From the Guidelines
Patients who have been treated for acute anaphylaxis should be discharged home with an epinephrine auto-injector, typically prescribed as a two-pack with a standard adult dose of 0.3mg for adults or 0.15mg for children weighing less than 30kg, as well as a short course of oral antihistamines and oral corticosteroids to manage residual symptoms and prevent biphasic reactions. The most recent and highest quality study, published in 2020, emphasizes the importance of prompt administration of epinephrine in the treatment of anaphylaxis 1. According to this study, epinephrine should be administered as the first-line pharmacotherapy for uniphasic and/or biphasic anaphylaxis, and its administration should not be delayed, as this may be associated with higher morbidity and mortality.
Medications Recommended for Discharge
- Epinephrine auto-injector (such as EpiPen or Auvi-Q), typically prescribed as a two-pack with a standard adult dose of 0.3mg for adults or 0.15mg for children weighing less than 30kg
- Oral antihistamines, such as diphenhydramine (Benadryl) 25-50mg every 6 hours or cetirizine (Zyrtec) 10mg daily for 3-5 days, to manage residual symptoms
- Oral corticosteroids, such as prednisone 40-60mg daily for 3-5 days, to prevent biphasic reactions
Importance of Patient Education
Patients should receive clear instructions on when and how to use the epinephrine auto-injector, specifically to inject it into the outer thigh at the first sign of recurrent anaphylaxis and to seek immediate medical attention afterward. This medication regimen is crucial because anaphylaxis can recur within 72 hours of the initial reaction (biphasic anaphylaxis), and prompt administration of epinephrine can be life-saving. The antihistamines help control cutaneous symptoms like hives and itching, while corticosteroids reduce inflammation and help prevent delayed reactions, as recommended by previous studies 1. However, the most recent study 1 takes precedence in guiding clinical practice.
From the FDA Drug Label
1 INDICATIONS & USAGE Adrenalin® is available as a single-use 1 mL vial and a multiple-use 30 mL vial for intramuscular and subcutaneous use. Emergency treatment of allergic reactions (Type I), including anaphylaxis, which may result from allergic reactions to insect stings, biting insects, foods, drugs, sera, diagnostic testing substances and other allergens, as well as idiopathic anaphylaxis or exercise-induced anaphylaxis.
The FDA drug label does not answer the question.
From the Research
Medications Recommended for Discharge after Treating Acute Anaphylaxis
- Epinephrine auto-injector: Patients should be discharged with a prescription for an epinephrine auto-injector, as recommended by current guidelines 2, 3.
- Written instructions: Patients should receive written instructions regarding long-term management and a referral for follow-up, preferably with an allergist 2.
- Adjunct medications: Although not explicitly recommended for discharge, adjunct medications such as histamine H1 and H2 antagonists, corticosteroids, beta2 agonists, and glucagon may be considered after epinephrine administration 4.
- Glucocorticoids and H1 antagonists: These medications are weakly recommended as second-line treatments, although the evidence supporting their use is of low quality 5.
Discharge Instructions and Follow-up
- Observation period: The length of observation in the emergency department (ED) should depend on the patient's clinical course, risk factors, and social support 3.
- Patient education: Patients should receive education on the signs and symptoms of anaphylaxis, avoiding triggers, and the appropriate use of an epinephrine auto-injector 2, 3.
- Follow-up: Patients should follow up with an allergy specialist to confirm triggers and receive immunotherapy as indicated 3.