Take-Home Medications for Anaphylaxis
All patients who have experienced anaphylaxis must be discharged with two epinephrine autoinjectors (0.15 mg for 10-25 kg; 0.3 mg for ≥25 kg), along with a written anaphylaxis emergency action plan. 1
Essential Take-Home Medication: Epinephrine Autoinjectors
Epinephrine is the only first-line medication for anaphylaxis and must be prescribed as an autoinjector for community use. 1, 2
Who Should Receive Epinephrine Autoinjectors
Prescribe epinephrine autoinjectors for patients with: 1
- Previous systemic allergic reaction or anaphylaxis episode
- Food allergy combined with asthma (especially poorly controlled asthma, which significantly increases fatality risk)
- Known allergy to peanuts, tree nuts, fish, or crustacean shellfish (these cause the majority of fatal anaphylaxis)
- Consider prescribing for all patients with IgE-mediated food allergies, even without prior anaphylaxis
Dosing Specifications
Weight-based autoinjector selection: 1, 2, 3
- 0.15 mg dose: For patients weighing 10-25 kg (22-55 lbs)
- 0.3 mg dose: For patients weighing ≥25 kg (≥55 lbs)
- 0.1 mg dose: For infants >7.5 kg where available (not widely available in US/Canada) 3, 4
Critical prescribing detail: Always prescribe TWO autoinjectors, as a second dose may be needed 5-15 minutes after the first if symptoms persist or recur. 1, 2
Why Autoinjectors Over Vials/Syringes
Epinephrine autoinjectors are strongly preferred for community settings because they ensure: 1
- Ease of use by laypersons under high stress
- Accurate dosing without calculation errors
- Rapid administration without preparation time
Adjunctive Medications (NOT Substitutes for Epinephrine)
H1-Antihistamines
Oral H1-antihistamines (diphenhydramine or second-generation antihistamines) may be considered as adjunctive therapy ONLY, but should never delay or replace epinephrine. 1, 5, 3
- Diphenhydramine can be prescribed for home use at 1-2 mg/kg per dose (maximum 50 mg) 1
- Critical pitfall: Antihistamines treat only cutaneous symptoms and do NOT prevent or reverse cardiovascular collapse or airway obstruction 1, 2
Bronchodilators
Albuterol inhalers may be prescribed for patients with concurrent asthma, but only as adjunctive therapy after epinephrine. 1
- Albuterol provides bronchodilation but does not address the systemic vascular collapse of anaphylaxis 1
- Never substitute asthma inhalers for epinephrine as initial treatment 1, 2
Essential Non-Medication Components of Discharge
Beyond medications, patients must receive: 1
Written, personalized anaphylaxis emergency action plan that includes:
Plan for monitoring autoinjector expiration dates (epinephrine degrades over time, reducing efficacy) 1
Referral for allergist evaluation to identify triggers and assess ongoing risk 1, 2
Medical identification jewelry or wallet card stating "anaphylaxis" and listing triggers 1
Education on proper autoinjector technique with hands-on demonstration, as many patients fail to use devices correctly despite training 6
Critical Safety Points
Delayed epinephrine administration is directly associated with anaphylaxis fatalities. 1 Patients and caregivers must understand:
- Inject epinephrine FIRST at the earliest sign of anaphylaxis, before calling 911 or taking other medications 2, 3
- Inject into the anterolateral thigh (mid-outer thigh), NOT the deltoid or subcutaneous tissue, as intramuscular thigh injection achieves faster and higher plasma levels 3, 7
- Always seek emergency care after using epinephrine, even if symptoms improve, due to risk of biphasic reactions (symptom recurrence hours later) 1, 2
- Carry both autoinjectors at all times, as accidental allergen exposure is unpredictable 1, 6
Common pitfall: Patients often fail to carry their autoinjectors or know how to use them correctly. 6 Reinforce at every visit that the autoinjector must be immediately accessible, and periodically reassess technique.