Epinephrine IM is first-line. Antihistamines and steroids are adjuncts and do NOT replace epinephrine. Call 911 for every anaphylaxis case, even if symptoms resolve after epi (biphasic risk).
Anaphylaxis emergency card
Weight-based dosing for epinephrine and common adjuncts. Enter a patient weight for calculated doses.
Repeat epi every 5–15 min if symptoms persist. No absolute contraindications in true anaphylaxis.
2. Position, airway, oxygen
Supine with legs elevated (unless respiratory distress — then sitting).
Do NOT sit up abruptly (empty ventricle / cardiac arrest risk).
High-flow O₂; prepare for airway support.
IV access; 20 mL/kg NS bolus if hypotensive.
3. Adjuncts (after epinephrine)
H1 blocker
Diphenhydramine 1–1.25 mg/kg IV/IM (max 50 mg)
H2 blocker
Famotidine 0.25–0.5 mg/kg IV (max 20 mg)
Steroid
Methylprednisolone 1–2 mg/kg IV (max 60–125 mg)
Bronchospasm: albuterol nebulizer 2.5–5 mg. Refractory hypotension: epi infusion 0.1–1 mcg/kg/min after ED transfer.
4. Observation & disposition
Observe minimum 4–6 hours after symptom resolution (biphasic reactions in 5–20%, typically within 8 h).
Prescribe TWO epinephrine auto-injectors at discharge; demonstrate use.
Refer to allergy/immunology for workup.
Anaphylaxis action plan; medical ID bracelet.
Avoid identified trigger.
Diagnostic criteria (any ONE)
Acute skin/mucosal involvement + respiratory or hypotension/end-organ.
Two or more of: skin, respiratory, hypotension, or persistent GI after likely allergen.
Hypotension after known allergen (age-appropriate BP).
For licensed clinician reference only. This content is a quick-reference aid and is not medical advice. Verify every dose, indication, contraindication, and interaction against current manufacturer labeling and authoritative guidelines (AAP, CDC, IDSA, Sanford Guide, LactMed) before prescribing. The authors and publisher accept no liability for clinical decisions made using this tool.