What medications should be prescribed for discharge in a patient with a type 1 hypersensitivity reaction?

Discharge Medications for Type 1 Hypersensitivity Reaction

Patients discharged after a type 1 hypersensitivity reaction should receive an epinephrine auto-injector (two doses), oral H1 antihistamine for 2-3 days, oral H2 antihistamine for 2-3 days, and oral corticosteroid for 2-3 days to prevent biphasic reactions. 1

Essential Discharge Prescriptions

Epinephrine Auto-Injector (First Priority)

• Prescribe two epinephrine auto-injectors at time of discharge 1
• Dosing based on weight:
  • 10-25 kg: 0.15 mg auto-injector 1
  • >25 kg: 0.3 mg auto-injector 1
• Provide hands-on training before discharge on proper intramuscular administration technique into the anterior-lateral thigh 1
• Establish a plan for monitoring expiration dates 1

H1 Antihistamine (Adjunctive Therapy)

• Diphenhydramine 25-50 mg every 6 hours for 2-3 days 1
• Alternative: Non-sedating second-generation antihistamine (e.g., loratadine 10 mg daily, cetirizine 10 mg daily) for 2-3 days 1
• Second-generation agents preferred if sedation is problematic, though diphenhydramine remains the guideline-recommended first choice 1

H2 Antihistamine (Adjunctive Therapy)

• Ranitidine 150 mg twice daily for 2-3 days 1
• Combined H1/H2 blockade provides more complete histamine receptor coverage than H1 antagonists alone 2

Corticosteroid (Biphasic Reaction Prevention)

• Prednisone 40-60 mg daily for 2-3 days 1, 3
• Corticosteroids are effective in preventing biphasic reactions, which can occur hours after initial symptom resolution 1
• Administer in the morning prior to 9 am to minimize adrenal suppression 3
• Short 2-3 day course does not require tapering 1

Critical Discharge Education Components

Written Anaphylaxis Emergency Action Plan

• Provide a written emergency action plan detailing when and how to self-inject epinephrine 1
• Include instructions to call 911 immediately after epinephrine administration 1
• Emphasize that epinephrine should be given at first sign of systemic symptoms (not just for severe reactions) 1

Allergen Avoidance Counseling

• Identify and document the specific trigger if known 1
• Provide detailed instructions on avoiding the allergen in various settings 1
• Recommend medical identification jewelry or anaphylaxis wallet card 1

Recognition of Biphasic Reactions

• Warn patients that symptoms can recur 4-12 hours after initial resolution despite treatment 1
• Instruct to use epinephrine auto-injector and seek emergency care if symptoms return 1
• This is the primary rationale for continuing antihistamines and corticosteroids for 2-3 days post-discharge 1

Follow-Up Arrangements

Mandatory Follow-Up

• Schedule appointment with primary care provider within 1-2 weeks 1
• Strongly consider referral to allergist/immunologist for comprehensive evaluation, skin testing, and long-term management planning 1
• Allergist can perform specific IgE testing to identify triggers and provide desensitization protocols if needed 4

Common Pitfalls to Avoid

• Do not discharge without epinephrine auto-injector prescription and training - this is the most critical intervention for preventing death from future reactions 1
• Do not prescribe antihistamines alone without corticosteroids - corticosteroids are specifically indicated to prevent biphasic reactions 1
• Do not use first-generation H1 antihistamines (diphenhydramine) as monotherapy for acute reactions - they have slow onset and cannot replace epinephrine 2
• Avoid prescribing only a single epinephrine auto-injector - two doses are required as 10-20% of patients need a second dose 1