphylaxis Management

• Observe patients for at least 6 hours due to risk of biphasic reactions 2, 4
• Longer observation (8-24 hours) may be needed for severe reactions or those with risk factors 3, 4
• Refer to an allergist for follow-up and consideration of immunotherapy if appropriate 4
• Prescribe epinephrine autoinjectors for patients at risk of future anaphylaxis 5, 6

Common Pitfalls to Avoid

• Delaying epinephrine administration, which increases risk of fatality and biphasic reactions 1, 3
• Using subcutaneous instead of intramuscular injection, which delays absorption 3
• Relying solely on antihistamines or glucocorticoids without administering epinephrine first 2, 3
• Failing to distinguish anaphylaxis from vasovagal reactions (anaphylaxis typically presents with tachycardia and cutaneous symptoms, while vasovagal reactions present with immediate bradycardia and absence of skin manifestations) 1
• Administering intravenous epinephrine outside of monitored settings (except in cardiac arrest or profound hypotension unresponsive to IM epinephrine) 3