Anaphylaxis Discharge Medications
All patients discharged after anaphylaxis must receive two epinephrine auto-injectors with hands-on training, plus a 2-3 day course of adjunctive medications including an H1 antihistamine, H2 antihistamine, and corticosteroid. 1, 2
Essential Prescription: Epinephrine Auto-Injectors
Every patient must leave with two doses of epinephrine auto-injector—this is non-negotiable. 1, 2
Dosing by Weight:
Critical Requirements:
- Provide hands-on demonstration and have the patient demonstrate proper technique back to you before discharge 1, 2
- Establish a system for monitoring expiration dates 1, 2
- Prescribe two devices because a second dose may be needed if symptoms persist or recur 2
Adjunctive Medications (2-3 Day Course)
Despite limited evidence for preventing biphasic reactions, guidelines recommend a short course of adjunctive medications. 2
H1 Antihistamine:
- Diphenhydramine: 1-2 mg/kg every 6 hours (maximum 50 mg per dose) for 2-3 days 1, 2
- Alternative: Non-sedating second-generation antihistamine may be substituted 1
H2 Antihistamine:
- Ranitidine: 1 mg/kg twice daily for 2-3 days 1, 2
- Note: The combination of H1 and H2 antihistamines is superior to H1 alone during acute treatment 1
Corticosteroid:
- Prednisone: 0.5 mg/kg daily for 2-3 days 1, 2
- For severe episodes: Consider higher doses equivalent to methylprednisolone 1-2 mg/kg/day 1
Important Caveat:
The evidence supporting corticosteroids and antihistamines for preventing biphasic anaphylaxis is weak and contradictory. 2 These medications have not been proven to prevent recurrent reactions, but are recommended based on expert consensus and their potential benefit in protracted anaphylaxis. 1
Mandatory Discharge Documentation
Written Anaphylaxis Emergency Action Plan:
- Detailed instructions on trigger avoidance 1, 2
- Early symptom recognition 1, 2
- Step-by-step epinephrine administration instructions 1
- When to call emergency services 1
Medical Identification:
Patient Education Must Include:
- Biphasic reactions: Can occur up to 72 hours later, typically around 8 hours after initial reaction 1, 2
- Symptoms may recur without re-exposure to the allergen 3
- Immediate epinephrine use at first sign of recurrence 1
Follow-Up Arrangements
Immediate Follow-Up:
- Schedule appointment with primary care provider 1, 2
- Strongly recommend referral to allergist/immunologist for comprehensive evaluation, trigger identification, and long-term management planning 1, 2, 3
Observation Period Before Discharge:
- Minimum 4-6 hours for most patients 1, 2, 3
- Prolonged observation or admission required for: 1, 2
- Severe or refractory symptoms requiring multiple epinephrine doses
- History of biphasic reactions
- Coexisting severe or poorly controlled asthma
- Underlying cardiovascular disease
- Delayed epinephrine administration during acute episode
Common Pitfalls to Avoid
- Never discharge without two epinephrine auto-injectors—patients frequently fail to use them when needed, and a second dose is often required 4
- Never assume patients understand how to use the auto-injector—studies show deficient knowledge even after prescription 4
- Never skip the written action plan—verbal instructions alone are insufficient 1, 2
- Do not rely solely on adjunctive medications—epinephrine is the only life-saving medication; antihistamines and steroids are secondary 1, 5, 6
- Do not discharge patients with ongoing symptoms or within 4 hours unless they have had a very mild reaction 1, 2