What is the treatment for an allergic reaction in an infant?

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From the Guidelines

The most effective treatment for an allergic reaction in an infant, particularly for anaphylaxis, is the prompt administration of epinephrine via an intramuscular injection in the mid-outer thigh, which can be life-saving. For infants weighing less than 15 kg, the dosage of epinephrine is crucial, and while the lowest dose available in epinephrine autoinjectors (EAs) is 0.15 mg, this may be a high dose for many infants, especially those weighing 7.5 kg and under 1.

When considering the treatment of allergic reactions in infants, it's essential to differentiate between mild and severe reactions. For mild reactions, antihistamines like diphenhydramine can be considered, but the dosage must be carefully calculated based on the infant's weight, typically at 1.25 mg/kg every 6 hours. However, for severe allergic reactions or anaphylaxis, immediate administration of epinephrine is critical, and it should be followed by calling emergency services.

Key points in managing allergic reactions in infants include:

  • Prompt recognition and diagnosis of anaphylaxis using validated clinical criteria
  • Administration of epinephrine as soon as possible for anaphylaxis
  • Education of parents and caregivers on the recognition and management of anaphylaxis, including the use of epinephrine autoinjectors
  • Development of a personalized anaphylaxis emergency action plan for infants with a history of severe allergic reactions
  • Identification and avoidance of known allergens to prevent future reactions

Given the potential severity of allergic reactions in infants, it is crucial for parents and healthcare providers to be prepared and educated on the signs of anaphylaxis and the proper use of epinephrine autoinjectors, as highlighted in the clinical report from the American Academy of Pediatrics 1.

From the FDA Drug Label

1 INDICATIONS & USAGE Adrenalin® is available as a single-use 1 mL vial and a multiple-use 30 mL vial for intramuscular and subcutaneous use. Emergency treatment of allergic reactions (Type I), including anaphylaxis, which may result from allergic reactions to insect stings, biting insects, foods, drugs, sera, diagnostic testing substances and other allergens, as well as idiopathic anaphylaxis or exercise-induced anaphylaxis.

The treatment for allergic reaction in an infant is epinephrine (IM), as it is used for emergency treatment of allergic reactions (Type I), including anaphylaxis 2.

  • Key points:
    • Epinephrine is administered via intramuscular (IM) or subcutaneous use.
    • It is used to treat anaphylaxis and other allergic reactions.

From the Research

Treatment for Allergic Reaction in Infants

  • The first-line therapy for anaphylaxis, a life-threatening allergic reaction, is the immediate administration of intramuscular epinephrine 3.
  • In infants, anaphylaxis is typically triggered by exposure to egg, cow's milk, or peanuts, and symptoms can be underrecognized or misdiagnosed due to their non-specific nature, such as drooling, loose stools, and irritability 3.
  • Antihistamines can be used to treat symptoms of allergic diseases, including anaphylaxis, but their use in infants, especially those under 2 years of age, is often off-label due to limited data on safety 4.
  • The management of anaphylaxis involves removal of the trigger, early administration of intramuscular epinephrine, and supportive care for the patient's airway, breathing, and circulation 5, 6.
  • Updated guidelines recommend the use of a 0.15 mg adrenaline injector device for infants and children weighing 7.5-10 kg, and a 0.3 mg adrenaline injector device for those over 20 kg 7.

Administration of Epinephrine

  • Epinephrine should be administered promptly in the treatment of anaphylaxis, with no contraindications to intramuscular administration 7.
  • Correct positioning of the patient is vital, as death can occur within minutes if a patient stands, walks, or sits up suddenly 7.

Adjunctive Therapies

  • After epinephrine administration, adjunct medications such as histamine H1 and H2 antagonists, corticosteroids, beta2 agonists, and glucagon may be considered 5, 6.
  • Antihistamines, such as first- and second-generation antihistamines, can be used to treat symptoms of allergic diseases, but their use in infants requires careful consideration due to potential adverse effects 4.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Infant anaphylaxis: Diagnostic and treatment challenges.

Journal of the American Association of Nurse Practitioners, 2020

Research

Antihistamines: ABC for the pediatricians.

Pediatric allergy and immunology : official publication of the European Society of Pediatric Allergy and Immunology, 2020

Research

Anaphylaxis: Recognition and Management.

American family physician, 2020

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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