Epinephrine Dosing for Anaphylaxis
Administer intramuscular epinephrine 0.01 mg/kg of 1:1000 solution (maximum 0.5 mg in adults, 0.3 mg in children) into the anterolateral thigh immediately upon recognition of anaphylaxis. 1, 2, 3
Specific Dosing by Weight
Adults and Adolescents
- Adults ≥30 kg: 0.3-0.5 mg (0.3-0.5 mL of 1:1000 solution) intramuscularly 3
- Adults ≥45 kg: Consider the 0.5 mg dose based on shared decision-making, as the 0.3 mg dose results in progressive underdosing as weight increases above 30 kg 4
Pediatric Dosing
- Children <30 kg: 0.01 mg/kg (0.01 mL/kg of 1:1000 solution), maximum 0.3 mg 3
- Children 10-25 kg: 0.15 mg autoinjector dose 1
- Children ≥25 kg: 0.3 mg autoinjector dose 1
- Infants <7.5 kg: The 0.15 mg autoinjector is still preferable to ampule/syringe methods despite theoretical overdosing concerns, as manual dosing carries 40-fold variation in accuracy and significant delays 2
Administration Technique
Inject at a 90-degree angle into the mid-outer anterolateral thigh (vastus lateralis muscle) to ensure intramuscular rather than subcutaneous delivery 1, 2. This site achieves peak plasma concentrations in 8±2 minutes compared to 34±14 minutes with subcutaneous injection 1, 5. The injection can be administered through clothing if necessary during emergencies, as delay is associated with increased mortality 1.
Repeat Dosing
Repeat the same dose every 5-15 minutes if symptoms persist or recur 6, 1, 2. Both UK and international consensus guidelines support repeating epinephrine every 5 minutes as clinically needed 6. The interval can be liberalized for more frequent injections if deemed appropriate 6.
Intravenous Epinephrine for Refractory Cases
For severe, refractory anaphylaxis unresponsive to multiple intramuscular doses:
Adults
- Initial infusion: Add 1 mg (1 mL of 1:1000) to 250 mL D5W, yielding 4 μg/mL concentration 6, 2
- Infusion rate: 1-4 μg/min (15-60 drops/min with microdrop apparatus), titrating up to maximum 10 μg/min 6, 2
- Alternative protocol: 1:100,000 solution (1 mg in 100 mL saline) at 30-100 mL/h (5-15 μg/min), titrated based on clinical response 6
Children
- Bolus dosing: 0.01 mg/kg (0.1 mL/kg of 1:10,000 solution; maximum 0.3 mg) given slowly over several minutes 2
- Continuous infusion: 0.05-0.1 μg/kg/min when more than three boluses have been administered 2
- "Rule of 6" alternative: 0.6 × body weight (kg) = mg diluted to 100 mL saline; then 1 mL/h delivers 0.1 μg/kg/min 6
Continuous hemodynamic monitoring is mandatory when administering IV epinephrine, including continuous ECG, blood pressure every minute, and heart rate monitoring 2. However, IV epinephrine should not be withheld in scenarios where monitoring is unavailable if deemed essential after failure of several intramuscular doses 6.
Critical Pitfalls to Avoid
- Never delay epinephrine to give antihistamines or corticosteroids first—delayed administration is directly associated with anaphylaxis fatalities 1, 5, 7, 8
- Avoid subcutaneous injection, which delays absorption by approximately 26 minutes compared to intramuscular 1, 5
- Do not inject into the deltoid muscle—the anterolateral thigh provides superior and more consistent absorption 1
- Avoid ampule/syringe/needle for home use due to 40-fold dosing variation and significant delays 2, 9
- There are no absolute contraindications to epinephrine in anaphylaxis, even in patients with cardiac disease, advanced age, or frailty—the benefits always outweigh risks 1, 5
Special Populations
Patients on beta-blockers may be unresponsive to epinephrine and require IV glucagon 1-2 mg 2. For persistent hypotension despite epinephrine and fluids, add norepinephrine infusion (0.05-0.5 μg/kg/min) or consider vasopressin 1-2 IU bolus 2.