What is the treatment for anaphylaxis?

Treatment of Anaphylaxis

Epinephrine is the first-line treatment for anaphylaxis and should be administered promptly at the onset of symptoms, as it is the most important therapeutic agent for managing this life-threatening condition. 1, 2

Immediate Management

• Administer intramuscular epinephrine 1:1000 (1 mg/mL) at a dose of 0.01 mg/kg with a maximum single dose of 0.5 mg (for patients >50 kg) into the vastus lateralis (anterolateral thigh) for optimal absorption 1, 2
• Place patient in recumbent position with lower extremities elevated to prevent orthostatic hypotension and help shunt circulation from the periphery to vital organs 1, 2
• Establish and maintain airway; ventilatory assistance may be necessary 1
• Administer oxygen to patients with prolonged reactions, pre-existing hypoxemia, myocardial dysfunction, or those requiring multiple doses of epinephrine 1
• Establish intravenous access for fluid replacement with normal saline 1, 2

Fluid Resuscitation

• Administer 1-2 L of normal saline to adults at a rate of 5-10 mL/kg in the first 5 minutes 1
• For children, administer up to 30 mL/kg in the first hour 1
• Monitor patients with congestive heart failure or chronic renal disease carefully to prevent volume overload 1

For Refractory Anaphylaxis

• For cases not responding to intramuscular epinephrine and volume resuscitation, consider intravenous epinephrine 1
• Aqueous epinephrine 1:1000,0.1-0.3 mL in 10 mL of normal saline, can be administered intravenously over several minutes 1
• Alternatively, prepare an epinephrine infusion by adding 1 mg of 1:1000 epinephrine to 250 mL of D5W (concentration 4.0 μg/mL) and infuse at 1-4 μg/min, increasing to maximum of 10.0 μg/min if needed 1

Second-Line Treatments

• Administer antihistamines (H1 and H2 antagonists) as second-line agents after epinephrine 1, 2
• Consider nebulized albuterol 2.5-5 mg in 3 mL saline for bronchospasm resistant to epinephrine 2, 3
• Consider glucagon 1-5 mg IV if the patient is on beta-blockers, as it can help relax bronchial smooth muscle independent of beta-blockade 2, 3
• Corticosteroids are not helpful for acute management but may be considered to prevent protracted or biphasic anaphylaxis 1, 2

Post-Acute Management

• Observe patients for at least 4-12 hours after symptom resolution due to risk of biphasic reactions 1, 4, 5
• Refer patients to an allergist for comprehensive evaluation and identification of triggers 2, 5
• Prescribe self-injectable epinephrine and educate on proper use 2, 5
• Advise patients to wear medical identification (e.g., Medic Alert jewelry) 1, 2

Common Pitfalls to Avoid

• Delaying epinephrine administration - this is associated with increased mortality and risk of biphasic reactions 1, 2
• Using antihistamines or corticosteroids as first-line treatment instead of epinephrine 1, 2
• Failing to place patient in recumbent position, which may worsen hypotension 1, 2
• Inadequate fluid resuscitation in hypotensive patients 1, 2
• Failing to recognize anaphylaxis when cutaneous symptoms are absent (occurs in up to 20% of cases) 4

Special Considerations

• No absolute contraindications exist for using epinephrine to treat anaphylaxis, even in patients with cardiac disease, advanced age, or frailty 1
• For patients on beta-blockers with severe anaphylaxis, higher doses of epinephrine may be needed, and glucagon should be considered 2
• Biphasic reactions can occur up to 72 hours later (mean 11 hours), with early epinephrine administration potentially reducing this risk 1
• The FDA-approved indication for epinephrine includes emergency treatment of allergic reactions (Type I), including anaphylaxis from various triggers 6