What is the management approach for allergic reactions?

Management of Allergic Reactions

Epinephrine is the first-line treatment for anaphylaxis and should be administered promptly at the onset of symptoms, as delayed administration has been implicated in contributing to fatalities. 1

Classification of Allergic Reactions

Allergic reactions can be classified based on severity:

• Grade I: Skin and mucosal signs only (generalized erythema, urticaria, angioedema) 1
• Grade II: Moderate multi-organ involvement with skin/mucosal signs, moderate hypotension, tachycardia, moderate bronchospasm, or gastrointestinal symptoms 1
• Grade III: Life-threatening involvement with severe hypotension, tachycardia/bradycardia, severe bronchospasm, with or without skin/mucosal signs 1
• Grade IV: Cardiac or respiratory arrest 1

Acute Management of Anaphylaxis

First-Line Treatment

• Administer epinephrine intramuscularly into the anterolateral thigh: 1, 2
  • Adults and children ≥30 kg: 0.3-0.5 mg (0.3-0.5 mL of 1:1000 solution)
  • Children <30 kg: 0.01 mg/kg (0.01 mL/kg), maximum 0.3 mg
  • May repeat every 5-15 minutes as necessary based on clinical response 1, 2

Adjunctive Treatments (after epinephrine administration)

• Position patient in recumbent position with lower extremities elevated if tolerated 1
• Administer oxygen therapy as needed 1
• Provide IV fluids in large volumes for hypotension or incomplete response to IM epinephrine 1
• Administer bronchodilator (albuterol) for bronchospasm: 1
  • MDI: 4-8 puffs (child), 8 puffs (adult) or
  • Nebulized solution: 1.5 mL (child), 3 mL (adult) every 20 minutes or continuously as needed
• H1 antihistamine: diphenhydramine 1-2 mg/kg per dose, maximum 50 mg IV or oral 1, 3
• Consider H2 antihistamine (e.g., ranitidine) as additional therapy 1
• Consider corticosteroids to potentially prevent biphasic reactions, although evidence for this is limited 1

Management Based on Reaction Severity

Mild Allergic Reactions (Grade I)

• Isolated urticaria, mild angioedema, or symptoms of oral allergy syndrome can be treated with H1 antihistamines 1
• Continue observation and monitoring to ensure symptoms don't progress 1
• If there's a history of prior severe reactions, consider early epinephrine administration even with mild symptoms 1

Severe Allergic Reactions/Anaphylaxis (Grades II-IV)

• Immediate IM epinephrine is essential 1
• For persistent hypotension despite IM epinephrine, consider continuous epinephrine infusion 1
• Transfer to emergency facility for observation and further treatment 1

Observation Period

• All patients who receive epinephrine should be observed in a medical facility 1
• Recommended observation period is 4-6 hours for most patients 1
• Longer observation or hospital admission is warranted for patients with severe or refractory symptoms 1
• Monitor for biphasic reactions, which occur in 1-20% of anaphylaxis episodes, typically around 8 hours after the initial reaction 1, 4

Discharge Planning After Anaphylaxis

All patients who have experienced anaphylaxis should be discharged with: 1

• Anaphylaxis emergency action plan 1
• Epinephrine auto-injector prescription (2 doses) with proper training on use 1
• Plan for monitoring auto-injector expiration dates 1
• Continuation of adjunctive treatment: 1
  • H1 antihistamine: diphenhydramine every 6 hours for 2-3 days or non-sedating second-generation antihistamine
  • H2 antihistamine: ranitidine twice daily for 2-3 days
  • Corticosteroid: prednisone daily for 2-3 days
• Follow-up appointment with primary healthcare provider and referral to allergist 1, 4

Special Considerations

Risk Factors for Severe Reactions

• Adolescents and young adults 1
• Known food allergy with previous history of anaphylaxis 1
• Asthma, especially poorly controlled 1
• Peanut and tree nut allergies 1
• Delayed use or improper dosing of epinephrine 1, 4

Patients Who May Need Special Attention

While there are no absolute contraindications to epinephrine in anaphylaxis, careful consideration may be needed for patients: 1

• With cardiovascular disease 1
• Taking monoamine oxidase inhibitors or tricyclic antidepressants 1
• Taking stimulant medications or cocaine 1
• With conditions like recent intracranial surgery, aortic aneurysm, uncontrolled hyperthyroidism, or hypertension 1

Common Pitfalls to Avoid

• Delaying epinephrine administration, which is associated with increased mortality 1, 4
• Using antihistamines as first-line treatment instead of epinephrine for anaphylaxis 1, 4
• Failing to observe patients adequately after treatment (minimum 4-6 hours) 1
• Not prescribing epinephrine auto-injectors for at-risk patients 1
• Discharging patients without a clear emergency action plan 1