What is the treatment for an allergic reaction to food?

Treatment for Allergic Reactions to Food

Intramuscular epinephrine is the first-line and only definitive treatment for food-induced anaphylaxis and must be administered immediately upon recognition of severe symptoms. 1, 2, 3

Immediate Management of Severe Reactions (Anaphylaxis)

Epinephrine Administration

• Inject epinephrine intramuscularly into the anterolateral thigh (vastus lateralis muscle) as the primary treatment 1, 2, 4
• Dosing:
  • Adults and children ≥30 kg: 0.3-0.5 mg of 1:1000 solution 1, 2, 4
  • Children <30 kg: 0.01 mg/kg (maximum 0.3 mg) 1, 2, 3
  • For children 10-25 kg: use 0.15 mg auto-injector 3
  • For children >25 kg: use 0.3 mg auto-injector 3
• Repeat dosing every 5-10 minutes if symptoms persist or recur 1, 4
• There are no absolute contraindications to epinephrine in anaphylaxis, even in patients with cardiovascular disease, as the risk of death from untreated anaphylaxis outweighs potential cardiac effects 1, 2

Positioning and Supportive Care

• Place patient in recumbent position with legs elevated (if tolerated and not compromising airway) 2
• Administer supplemental oxygen for hypoxia 2, 3
• Give large-volume IV fluid resuscitation (10-20 mL/kg bolus of normal saline) for persistent hypotension or incomplete response to epinephrine 1, 2, 3

Adjunctive Medications (Secondary to Epinephrine)

These medications are not substitutes for epinephrine and should only be given after or alongside epinephrine administration 1:

• Bronchodilators (albuterol): For bronchospasm—1.5 mL nebulized for children, 3 mL for adults, or 4-8 puffs via inhaler 2, 3
• H1 antihistamine (diphenhydramine): 1-2 mg/kg (maximum 50 mg) IV or oral 1, 2, 3
• H2 antihistamine (ranitidine): 1-2 mg/kg, used in combination with H1 blocker 1, 3
• Corticosteroids (prednisone or methylprednisolone): 1 mg/kg (maximum 60-80 mg) to potentially prevent biphasic reactions 1, 3

Management of Mild to Moderate Reactions

For isolated mild symptoms (flushing, urticaria, mild angioedema, oral allergy syndrome without systemic involvement):

• H1 and H2 antihistamines can be used alone 1
• Critical caveat: Maintain close observation for progression to anaphylaxis 1
• If any progression occurs or if patient has history of prior severe reaction, immediately administer epinephrine 1

Observation and Monitoring

• All patients who receive epinephrine must be transferred to an emergency facility 1
• Observe for minimum 4-6 hours after symptom resolution to monitor for biphasic reactions (which occur in up to 20% of cases) 1, 2, 3
• Prolonged observation or hospital admission is required for severe or refractory symptoms 1

Discharge Planning

Every patient must leave with:

• Two epinephrine auto-injectors (second dose needed in approximately 20% of reactions) 1, 3
• Written anaphylaxis emergency action plan 1, 3
• Training on proper auto-injector technique 1
• Plan for monitoring expiration dates 1, 3
• Medical identification jewelry or wallet card 1

Post-Discharge Medications (2-3 days)

• H1 antihistamine (diphenhydramine every 6 hours or non-sedating alternative) 1
• H2 antihistamine (ranitidine twice daily) 1
• Corticosteroid (prednisone daily) 1

Follow-Up

• Arrange appointment with primary care provider 1
• Consider referral to allergist/immunologist for comprehensive evaluation, identification of trigger foods, and long-term management 1, 3

High-Risk Populations

Patients at increased risk for severe or fatal reactions include:

• Adolescents and young adults (highest risk group for fatal reactions) 2
• Those with history of prior anaphylaxis to food 2, 5
• Patients with asthma (particularly poorly controlled) 1, 2, 5
• Allergies to peanuts, tree nuts, fish, or shellfish (more likely to cause severe reactions) 6, 5

For these high-risk patients, epinephrine should be administered at the onset of even mild symptoms 1

Common Pitfalls to Avoid

• Never delay epinephrine administration in favor of antihistamines alone—delayed treatment is associated with fatalities 1, 7
• Never inject epinephrine into buttocks, digits, hands, or feet—only use anterolateral thigh 4
• Do not rely on antihistamines or inhalers to treat severe reactions—they are adjunctive only 1
• Do not discharge patients without two auto-injectors and proper training—most fatal reactions occur in those with known allergies who lacked immediate access to epinephrine 1, 7