What medication and discharge instructions should be provided to a patient after an anaphylaxis reaction?

Anaphylaxis Discharge Medications and Instructions

All patients discharged after anaphylaxis must receive two epinephrine auto-injectors (0.15 mg for 10-25 kg, 0.3 mg for >25 kg), hands-on training in their use, a written emergency action plan, and referral to an allergist-immunologist. 1, 2

Essential Discharge Prescription: Epinephrine Auto-Injectors

• Prescribe two doses of epinephrine auto-injector at discharge (not just one) to ensure availability if a second dose is needed before emergency services arrive 1, 2

• Dosing is weight-based: 0.15 mg for patients weighing 10-25 kg and 0.3 mg for patients weighing >25 kg 1, 2, 3

• Provide hands-on training with a placebo trainer device before discharge - studies show that 75% of medical professionals cannot correctly demonstrate the three steps of injection, highlighting the critical need for direct patient education 1, 2, 4

• Establish a monitoring plan for expiration dates (auto-injectors expire after 1 year) and instruct patients to check that the liquid remains clear 1, 2

Adjunctive Discharge Medications (2-3 Day Course)

While the evidence for preventing biphasic reactions is weak, adjunctive medications may provide symptomatic relief and are recommended by NIAID guidelines:

• H1 antihistamine (diphenhydramine): 1-2 mg/kg per dose (maximum 50 mg) every 6 hours for 2-3 days, or alternatively a non-sedating second-generation antihistamine 1, 2

• H2 antihistamine (ranitidine): Twice daily for 2-3 days 1, 2

• Corticosteroid (prednisone): 0.5 mg/kg daily for 2-3 days 1, 2

Critical Caveat About Adjunctive Medications

The 2020 JTFPP practice parameter found no clear evidence that glucocorticoids or antihistamines prevent biphasic anaphylaxis and suggests against their use specifically for biphasic prevention, though they may be considered for secondary symptom management (e.g., antihistamines for urticaria and itching) 1, 2

Mandatory Discharge Education Components

• Written anaphylaxis emergency action plan detailing when and how to self-inject epinephrine, trigger avoidance strategies, and early recognition of symptoms 1, 2

• Education on biphasic reactions: Inform patients that symptoms can recur after initial resolution, typically around 8 hours but potentially up to 72 hours later, occurring in 1-20% of cases 1, 2

• Medical identification jewelry or anaphylaxis wallet card to alert emergency responders 1, 2

• Printed information about anaphylaxis and its treatment 1

Follow-Up Care Requirements

• Schedule follow-up with primary care provider after the anaphylactic reaction 1, 2

• Refer to an allergist-immunologist for comprehensive evaluation, diagnostic testing, identification of triggers, and long-term management planning 1, 2

Observation Period Before Discharge

Observe for 4-6 hours after symptom resolution for most patients 1, 2

Extended observation (>6 hours) or hospital admission is indicated for:

• Severe initial anaphylaxis requiring multiple doses of epinephrine (number needed to monitor = 13 to detect one biphasic reaction) 1, 2

• Severe index presentation (number needed to monitor = 41 to detect one biphasic reaction) 1

• Refractory symptoms despite treatment 1, 2

• Risk factors for anaphylaxis fatality: cardiovascular comorbidity, poorly controlled asthma, lack of access to epinephrine or emergency services, poor self-management skills 1, 2

• Wide pulse pressure, unknown trigger, or drug trigger in children 1, 2

For patients without severe risk features, discharge after 1 hour of asymptomatic observation may be reasonable 1

Common Pitfalls to Avoid

• Do not discharge without hands-on auto-injector training - verbal instructions alone are insufficient given the high failure rate even among trained professionals 1, 4

• Do not prescribe only one epinephrine auto-injector - two doses are required as 13-41% of patients with severe features may experience biphasic reactions 1, 2

• Do not rely on antihistamines or corticosteroids to prevent biphasic reactions - these medications lack evidence for this indication and should not replace proper observation and epinephrine availability 1, 2

• Do not discharge without allergist referral - specialist evaluation is essential for trigger identification, diagnostic testing, and prevention strategies 1, 2