Discharge Treatment for Anaphylactic Shock
All patients discharged after anaphylactic shock must receive a prescription for two epinephrine auto-injectors (0.15 mg for 10-25 kg, 0.3 mg for >25 kg) with hands-on training in proper use, along with a written anaphylaxis emergency action plan and referral to an allergist-immunologist. 1, 2
Essential Discharge Prescriptions
Epinephrine Auto-Injectors (Mandatory)
- Prescribe two doses of epinephrine auto-injector at discharge for all patients 1, 2
- Dosing: 0.15 mg for patients weighing 10-25 kg; 0.3 mg for patients weighing ≥25 kg 1, 2, 3
- Provide hands-on training in proper auto-injector technique before discharge 1, 2
- Establish a plan for monitoring expiration dates 1, 2
Adjunctive Medications (Optional 2-3 Day Course)
While the evidence for preventing biphasic reactions is weak, the following may be prescribed for symptom management:
H1 Antihistamine:
- Diphenhydramine every 6 hours for 2-3 days 1, 2
- Dosing: 1-2 mg/kg per dose (maximum 50 mg) 1, 2
- Alternative: non-sedating second-generation antihistamine 1
H2 Antihistamine:
Corticosteroid:
Critical Caveat About Adjunctive Medications
Antihistamines and corticosteroids should NOT be relied upon to prevent biphasic anaphylaxis. 1 The 2020 practice parameter update found very low-quality evidence and suggests against using these medications specifically as interventions to prevent biphasic reactions, though they may provide symptomatic relief 1. These medications have delayed onset (1-3 hours for antihistamines, 4-24 hours for corticosteroids) compared to epinephrine (<10 minutes) 4, 5.
Required Patient Education Components
Written Anaphylaxis Emergency Action Plan
- Provide detailed instructions on trigger avoidance 1, 2
- Include early recognition of anaphylaxis symptoms 1, 2
- Specify when and how to self-administer epinephrine 1, 2
Medical Identification
Biphasic Reaction Education
- Educate about biphasic reactions, which occur in 1-20% of cases 1, 2
- Symptoms typically recur around 8 hours but can occur up to 72 hours after initial reaction 1, 2
- Risk factors include severe initial presentation, requiring >1 dose of epinephrine, wide pulse pressure, unknown trigger, and drug triggers in children 1, 2
Follow-Up Arrangements
Allergist-Immunologist Referral (Strongly Recommended)
All patients should receive consultation from an allergist-immunologist for comprehensive evaluation, allergy diagnostic testing, identification of triggers, and long-term management planning 1, 2
Primary Care Follow-Up
Observation Period Before Discharge
- Minimum observation: 4-6 hours for most patients after complete symptom resolution 1, 2
- Extended observation or admission is warranted for: 1, 2
- Severe initial anaphylaxis requiring >1 dose of epinephrine
- Refractory symptoms
- Coexisting severe asthma
- Cardiovascular disease
- Delayed epinephrine administration
- Unknown trigger
- Limited access to emergency medical services
- Poor self-management skills
The number needed to monitor with extended observation to detect one biphasic episode is 41 for severe presentations and 13 for those requiring multiple epinephrine doses 1.
Common Pitfalls to Avoid
- Never discharge without epinephrine auto-injectors - delayed epinephrine administration is associated with fatalities 1, 6
- Do not rely on antihistamines or corticosteroids alone - these do not address the life-threatening cardiovascular and respiratory manifestations 1, 5
- Avoid premature discharge - patients with severe reactions or multiple epinephrine doses require extended monitoring 1, 2
- Do not skip allergist referral - specialist evaluation is essential for trigger identification and prevention strategies 1