What is the recommended dose of epinephrine (adrenaline) for anaphylactic shock?

Epinephrine Dosing in Anaphylactic Shock

Route-Specific Dosing

For anaphylactic shock, intramuscular epinephrine 0.3-0.5 mg (1:1000 concentration) injected into the anterolateral thigh is the first-line treatment for adults, while intravenous epinephrine at 0.05-0.1 mg (1:10,000 concentration) should be reserved for patients with established IV access who have profound hypotension or cardiovascular collapse. 1, 2

Intramuscular Administration (First-Line)

• Adults: 0.3-0.5 mg of 1:1000 concentration injected into the anterolateral thigh (vastus lateralis) 3, 2, 4
• Children: 0.01 mg/kg (maximum 0.3 mg) injected into the anterolateral thigh 3, 2
• Repeat dosing: Every 5-15 minutes as needed if symptoms persist or recur 2, 4
• Autoinjector dosing for children:
  • 0.15 mg for children weighing 10-25 kg (22-55 lb) 3
  • 0.30 mg for children weighing ≥25 kg (≥55 lb) 3

The intramuscular route is preferred because it provides rapid absorption, has a favorable safety profile, and is easier to administer in emergency situations. 1, 4

Intravenous Administration (Advanced Management)

IV epinephrine should only be used when an IV line is already in place and the patient has not responded to IM epinephrine and aggressive fluid resuscitation. 1

IV Bolus Dosing

• Initial dose: 0.05-0.1 mg (50-100 mcg) of 1:10,000 concentration 3, 1, 2
• This represents 5-10% of the cardiac arrest dose 3, 1
• Administer slowly over several minutes to minimize adverse cardiovascular effects 1
• Critical safety point: Fatal overdoses have been reported with IV epinephrine, making close hemodynamic monitoring mandatory 3, 1

IV Continuous Infusion

• Infusion rate: 5-15 mcg/min, titrated to clinical response 3, 1, 2
• Preparation methods:
  • Add 1 mg (1 mL) of 1:1000 epinephrine to 250 mL D5W (concentration: 4 mcg/mL) 1
  • Add 1 mg (1 mL) of 1:1000 epinephrine to 100 mL saline (concentration: 10 mcg/mL) 1
• IV infusion allows for careful titration and may be superior to repeated boluses for maintaining hemodynamic stability 3, 1

Clinical Decision Algorithm

When to Use IM vs IV Epinephrine

Use IM epinephrine (0.3-0.5 mg) as initial therapy for ALL patients with anaphylaxis. 1, 2, 4

Consider IV epinephrine (0.05-0.1 mg bolus or 5-15 mcg/min infusion) only when:

1. IV access is already established 1
2. Patient has profound hypotension unresponsive to IV fluids and IM epinephrine 1
3. Patient has failed to respond to several doses of IM epinephrine 1
4. Patient is in cardiac arrest from anaphylaxis 3, 2

Supportive Management

Aggressive fluid resuscitation is essential alongside epinephrine:

• Adults: 1000 mL boluses of isotonic crystalloid (normal saline or Ringer's lactate) 3, 2
• Children: 20 mL/kg boluses 2
• Titrate to systolic blood pressure >90 mm Hg 3
• Anaphylactic shock can cause loss of up to 37% of circulating blood volume due to vasodilation and capillary leak 3, 5

Special Populations and Refractory Cases

Patients on Beta-Blockers

For patients taking beta-blockers who are unresponsive to epinephrine, administer glucagon: 2

• Adults: 1-5 mg IV over 5 minutes, followed by infusion of 5-15 mcg/min 2
• Children: 20-30 mcg/kg (maximum 1 mg) over 5 minutes 2
• Glucagon works through a non-adrenergic mechanism and can bypass beta-blockade 2

Refractory Hypotension

If hypotension persists despite epinephrine and fluids, consider alternative vasopressors: 1, 2

• Dopamine 2-20 mcg/kg/min 1, 2
• Vasopressin has been reported in case reports for catecholamine-resistant shock, though not in standard guidelines 6

Critical Safety Considerations and Monitoring

Mandatory Monitoring with IV Epinephrine

• Continuous hemodynamic monitoring is essential 3, 1
• In settings without advanced monitoring: every-minute blood pressure measurements, continuous pulse monitoring, and ECG if available 1

Potential Adverse Effects

• Tachyarrhythmias and ectopic beats 1
• Hypertension 1
• Risk of potentially lethal arrhythmias 1
• Myocardial ischemia from coronary vasospasm (rare but reported) 7
• Extravasation causing severe skin injury with IV administration 1

Common Pitfalls to Avoid

1. Delaying epinephrine administration: Epinephrine must be given immediately—it is the only medication that addresses both respiratory and cardiovascular collapse 4, 8
2. Using incorrect concentration: Never use 1:1000 concentration for IV administration; this can cause fatal overdose 1
3. Administering IV epinephrine too rapidly: This increases risk of adverse cardiovascular effects 1
4. Prioritizing antihistamines or corticosteroids over epinephrine: These are adjunctive therapies only and provide no acute benefit 2
5. Subcutaneous administration: This route has delayed onset and is no longer recommended 4, 9
6. Failing to repeat doses: Many patients require multiple doses of epinephrine every 5-15 minutes 2, 4
7. Inadequate fluid resuscitation: Anaphylactic shock requires aggressive volume replacement alongside epinephrine 3, 5

Observation Period

All patients should be observed for at least 6 hours after treatment or until stable and symptoms have resolved, as biphasic reactions can occur. 2