What is the recommended epinephrine dose and administration route for anaphylaxis in children and adults?

Epinephrine Dosing in Anaphylaxis

Administer intramuscular epinephrine immediately at 0.01 mg/kg of 1:1000 concentration (maximum 0.5 mg in adults, 0.3 mg in prepubertal children) into the anterolateral thigh, and repeat every 5-15 minutes as needed until symptoms resolve. 1, 2

Specific Dosing by Weight

Adults and Adolescents

• ≥50 kg (110 lbs): 0.3-0.5 mg intramuscularly 3, 4
• Maximum single dose: 0.5 mg 3, 4, 5
• Standard adult dose: 0.3-0.5 mL of 1:1000 (1 mg/mL) solution 3, 6

Pediatric Patients

• Weight-based dosing: 0.01 mg/kg (0.01 mL/kg of 1:1000 solution) 3, 4
• Prepubertal children maximum: 0.3 mg 3
• Children <30 kg: Up to 0.3 mg per dose 4

Autoinjector Dosing

• ≥25 kg (55 lbs): 0.3 mg EpiPen 1, 2
• 10-25 kg: 0.15 mg EpiPen Jr 1, 2
• Infants 7.5-15 kg: 0.15 mg (or 0.1 mg where available) 2, 7

Administration Technique

Injection Site

The mid-outer thigh (vastus lateralis muscle) is the only acceptable site for first-line treatment. 3, 1, 7

• Peak plasma concentration: 8±2 minutes with intramuscular thigh injection 3, 1, 7
• Subcutaneous deltoid: 34±14 minutes (unacceptably slow) 3, 1, 7
• Never inject into: Buttocks, digits, hands, or feet 4
• Can inject through clothing if necessary—do not delay for clothing removal 1

Repeat Dosing Protocol

• Interval: Every 5-15 minutes as needed 3, 1, 2, 5
• Frequency: 10-28% of patients require a second dose 1, 7
• No arbitrary maximum: Continue dosing based on clinical response 1
• The 5-minute interval can be shortened if the clinical situation demands more frequent injections 3, 1

Concurrent Emergency Measures

Immediate Actions (While Administering Epinephrine)

• Call 911/EMS immediately—do not wait to see if epinephrine works 1, 2
• Position patient supine with legs elevated (unless respiratory distress or vomiting present) 3, 1, 2
• Never allow standing, walking, or running—upright positioning increases mortality risk 3, 1
• Administer supplemental oxygen at 6-8 L/min 3, 1, 2

Fluid Resuscitation

• Adults: 1000-2000 mL normal saline bolus (5-10 mL/kg in first 5 minutes) 3, 1, 2
• Children: Up to 30 mL/kg in the first hour 3, 1, 2
• Large volumes may be necessary—some patients require 1-2 L rapidly 3, 1

Refractory Anaphylaxis (Failure of IM Epinephrine)

Transition to IV Epinephrine

If the patient fails to respond after 2-3 intramuscular doses, transition to intravenous epinephrine. 1, 2

IV Bolus Dosing

• Adults: 50-100 µg (0.05-0.1 mg) of 1:10,000 concentration IV slowly 1, 2
• Children: 1 µg/kg IV bolus 2
• Repeat: Every 5-15 minutes as needed 1, 2
• Critical safety: Use only 1:10,000 concentration (0.1 mg/mL) for IV administration—using 1:1000 can cause fatal arrhythmias 1, 2

IV Infusion Protocol

• Preparation: Add 1 mg (1 mL) of 1:1000 epinephrine to 250 mL D5W = 4.0 µg/mL 1
• Starting rate: 0.05-0.1 µg/kg/min (1-4 µg/min in adults) 1, 2
• Maximum rate: 10 µg/min 1, 2
• Requires: Continuous cardiac monitoring 1, 2

Alternative Vasopressors

For persistent hypotension despite epinephrine and fluids, add norepinephrine, vasopressin, phenylephrine, or dopamine. 1, 2

Special Populations

• Patients on β-blockers: Glucagon 1-2 mg IV (20-30 µg/kg in children, max 1 mg), followed by infusion of 5-15 µg/min 1, 2

Adjunctive Therapies (Secondary to Epinephrine)

These medications are second-line only and must never delay or replace epinephrine. 1, 2, 7

• H1 antihistamine: Diphenhydramine 25-50 mg IV/IM (1-2 mg/kg in children) for urticaria only 3, 1, 2
• H2 antihistamine: Ranitidine 50 mg IV or famotidine 20 mg IV 1, 2
• Bronchodilator: Albuterol 2.5-5 mg nebulized for persistent bronchospasm after epinephrine 1, 2
• Corticosteroids: Not recommended for acute treatment—onset 4-6 hours, no proven benefit in preventing biphasic reactions 1, 2, 5

Post-Treatment Management

Observation Requirements

• Minimum observation: 4-6 hours after complete symptom resolution 1, 2
• Extended observation (≥6 hours) or admission required for:
  • Patients who received >1 epinephrine dose 1, 2
  • Severe initial presentation with hypotension or respiratory compromise 1, 2
  • Wide pulse pressure at presentation 1, 2
  • Unknown trigger 1, 2
  • Coexisting poorly controlled asthma 1, 2

Biphasic Reaction Risk

• Incidence: 1-20% of cases (mean recurrence at 11 hours, can occur up to 72 hours) 1, 2, 5
• Strongest predictor: Requirement for multiple epinephrine doses 1, 2

Discharge Requirements

• Two epinephrine autoinjectors (appropriate dose for weight) 1, 2
• Written anaphylaxis emergency action plan detailing symptoms, triggers, and epinephrine use 3, 1, 2
• Hands-on training in autoinjector use 1, 2
• Referral to allergist within 1-2 weeks 1, 2

Critical Safety Points

No Absolute Contraindications

There is no absolute contraindication to epinephrine use in anaphylaxis—even in elderly patients with cardiovascular disease, the risk of death from untreated anaphylaxis far exceeds any epinephrine-related risk. 1, 2, 7

Common Fatal Errors to Avoid

• Delayed epinephrine administration is directly associated with anaphylaxis fatalities 1, 2, 8
• Never substitute antihistamines for epinephrine—antihistamines treat only cutaneous symptoms and do not prevent cardiovascular collapse or airway obstruction 1, 2, 7
• Do not use subcutaneous route—absorption is too slow 7, 8
• Avoid IV epinephrine as first-line—reserve for refractory cases in monitored settings due to risk of fatal arrhythmias 1, 7