What are the discharge instructions for a patient released from the Emergency Room (ER) after an allergic reaction?

Discharge Instructions for Allergic Reaction from the Emergency Room

All patients discharged from the ER after an allergic reaction must receive an epinephrine auto-injector prescription with hands-on training before leaving, regardless of reaction severity. 1

Immediate Discharge Medications

Continuation Therapy (2-3 Days Post-Discharge)

• H1 antihistamine: Diphenhydramine every 6 hours for 2-3 days, or alternatively a non-sedating second-generation antihistamine (cetirizine 10 mg daily, loratadine 10 mg daily, or fexofenadine 180 mg daily) 1, 2
• H2 antihistamine: Ranitidine twice daily for 2-3 days 1, 2
• Corticosteroid: Prednisone daily for 2-3 days (0.5-1 mg/kg/day, typically 40-60 mg for adults) 1, 2

Important caveat: While corticosteroids are commonly prescribed, evidence supporting their use to prevent biphasic reactions is limited, though they may help with recurrent urticaria and eczema flares. 1, 3

Epinephrine Auto-Injector Requirements

Prescription and Training

• Provide two epinephrine auto-injectors (0.15 mg for patients 10-25 kg; 0.3 mg for patients >25 kg) 1
• Conduct hands-on training on proper administration technique before discharge 1
• Instruct on storage: Keep at room temperature to prevent medication degradation 1
• Set up automated pharmacy reminders for prescription renewal and expiration date monitoring 1

When to Use Epinephrine

• At the first sign of recurrence of allergic symptoms, self-administer epinephrine immediately, then call 911 or go to the nearest emergency facility 1
• Emphasize that epinephrine should be given early if symptoms progress or if there is any respiratory difficulty, widespread urticaria, or facial/throat swelling 2

Written Emergency Action Plan (SAFE Mnemonic)

Provide printed materials covering these four critical elements: 1

S - Seek Support

• Warn patients they are at risk for repeat episodes of anaphylaxis in the future 1
• Instruct to use epinephrine and immediately seek emergency care if symptoms recur 1

A - Allergen Identification and Avoidance

• Document the suspected trigger in the medical record before discharge 1, 2
• Emphasize the importance of subsequent allergy testing to verify the trigger for successful future avoidance 1

F - Follow-up with Specialty Care

• Schedule follow-up with primary care within 1-2 weeks after the anaphylaxis event 1
• Provide allergist/immunologist referral for comprehensive evaluation, testing, and long-term management 1
• Direct communication between the ER physician and primary care provider is recommended to ensure appropriate follow-up 1

E - Epinephrine for Emergencies

• Reiterate auto-injector prescription, proper use, and expiration date monitoring 1

Expected Post-Discharge Symptoms

Common Delayed Manifestations

• Recurrent urticaria may persist for 1-2 days after significant cutaneous reactions—this is expected and does not indicate treatment failure 1, 2, 3
• Loose stools or diarrhea may occur over the next 24 hours following immediate-type reactions 1, 3
• Eczema flares may persist for several days after allergic reactions involving skin manifestations 1

Biphasic Reaction Warning

• Biphasic reactions occur in 1-20% of cases, typically around 8 hours after the initial reaction but can occur up to 72 hours later 3, 4
• Patients should be cautioned about this low but real risk and provided with contact information for their allergist/immunologist 1

Medical Identification

• Recommend medical identification jewelry or anaphylaxis wallet card to alert first responders in future emergencies 1
• Document the allergy prominently in the medical record (e.g., "penicillin allergy" or specific drug/food allergy) 2

Common Pitfalls to Avoid

• Do not discharge without epinephrine auto-injector prescription and training—this is a critical gap in current ER practice, with fewer than 50% of EDs providing this 5
• Do not rely solely on antihistamines or corticosteroids for future reactions—epinephrine is the only first-line treatment for anaphylaxis 1, 2
• Do not assume patients understand auto-injector use without hands-on demonstration—proper technique is essential for effectiveness 1
• Do not skip allergist referral—only 42% of EDs consistently provide this, yet it is essential for trigger identification and prevention strategies 5

Patient Education Resources

Direct patients to reliable online resources: 1

• American Academy of Allergy, Asthma and Immunology (www.aaaai.org)
• American College of Allergy, Asthma and Immunology (www.acaai.org)