What is the recommended management for an allergic reaction?

Management of Allergic Reactions

Epinephrine is the first-line treatment for anaphylaxis and should be administered immediately upon recognition of symptoms, with no absolute contraindications to its use in this life-threatening condition. 1, 2

Classification and Initial Management

Mild to Moderate Allergic Reactions

• Symptoms: Flushing, urticaria, isolated mild angioedema, pruritus
• Treatment:
  • H1 antihistamines (first-line for mild reactions)
    • Preferred: Second-generation (non-sedating) antihistamines like cetirizine, loratadine, or fexofenadine 3
    • Alternative: Diphenhydramine 1-2 mg/kg (maximum 50 mg) orally every 6 hours for 2-3 days 1
  • H2 antihistamines can be added (e.g., ranitidine twice daily for 2-3 days) 1
  • Important: Continuous monitoring is essential as mild reactions can progress to anaphylaxis 1

Severe Allergic Reactions/Anaphylaxis

• Symptoms: Respiratory distress, hypotension, widespread urticaria, significant angioedema, laryngospasm, bronchospasm
• Treatment:
  • First-line: Epinephrine IM 1, 2, 4
    • Weight 10-25 kg: 0.15 mg epinephrine autoinjector in anterior-lateral thigh
    • Weight >25 kg: 0.3 mg epinephrine autoinjector in anterior-lateral thigh
    • Alternative dosing: Epinephrine (1:1000 solution) 0.01 mg/kg IM, maximum 0.5 mg
    • May need to repeat doses every 5-15 minutes if symptoms persist

Adjunctive Treatments (Only After Epinephrine for Anaphylaxis)

1. Bronchodilators (for bronchospasm)

   • Albuterol via MDI or nebulizer 1

2. Antihistamines (not a substitute for epinephrine in anaphylaxis)

   • H1 antihistamines: Diphenhydramine or second-generation alternatives 1, 3
   • H2 antihistamines: Ranitidine 1

3. Corticosteroids (may help prevent biphasic reactions, though evidence is limited)

   • Prednisone daily for 2-3 days 1

4. Supportive care

   • Supplemental oxygen if needed
   • IV fluids for hypotension
   • Place patient in recumbent position with lower extremities elevated if tolerated 1

Post-Treatment Management

Observation Period

• All patients who receive epinephrine should be transferred to an emergency facility 1
• Observe for 4-6 hours after successful treatment 1
• Longer observation or hospital admission for severe or refractory symptoms 1
• Monitor for biphasic reactions (can occur up to 72 hours later) 1

Discharge Plan After Anaphylaxis

1. Provide emergency action plan 1, 5
2. Prescribe epinephrine autoinjector (2 doses) 1, 4, 6
3. Continue medications for 2-3 days 1
   • H1 antihistamine (consider switching to non-sedating option) 3
   • H2 antihistamine
   • Corticosteroid
4. Schedule follow-up with primary care provider and consider referral to allergist/immunologist 1
5. Recommend medical identification jewelry for patients at risk 1

High-Risk Patients

Special attention should be given to patients with:

• Previous history of anaphylaxis
• Asthma (especially poorly controlled)
• Known allergy to peanuts, tree nuts, fish, or shellfish
• Mast cell disorders
• Cardiovascular disease 1, 7

Common Pitfalls to Avoid

• Delaying epinephrine administration - this is associated with increased mortality 1, 4, 8
• Using antihistamines alone for anaphylaxis - they are not sufficient and may delay proper treatment 1, 3
• Failing to prescribe autoinjectors - patients at risk should carry two doses at all times 1, 6
• Inadequate observation time - patients should be monitored for potential biphasic reactions 1
• Insufficient patient education - patients need clear instructions on allergen avoidance and when/how to use epinephrine 1, 5

Remember that there are no absolute contraindications to epinephrine in anaphylaxis, as the risk of death from untreated anaphylaxis outweighs potential adverse effects of epinephrine 1.