Emergent Care / Stabilization:
Acute management of food protein-induced enterocolitis syndrome focuses on supportive care, including early recognition of symptoms, ondansetron for vomiting, oral or intravenous fluid resuscitation for dehydration or shock, and close monitoring, with epinephrine reserved only for cases concerning for concurrent IgE-mediated anaphylaxis.

Diagnosis Overview:
Food protein-induced enterocolitis syndrome (FPIES) is an uncommon but severe nonimmunoglobulin E (IgE)-mediated gastrointestinal food hypersensitivity reaction to dietary proteins, with the notable absence of cutaneous findings. Even foods with low allergenic potential, including rice and bananas, can trigger FPIES. FPIES usually manifests in infancy, although adult-onset is being increasingly recognized.

The etiology of FPIES is incompletely understood but is thought to be due to pan-leukocyte activation, cytokine release, and increased gastrointestinal permeability.

FPIES can be classified as acute, chronic, adult-onset, and atypical. The most common subtype is acute FPIES, affecting approximately 90% of individuals. It typically presents in infants and is characterized by repetitive vomiting occurring 1-4 hours after ingestion of the culprit food, followed by diarrhea within 24 hours. Patients may develop metabolic derangements, significant dehydration, and inflammation. In 15%-20% of cases, patients go into hypovolemic shock. Chronic FPIES presents with chronic / intermittent emesis, diarrhea, low albumin and total protein, anemia, and failure to thrive. It predominantly affects formula-fed infants, with symptoms typically beginning 4 weeks after formula introduction. Atypical FPIES is defined by the coexistence of FPIES and evidence of food-specific IgE sensitization (positive serum IgE or skin prick testing) to the trigger food. Compared with classic FPIES, atypical FPIES carries a higher risk of evolving into IgE-mediated food allergy. FPIES can also occur in adolescents and adults, typically presenting with acute reactions. Seafood is the most common trigger worldwide. Compared with children, adults are more likely to present with abdominal pain and diarrhea rather than vomiting, and severe cases may include hematochezia or hypotension. Adult FPIES shows a female predominance.

Most children with FPIES eventually develop tolerance, typically by preschool or early school age, although the timing varies by trigger. Milk, soy, and grain FPIES generally resolve by age 3-5 years, while fish and some solid-food triggers may have a more prolonged course. Egg FPIES, atypical FPIES, and adult-onset FPIES may be associated with more persistent disease and require closer monitoring, particularly for progression to IgE-mediated food allergy in sensitized patients. Adult-onset FPIES often persists, with only a minority achieving tolerance over several years.

FPIES is associated with a higher prevalence of atopic conditions (eg, food allergy, asthma, allergic rhinitis, atopic dermatitis, and eosinophilic esophagitis), with some patients developing IgE-mediated food allergy over time.