What is the recommended epinephrine (Epi) dosing for pediatric patients experiencing anaphylaxis compared to other medical inductions, such as cardiac arrest?

Epinephrine Dosing for Pediatric Anaphylaxis

For anaphylaxis in children, administer intramuscular epinephrine 0.01 mg/kg (1:1000 solution, maximum 0.3 mg for children <30 kg, maximum 0.5 mg for children ≥30 kg) into the anterolateral thigh immediately upon recognition—this is fundamentally different from cardiac arrest dosing, which uses 0.01 mg/kg of 1:10,000 solution (10-fold more dilute) intravenously. 1, 2

Critical Distinction: Anaphylaxis vs Cardiac Arrest Dosing

Anaphylaxis (First-Line Treatment)

• Route: Intramuscular into the lateral thigh (vastus lateralis) 3, 1
• Concentration: 1:1000 (1 mg/mL) 1, 2
• Dose: 0.01 mg/kg per injection 1, 2
  • Children <30 kg: Maximum 0.3 mg (0.3 mL) per dose 1
  • Children ≥30 kg: Maximum 0.5 mg (0.5 mL) per dose 1
• Repeat interval: Every 5-15 minutes as needed 3, 2, 1
• Peak plasma concentration: Achieved in 8 ± 2 minutes 3, 4

Cardiac Arrest (Including Anaphylaxis-Induced Arrest)

• Route: Intravenous or intraosseous 3
• Concentration: 1:10,000 (0.1 mg/mL) 3
• Dose: 0.01 mg/kg (0.1 mL/kg of 1:10,000 solution) 3
• Standard resuscitative measures take priority 3

Autoinjector Dosing by Weight

The fixed-dose autoinjectors create dosing challenges across the pediatric weight spectrum, forcing clinicians to balance underdosing versus overdosing risks 3:

Weight-Based Autoinjector Selection

• 10-15 kg (22-33 lbs): 0.15 mg autoinjector provides optimal to slight overdose 3
• 15-25 kg (33-55 lbs): 0.15 mg autoinjector (may underdose at higher weights) 3
• 25-30 kg (55-66 lbs): Switch to 0.30 mg autoinjector—a 1.2-fold overdose is safer than 1.7-fold underdose 3
• ≥30 kg (≥66 lbs): 0.30 mg autoinjector provides optimal dose 3

Infants <10 kg (<22 lbs)

• The 0.15 mg autoinjector delivers >1.5-fold overdose in this weight range 3
• Despite manufacturer warnings, most pediatricians prescribe the 0.15 mg autoinjector rather than ampule/syringe/needle 3, 2
• Ampule/syringe/needle technique carries 40-fold variation in dosing accuracy and significant delays 2, 5
• The certainty of autoinjector delivery outweighs theoretical overdosing concerns in otherwise healthy infants 3

Intravenous Epinephrine for Refractory Anaphylaxis

Reserve IV epinephrine exclusively for cardiac arrest or profound hypotension unresponsive to multiple IM doses and aggressive fluid resuscitation 2, 5:

• Dose: 0.01 mg/kg of 1:10,000 solution (maximum 0.3 mg) given slowly over several minutes 2
• Alternative dosing for shock: 0.05-0.1 mg (50-100 mcg) IV bolus 3
• Continuous infusion: 0.05-0.1 mcg/kg/min, titrated to effect 3, 2
• Mandatory monitoring: Continuous ECG, blood pressure every minute, heart rate 2
• Risk profile: Significant risk of dilution and dosing errors; should only be used in hospital settings 2, 5

Pharmacokinetic Superiority of Intramuscular Route

The intramuscular route in the lateral thigh demonstrates clear pharmacokinetic advantages over subcutaneous administration 3, 4:

• IM peak time: 8 ± 2 minutes 3, 4
• Subcutaneous peak time: 34 ± 14 minutes (range 5-120 minutes) 3, 4
• Only 2 of 9 children achieved peak concentrations by 5 minutes with subcutaneous injection 4
• 6 of 8 children achieved peak concentrations by 5 minutes with IM injection 4

Management Algorithm for Escalating Anaphylaxis

Initial Treatment (0-5 minutes)

• Administer IM epinephrine 0.01 mg/kg immediately 2, 5
• Position supine with legs elevated (unless respiratory distress present) 5
• Establish IV access, provide oxygen, monitor vital signs 2, 5

Persistent Symptoms (5-15 minutes)

• Repeat IM epinephrine 0.01 mg/kg 2, 1
• Administer crystalloid bolus: 20-30 mL/kg for severe reactions 2

Refractory Anaphylaxis (>10 minutes, inadequate response)

• Double the epinephrine bolus dose 2
• Consider IV epinephrine 20-100 mcg for severe hypotension 2
• Start epinephrine infusion (0.05-0.1 mcg/kg/min) after three boluses 2
• Add norepinephrine infusion (0.05-0.5 mcg/kg/min) for persistent hypotension 2

Special Populations

• Beta-blocker patients: Administer IV glucagon 1-2 mg for refractory symptoms 2
• Patients with asthma: Higher risk for fatal anaphylaxis; consider earlier escalation to higher autoinjector dose 3

Critical Pitfalls to Avoid

• Never delay epinephrine for antihistamines or corticosteroids—delayed administration is directly associated with fatalities 2, 6, 5
• Never substitute H1 antihistamines (diphenhydramine) for epinephrine—they have slow onset (≥1 hour) and do not relieve respiratory symptoms or shock 2, 6
• Never use subcutaneous route—absorption is unpredictable and dangerously delayed 3, 4
• Never use inhaled epinephrine as substitute for injection—children cannot inhale sufficient doses to achieve therapeutic plasma concentrations 7
• Do not administer repeated injections at same site—resulting vasoconstriction may cause tissue necrosis 1
• Avoid premature discharge—observe minimum 6 hours in monitored area for biphasic reactions 2, 5

Adjunctive Therapies (Never First-Line)

• H1 antihistamines: Adjunctive only for cutaneous symptoms after epinephrine; do not relieve life-threatening manifestations 2, 6, 5
• Inhaled albuterol: May help wheezing in patients with preexisting asthma; does not treat upper airway edema or shock 2, 5
• Corticosteroids: Consider for patients with history of severe/prolonged reactions to potentially prevent biphasic reactions 2

Post-Anaphylaxis Management

• Prescribe two epinephrine autoinjectors before discharge 2, 5
• Provide written personalized emergency action plan 2
• Train patient/family on autoinjector use and anaphylaxis recognition 2
• Arrange allergist referral for trigger identification 2
• Obtain mast cell tryptase at 1 hour, 2-4 hours, and baseline (>24 hours post-reaction) 2