What is the initial treatment for a patient with pruritus (itching) of the mouth, mild wheeze, and urticaria (hives) on the chest after eating, with no signs of respiratory distress, oropharyngeal swelling, or abnormal vital signs?

Initial Treatment: Administer Intramuscular Epinephrine Immediately

This patient meets criteria for anaphylaxis and requires immediate intramuscular epinephrine 0.3-0.5 mg in the mid-outer thigh, even with normal vital signs and no oropharyngeal swelling. 1

Why This is Anaphylaxis

This presentation fulfills diagnostic criteria for anaphylaxis because the patient has:

• Acute onset after food exposure (eating lunch) 1
• Multi-system involvement: skin symptoms (itchy mouth, hives on chest) PLUS respiratory symptoms (wheeze) 1

The absence of distress, normal vital signs, and lack of oropharyngeal swelling does NOT exclude anaphylaxis. 1 Anaphylaxis can present with varying severity, and respiratory involvement (wheeze) combined with cutaneous symptoms after allergen exposure mandates epinephrine treatment. 1

Immediate Management Algorithm

Step 1: Inject epinephrine 0.3-0.5 mg IM in the mid-outer thigh immediately 1

• This is the single most important intervention and can be life-saving 1
• The dose for a teenager/adult is up to 0.5 mg 1
• Prepare for a second dose 5-15 minutes later if response is inadequate (6-19% of patients require a second dose) 1

Step 2: Position the patient appropriately 1

• Place supine or in position of comfort if respiratory distress worsens 1
• Elevate lower extremities to increase venous return 2
• Do NOT allow standing, walking, or running 1

Step 3: Call for emergency transport (911/EMS) 1

• Transport to emergency department for monitoring, even if symptoms improve 1

Adjunctive Treatments (Secondary to Epinephrine)

After epinephrine administration, consider:

H1 antihistamines for symptomatic relief of itching and hives:

• Diphenhydramine 25-50 mg OR cetirizine 10 mg 2
• These do NOT treat bronchospasm or prevent progression—they are adjunctive only 3
• Critical pitfall: Never substitute antihistamines for epinephrine in anaphylaxis 3

Bronchodilator therapy for persistent wheeze:

• If wheeze persists after epinephrine, consider ipratropium bromide via nebulizer 3
• Ipratropium provides additive benefit in moderate-severe bronchospasm 3
• Do not use albuterol as first-line for anaphylaxis-related bronchospasm—epinephrine is the primary treatment 1

IV fluid bolus if hypotension develops:

• Ringer's lactate 10-20 mL/kg if signs of hypotension or significant vomiting emerge 2

Monitoring Requirements

• Monitor vital signs every 15 minutes until symptoms resolve 2
• Continue monitoring for at least 2-4 hours after symptom resolution 2
• Consider extended observation up to 24 hours due to risk of biphasic reactions (recurrence of symptoms) 2

Common Pitfalls to Avoid

Pitfall #1: Delaying epinephrine because vital signs are normal

• Fatal anaphylaxis is associated with failure to inject epinephrine promptly 1
• Normal vital signs do not exclude anaphylaxis when multi-system symptoms are present 1

Pitfall #2: Treating with antihistamines alone

• Antihistamines do NOT relieve wheeze, stridor, or acute bronchospasm 3
• They are adjunctive only and should never replace epinephrine 3

Pitfall #3: Assuming mild presentation means no epinephrine needed

• The presence of wheeze (respiratory involvement) plus cutaneous symptoms after food exposure mandates epinephrine 1
• Symptoms can progress rapidly 1