What are the emergency treatment steps and medications for anaphylaxis?

Emergency Management of Anaphylaxis

Immediately inject epinephrine 0.3-0.5 mg intramuscularly into the mid-outer thigh (vastus lateralis) as soon as anaphylaxis is recognized—this is the only first-line, life-saving treatment. 1, 2

Immediate First-Line Treatment: Epinephrine

Epinephrine is the ONLY first-line medication for anaphylaxis—there are no absolute contraindications to its use, even in high-risk patients with cardiac disease. 3

Dosing and Administration

• Adults and children ≥30 kg: 0.3-0.5 mg IM (0.3-0.5 mL of 1:1000 solution) 4
• Children <30 kg: 0.01 mg/kg IM (0.01 mL/kg of 1:1000 solution), maximum 0.3 mg 4
• Route: Intramuscular injection into the anterolateral aspect of the mid-thigh (vastus lateralis muscle)—this provides superior pharmacokinetics compared to subcutaneous administration 1, 3
• Repeat dosing: Can be repeated every 5-15 minutes as needed if symptoms persist or progress 1, 2
• Frequency: 6-19% of pediatric patients require a second dose; a third dose is rarely needed 1

Critical Positioning

• Place patient supine (on their back) with legs elevated 1, 2
• If respiratory distress or vomiting: Position of comfort is acceptable 1
• Never allow the patient to stand, walk, or run—sudden postural changes can precipitate cardiovascular collapse 1

Second-Line Adjunctive Treatments

These medications are adjuncts only and should NEVER be given before or instead of epinephrine. 1, 3

H1 Antihistamines

• Diphenhydramine 25-50 mg IV/IM (or 1-2 mg/kg in children) 1, 2
• Useful for cutaneous symptoms but does not treat life-threatening manifestations 3

H2 Antihistamines

• Ranitidine 50 mg IV in adults (1 mg/kg in children), diluted in D5W and given over 5 minutes 1, 2
• Combination of H1 + H2 antihistamines is superior to H1 alone 1

Bronchodilators

• Nebulized albuterol 2.5-5 mg in 3 mL saline for bronchospasm resistant to epinephrine, repeat as necessary 1, 2

Corticosteroids

• Methylprednisolone 1-2 mg/kg/day IV every 6 hours (or equivalent) 1, 2
• Consider for patients with history of idiopathic anaphylaxis, asthma, or severe/prolonged reactions 1, 2
• Not helpful acutely but may prevent biphasic or protracted anaphylaxis 1

Fluid Resuscitation

• Establish IV access immediately 2
• Aggressive crystalloid volume replacement for hypotension or shock 1, 2

Management of Refractory Anaphylaxis

When Standard IM Epinephrine Fails

For hypotension refractory to multiple IM epinephrine doses and volume replacement, escalate to IV epinephrine or continuous infusion. 1, 2

IV Epinephrine Bolus

• 0.05-0.1 mg IV (1:10,000 solution) given slowly 2
• Only use IV epinephrine in profoundly hypotensive patients who have failed multiple IM doses and volume replacement 1
• Requires continuous hemodynamic monitoring (blood pressure every minute, ECG monitoring) 1

Epinephrine Infusion

• Preparation: Add 1 mg (1 mL) of 1:1000 epinephrine to 250 mL D5W (concentration 4.0 μg/mL) 2
• Dosing: Start at 1-4 μg/min, titrate up to maximum 10 μg/min as needed 2
• Alternative: 0.05-0.1 μg/kg/min infusion when >3 epinephrine boluses have been given 3

Vasopressor Support

• Dopamine 400 mg in 500 mL D5W at 2-20 μg/kg/min for persistent hypotension despite epinephrine and fluids 1, 2
• Titrate to maintain adequate blood pressure with continuous hemodynamic monitoring 1

Beta-Blocker Complication

• Glucagon 1-5 mg IV over 5 minutes (20-30 μg/kg in children, max 1 mg), followed by infusion of 5-15 μg/min 1, 2
• Use when beta-blocker therapy complicates treatment response 1
• Aspiration precautions required—glucagon causes nausea and vomiting 1

Cardiac Arrest Management

If cardiac arrest occurs during anaphylaxis, prolonged resuscitation efforts are strongly encouraged—outcomes are better than typical cardiac arrest because patients are often young with healthy cardiovascular systems. 1, 2

High-Dose IV Epinephrine Protocol

• Initial: 1-3 mg IV (1:10,000) slowly over 3 minutes 1, 2
• Second dose: 3-5 mg IV over 3 minutes 1, 2
• Continuous infusion: 4-10 mg/min (or up to 10 μg/min) 1, 2
• Pediatric dosing: 0.01 mg/kg (0.1 mL/kg of 1:10,000 solution, max 0.3 mg) every 3-5 minutes 1
• For refractory arrest: Consider higher doses of 0.1-0.2 mg/kg (0.1 mL/kg of 1:1000 solution) for unresponsive asystole or pulseless electrical activity 1

Additional Cardiac Arrest Interventions

• Standard BLS/ACLS protocols 2
• Rapid, aggressive volume expansion is mandatory 1, 2
• Atropine and transcutaneous pacing for asystole or pulseless electrical activity 1, 2

Observation and Monitoring

• Minimum observation period: 6 hours in a monitored area, or until stable with regressing symptoms 3
• Individualize observation time based on severity, distance to emergency facility, and risk of biphasic reaction 1
• Continuous vital sign monitoring, especially in patients with shock 2
• Supplemental oxygen as needed 2

Mast Cell Tryptase Sampling

• First sample: 1 hour after reaction onset 3
• Second sample: 2-4 hours after onset 3
• Baseline sample: At least 24 hours post-reaction 3

Critical Pitfalls to Avoid

Most Dangerous Errors

• Using antihistamines or corticosteroids as first-line treatment instead of epinephrine—this is the most common fatal error 2, 3
• Delaying epinephrine administration—failure to inject promptly is associated with fatal outcomes 1
• Administering epinephrine subcutaneously instead of IM—delayed onset of action 3
• Giving IV epinephrine in non-arrest situations without monitoring—risk of severe adverse effects 1

Other Important Pitfalls

• Injecting into buttocks, digits, hands, or feet—avoid these sites 4
• Allowing patient to stand or walk—can precipitate cardiovascular collapse 1
• Discharging too early without adequate observation—biphasic reactions can occur 2
• Failing to prescribe epinephrine autoinjector and provide education—essential for future episodes 2

High-Risk Patient Considerations

Fatal anaphylaxis is strongly associated with:

• Adolescence 1
• Concomitant asthma, especially if severe or poorly controlled 1
• Delayed or absent epinephrine administration 1
• Patients on beta-blockers (may require glucagon) 1

There are no absolute contraindications to epinephrine use in anaphylaxis, even in elderly patients with cardiac disease, complex congenital heart disease, or pulmonary hypertension. 3