What is the immediate treatment for a patient experiencing anaphylaxis?

Immediate Treatment of Anaphylaxis

Administer intramuscular epinephrine 0.3-0.5 mg (adults) or 0.01 mg/kg (children, maximum 0.3-0.5 mg) into the mid-outer thigh immediately upon recognition of anaphylaxis—this is the single most critical intervention that saves lives. 1, 2

First-Line Treatment: Epinephrine Administration

Epinephrine is the only appropriate first-line medication for anaphylaxis with no absolute contraindications. 1, 2 When in doubt about whether a reaction constitutes anaphylaxis, it is better to administer epinephrine than to delay. 1

Dosing and Route

• Adults and adolescents ≥50 kg: 0.3-0.5 mg intramuscular (1:1000 concentration) 1, 2, 3
• Children <50 kg: 0.01 mg/kg intramuscular (maximum 0.3 mg for prepubertal children, 0.5 mg for larger children) 1, 2, 4
• Injection site: Mid-outer aspect of the thigh (vastus lateralis muscle)—this provides faster absorption and higher peak plasma levels compared to subcutaneous or arm injection 1, 2
• The injection can be given through clothing, but avoid seams, pockets, or other obstructions 5

Repeat Dosing

• Administer a second dose 5-15 minutes after the first if symptoms persist or worsen 1, 5, 4
• Between 7-18% of patients require more than one dose of epinephrine 1, 4
• Repeat doses every 5-15 minutes as needed until symptoms resolve or emergency medical services arrive 1, 4
• If the patient requires three or more intramuscular doses or develops refractory hypotension, consider intravenous epinephrine (50-100 mcg boluses of 1:10,000 concentration or continuous infusion at 5-15 mcg/min) 4

Immediate Concurrent Actions

Patient Positioning

• Place the patient supine (flat on back) with lower extremities elevated 2, 6
• If respiratory distress or vomiting is present, position for comfort 1, 2
• Never allow the patient to stand, walk, or run—this can precipitate sudden cardiovascular collapse and death 2, 6

Activate Emergency Medical Services

• Call 911 or activate emergency response immediately 1, 2
• Approximately 500-1000 people die annually in the United States from anaphylaxis, and patients may require advanced interventions including intubation, intravenous fluids, and vasopressors 1

Adjunctive Treatments (Only AFTER Epinephrine)

These are secondary interventions that should never delay epinephrine administration:

• Supplemental oxygen for patients with respiratory symptoms 2
• Intravenous fluid resuscitation with large volumes (crystalloids or colloids) for hypotension or incomplete response to epinephrine 1, 2
• Albuterol nebulizer for persistent bronchospasm 2
• H1 antihistamines (e.g., diphenhydramine) and H2 antihistamines (e.g., ranitidine) may provide symptomatic relief but are not life-saving 1
• Corticosteroids may help prevent biphasic reactions but have no role in acute management 1

Critical Pitfalls to Avoid

• Delayed epinephrine administration is the most common factor in anaphylaxis fatalities 4, 7, 6
• Do not substitute antihistamines or corticosteroids for epinephrine—these medications do not prevent or reverse airway obstruction or cardiovascular collapse 1
• Avoid subcutaneous administration (slower onset) or intravenous bolus in non-critical care settings (higher risk of adverse effects) 1, 7
• Accidental injection into a finger can cause vasoconstriction and necrosis—inject only into the thigh 5
• Do not delay treatment to obtain intravenous access or wait for help to arrive 2

Post-Treatment Management

Observation and Transfer

• All patients must be transferred to an emergency department, preferably by emergency medical services 5, 2
• Minimum observation period is 4-6 hours after successful treatment 2, 4
• Patients requiring multiple epinephrine doses, those with severe initial presentations, or those with unknown triggers require extended observation due to higher risk of biphasic reactions (recurrence hours later) 4

Discharge Planning

• Prescribe two epinephrine autoinjectors with hands-on training for proper use 2
• Provide a written anaphylaxis emergency action plan 2
• Refer to an allergist for trigger identification and long-term management 2
• Instruct patients to wear medical identification (e.g., MedicAlert jewelry) 1

High-Risk Populations

Patients at increased risk for severe or fatal anaphylaxis include:

• Adolescents and young adults 2
• Those with coexisting asthma 2, 6
• Previous history of anaphylaxis 2
• Peanut or tree nut allergies 2, 6
• Delayed epinephrine use in prior reactions 6

These patients require heightened vigilance and must carry epinephrine autoinjectors at all times. 2