Differential Diagnosis for Infant Food Allergic Reaction

When considering the potential causes of an infant's symptoms after consuming food, it's crucial to approach the situation with a broad differential diagnosis to ensure no critical conditions are overlooked. The following categorization helps in systematically evaluating the possible causes:

• Single Most Likely Diagnosis
  • IgE-mediated food allergy: This is the most common type of food allergy, involving an immune system reaction that can cause symptoms ranging from mild (hives, itching) to severe (anaphylaxis, which is life-threatening). Common allergenic foods include peanuts, tree nuts, milk, eggs, fish, shellfish, wheat, and soy. The justification for this being the single most likely diagnosis is the prevalence and well-documented nature of IgE-mediated reactions in infants.
• Other Likely Diagnoses
  • Non-IgE-mediated food allergy: These reactions do not involve the immune system's IgE antibodies and can cause symptoms like blood in stool, vomiting, and diarrhea. They are often seen in conditions like food protein-induced enterocolitis syndrome (FPIES) or food protein-induced allergic proctocolitis.
  • Lactose intolerance: Though not an allergy, this condition involves the inability to digest lactose, a sugar found in milk, leading to symptoms like bloating, gas, and diarrhea after consuming lactose-containing products.
  • Gastroesophageal reflux disease (GERD): While not directly related to food allergies, GERD can cause discomfort and vomiting in infants, sometimes mistaken for an allergic reaction.
• Do Not Miss Diagnoses
  • Anaphylaxis: A severe, life-threatening allergic reaction that requires immediate medical attention. Symptoms can include difficulty breathing, rapid heartbeat, dizziness, and a drop in blood pressure, among others. The potential for anaphylaxis to be deadly if not promptly treated makes it a "do not miss" diagnosis.
  • Food protein-induced enterocolitis syndrome (FPIES): A type of non-IgE-mediated food allergy that can cause severe vomiting, diarrhea, and dehydration, typically after the ingestion of common foods like milk, soy, or rice.
• Rare Diagnoses
  • Eosinophilic esophagitis (EoE): A chronic immune system disease in which a type of white blood cell, the eosinophil, builds up in the esophagus in response to an allergen or irritant, leading to difficulty swallowing and food impaction.
  • Heiner syndrome: A rare condition associated with a hypersensitivity reaction to cow's milk, leading to pulmonary infiltrates and other systemic symptoms.

Each of these diagnoses has a distinct set of symptoms and diagnostic approaches, emphasizing the importance of a thorough medical evaluation to accurately determine the cause of an infant's reaction to food.