What are the treatment options for allergic reactions?

Treatment Options for Allergic Reactions

Epinephrine is the first-line treatment for anaphylaxis and should be administered promptly without delay for any severe allergic reaction, as delayed administration has been implicated in contributing to fatalities. 1

Classification and Treatment Algorithm

Severe Allergic Reactions (Anaphylaxis)

Anaphylaxis is characterized by:

• Respiratory symptoms (difficulty breathing, wheezing, stridor)
• Cardiovascular symptoms (hypotension, tachycardia)
• Skin symptoms (widespread urticaria, angioedema)
• GI symptoms (vomiting, diarrhea, abdominal cramps)

Treatment Protocol:

1. First-line treatment:

   • Epinephrine IM injection in anterior-lateral thigh 1, 2
     • Weight 10-25 kg: 0.15 mg epinephrine autoinjector
     • Weight >25 kg: 0.3 mg epinephrine autoinjector
     • Alternative: Epinephrine (1:1000 solution) 0.01 mg/kg; maximum 0.5 mg per dose
   • May repeat every 5-15 minutes if symptoms persist

2. Concurrent actions:

   • Eliminate allergen exposure
   • Call for emergency help (911)
   • Place patient in recumbent position with lower extremities elevated
   • Provide supplemental oxygen
   • Administer IV fluids for volume resuscitation 1

3. Adjunctive treatments:

   • Bronchodilator (albuterol) for bronchospasm
   • H1 antihistamine: diphenhydramine 1-2 mg/kg (max 50 mg)
   • H2 antihistamine: ranitidine 1-2 mg/kg
   • For refractory cases: consider vasopressors, glucagon (1-5 mg IV for epinephrine-unresponsive patients), or atropine for bradycardia 1

4. Post-stabilization care:

   • Transfer to emergency facility
   • Observe for 4-6 hours minimum 1
   • Monitor vital signs every 15 minutes until resolution

Mild-to-Moderate Allergic Reactions

Characterized by:

• Localized urticaria
• Mild angioedema
• Pruritus
• Flushing
• Mild oral symptoms

Treatment Protocol:

1. First-line treatment:

   • H1 antihistamines 1, 3
     • Diphenhydramine 1-2 mg/kg (max 50 mg) for rapid relief
     • OR second-generation antihistamines (cetirizine, fexofenadine, loratadine) for less sedation 4

2. Additional treatments:

   • H2 antihistamines (ranitidine) may provide additional benefit, especially for urticaria 5
   • Continued observation to ensure symptoms don't progress

3. Important caution:

   • If symptoms progress or patient has history of severe reactions, administer epinephrine immediately 1

Discharge Planning After Allergic Reaction

For patients who experienced anaphylaxis:

1. Provide anaphylaxis emergency action plan
2. Prescribe epinephrine autoinjector (2 doses)
3. Educate on autoinjector use and expiration monitoring
4. Continue adjunctive treatment:
   • H1 antihistamine: diphenhydramine every 6 hours for 2-3 days or non-sedating alternative
   • H2 antihistamine: ranitidine twice daily for 2-3 days
   • Corticosteroid: prednisone daily for 2-3 days 1
5. Arrange follow-up with primary care and allergist/immunologist

Important Clinical Considerations

Common Pitfalls to Avoid:

1. Delaying epinephrine administration - This is the most common error in anaphylaxis management and increases mortality risk 6
2. Relying solely on antihistamines for anaphylaxis - Antihistamines cannot reverse airway obstruction, hypotension, or shock 6
3. Using sedating first-generation antihistamines - Second-generation antihistamines (cetirizine, fexofenadine) are preferred for non-emergency allergic reactions due to less sedation and impairment 7, 4
4. Improper patient positioning - Patients with hypotension should be placed in recumbent position with legs elevated 1
5. Insufficient observation period - Patients with anaphylaxis require at least 4-6 hours of observation due to risk of biphasic reactions 1

High-Risk Patients:

• Adolescents and young adults
• Patients with known food allergy and previous anaphylaxis
• Patients with asthma, especially poorly controlled
• Patients with allergy to peanuts or tree nuts 1

Remember that while systemic corticosteroids are often recommended to prevent biphasic reactions, there is limited evidence supporting their effectiveness for this purpose 1.