What is the treatment for anaphylaxis?

Anaphylaxis Treatment

Intramuscular epinephrine is the first-line treatment for anaphylaxis and must be administered immediately upon recognition of symptoms, without delay. 1, 2

First-Line Treatment

1. Epinephrine Administration:

   • Route: Intramuscular (IM) injection in the anterolateral mid-thigh
   • Dosage:
     • Adults and children ≥30 kg: 0.3-0.5 mg of 1:1000 concentration (1 mg/mL)
     • Children <30 kg: 0.01 mg/kg of 1:1000 concentration, maximum 0.3 mg 1
   • Timing: Administer immediately upon recognition of anaphylaxis
   • Repeat: May repeat every 5-15 minutes if symptoms persist

2. Patient Positioning:

   • Place patient in supine position with legs elevated if hypotensive 1
   • Maintain airway if vomiting or respiratory distress occurs

Supportive Measures (After Epinephrine)

1. Airway Management:

   • Assess airway patency
   • Provide supplemental oxygen if needed
   • Consider advanced airway management for severe cases

2. Fluid Resuscitation:

   • IV fluid resuscitation with 1-2 liters of normal saline
   • Initial bolus: 5-10 mL/kg in first 5 minutes 1
   • Continue as needed based on hemodynamic response

3. Adjunctive Medications (only after epinephrine):

   • Antihistamines:
     • H1 antagonists: Diphenhydramine 25-50 mg IV/IM (adults) or 1-2 mg/kg (children)
     • H2 antagonists: Ranitidine 1 mg/kg IV 1
   • Corticosteroids:
     • Methylprednisolone 1-2 mg/kg IV every 6 hours or
     • Prednisone 0.5 mg/kg orally for less severe cases 1
   • Bronchodilators:
     • Albuterol 2.5-5 mg via nebulizer for persistent bronchospasm 1

Monitoring and Observation

1. Vital Signs Monitoring:

   • Continuous cardiac monitoring
   • Regular assessment of blood pressure, heart rate, and oxygen saturation

2. Observation Period:

   • All patients should be observed for at least 4-6 hours after symptom resolution
   • Extended observation (8-24 hours) for:
     • Severe reactions
     • Patients requiring multiple epinephrine doses
     • Patients with risk factors for biphasic reactions 1, 3

Important Clinical Considerations

• No absolute contraindications exist for using epinephrine in anaphylaxis, even in elderly patients or those with cardiac disease 1
• Failure to administer epinephrine promptly is associated with increased mortality 4
• Intramuscular route is preferred over subcutaneous (delayed onset) or intravenous (increased risk of adverse effects) 4
• Biphasic reactions occur in approximately 5% of cases, with higher risk in severe anaphylaxis or cases requiring multiple epinephrine doses 3
• The evidence does not support routine use of antihistamines and/or glucocorticoids to prevent biphasic anaphylaxis, though they may help manage symptoms 3

Discharge Planning and Follow-up

1. Prescribe epinephrine auto-injector with proper training on use
2. Provide anaphylaxis emergency action plan
3. Refer to allergist/immunologist for identification of triggers and long-term management
4. Recommend medical identification jewelry or wallet card 1

Common Pitfalls to Avoid

• Delaying epinephrine administration while giving antihistamines first
• Using incorrect route (subcutaneous instead of intramuscular)
• Inadequate observation period after symptom resolution
• Failure to prescribe auto-injector at discharge
• Insufficient patient education about trigger avoidance and emergency management

The evidence consistently emphasizes that prompt administration of epinephrine is the cornerstone of anaphylaxis management, with delays potentially resulting in fatal outcomes 4, 5, 6. Despite this, studies show that many clinicians remain uncertain about proper dosing and administration 7, highlighting the need for clear protocols in emergency settings.