What is the first line of treatment for a patient of any age with anaphylaxis, regardless of medical history?

Anaphylaxis Management

Intramuscular epinephrine is the first-line treatment for anaphylaxis in all patients regardless of age or medical history, and must be administered immediately upon recognition of anaphylaxis. 1, 2, 3

Immediate Epinephrine Administration

The cornerstone of anaphylaxis management is prompt intramuscular epinephrine injection into the anterolateral thigh (vastus lateralis muscle), as this route provides optimal absorption compared to subcutaneous or other routes. 1

Dosing by Weight:

• Adults and adolescents >50 kg: 0.3-0.5 mg of 1:1000 (1 mg/mL) epinephrine intramuscularly 1, 2
• Children: 0.01 mg/kg intramuscularly, with maximum single dose of 0.3 mg for prepubertal children 1
• Autoinjector dosing: 0.3 mg for patients >30 kg; 0.15 mg for children 25-30 kg; 0.1 mg formulation available for infants 1

Critical Timing Considerations:

Delayed epinephrine administration is directly associated with anaphylaxis fatalities and increased risk of biphasic reactions. 1, 4 The medication is most effective when given immediately at symptom onset, and there is widespread consensus that no other intervention should precede epinephrine. 1, 5, 6

No Absolute Contraindications

There are no absolute contraindications to epinephrine use in anaphylaxis, including cardiac disease, advanced age, frailty, or any other comorbidity. 1, 2, 4 The risk of death from untreated anaphylaxis far exceeds any theoretical risk from epinephrine administration. 2

Repeat Dosing

Epinephrine may be repeated every 5-15 minutes as needed for inadequate response or persistent symptoms. 1, 4 Approximately 6-19% of pediatric patients and 17% of all patients require a second dose. 1

Patient Positioning

Place the patient supine with lower extremities elevated immediately after epinephrine administration. 1, 2 If respiratory distress or vomiting is present, position for comfort, but never allow the patient to stand, walk, or run, as sudden postural changes can precipitate cardiovascular collapse. 1, 2

Adjunctive Treatments (Secondary Only)

These interventions should occur only after epinephrine administration, not before or instead of it: 1

• Supplemental oxygen: 6-8 L/min for respiratory symptoms 1, 2, 4
• IV fluid resuscitation: Large volumes of normal saline for hypotension or incomplete response to epinephrine 1, 4
• Albuterol: Nebulized (1.5 mL for children, 3 mL for adults) or MDI (4-8 puffs for children, 8 puffs for adults) for persistent bronchospasm 1, 2
• H1 antihistamines: Diphenhydramine 1-2 mg/kg (maximum 50 mg) - considered second-line only 1
• Glucocorticoids: Second-line therapy only, not for acute management 1

Refractory Anaphylaxis

For protracted anaphylaxis unresponsive to intramuscular epinephrine, prepare continuous IV epinephrine infusion at 1:10,000 concentration (1 mg/10 mL), starting at 2 mcg/min and titrating up to 10 mcg/min based on blood pressure, heart rate, and oxygenation. 1, 4 For patients on beta-blockers who are unresponsive to epinephrine, administer glucagon 1-5 mg IV over 5 minutes followed by infusion of 5-15 mcg/min. 4

Mandatory Observation and Transfer

All patients who receive epinephrine for anaphylaxis must be transferred to an emergency department for observation, preferably by EMS vehicle. 1, 2 Observe for a minimum of 4-6 hours after symptom resolution, as biphasic reactions can occur in up to 17% of cases. 1, 2 Prolonged observation or hospital admission is warranted for severe reactions, refractory symptoms, or delayed epinephrine administration. 1, 4

Common Pitfalls to Avoid

• Delaying epinephrine while administering antihistamines or steroids first - this is the most common fatal error 1, 6
• Subcutaneous instead of intramuscular injection - delays onset of action 5, 6
• Injection into deltoid or gluteal muscle - vastus lateralis provides superior absorption 1
• Confusing anaphylaxis with vasovagal reaction - vasovagal presents with bradycardia and lacks cutaneous manifestations (urticaria, angioedema, flushing), whereas anaphylaxis typically shows tachycardia and skin involvement 1
• Underdosing in obese patients - use actual body weight for dosing calculations 1

Discharge Requirements

Before discharge, ensure: 1, 2

• Two epinephrine autoinjectors prescribed with demonstrated proper technique 1, 2
• Written anaphylaxis emergency action plan provided 1, 2
• Referral to allergist-immunologist arranged 1, 2
• Plan for monitoring autoinjector expiration dates 1