Food allergies are quite common: one in 13 children under the age of 18 has at least one food allergy. However, a small subset of infants and children will have a different type of allergy that affects the gastrointestinal tract and can be severe enough to cause failure to gain weight and grow. FPIES, or food protein induced enterocolitis syndrome, is the inability to tolerate the protein in one or more foods, resulting in a very sick child.

For these infants, allergy diagnosis begins with a sudden onset of severe vomiting and diarrhea 2-3 hours after ingestion of breast milk or formula containing cow’s milk or soymilk protein. The affected infant or child often appears dehydrated and lethargic. Often, they are taken to the emergency room, where their vital signs and blood can look like they have a severe infection. Typically, they will recover from the initial issue only to experience the same symptoms when they next eat the offending food. Over time, weight gain and growth can be negatively affected.

The allergies in FPIES are unlike those in a typical peanut or tree nut allergy. With a typical allergy, a child develops antibodies to a specific food protein, such as peanuts, and the body mounts an immune system response after exposure to that food protein. Allergists can test for those antibodies to determine what foods may have caused a reaction. In FPIES, the mechanism of allergic reaction is different. No antibodies are made and therefore diagnosis of the allergen is impossible based on lab tests. Parents and doctors are left with trial and error oral food challenges to determine which foods are intolerable. In infancy, treatment often means feeding the baby a formula free of both cow and soy proteins. As a child ages and begins to eat more foods, identifying the triggers can be much more difficult. It is important to introduce solid foods one at a time and very slowly for any infant who was previously diagnosed with FPIES. Children with FPIES must learn to avoid their triggers much the same way a child with a typical food allergy would.

Children with suspected FPIES are best cared for by pediatric allergists, pediatric gastroenterologists, or both in conjunction with their general pediatrician. Their weight gain and growth need to be carefully monitored, and dietary supplements may be recommended.

Decisions about how and when to initiate solids can be made together as the child grows and begins to eat more solids. FPIES tends to resolve itself over time, years later, so there may be a light at the end of the tunnel for these families.

Reviewed by Dr. Sara Connolly, March 2019


  • FPIES is a food allergy that affects the gastrointestinal tract.
  • Because there is no laboratory test for FPIES, it can be difficult to diagnose, often requiring ruling out other common illnesses before a diagnosis is reached.
  • Symptoms of FPIES normally occur 2-3 hours after ingestion of the food.
  • The care of a child with FPIES is often best done by an allergist or gastroenterologist in conduction with their pediatrician.


  1. Caubet JC, Ford LS, Sickles L, Järvinen KM, Sicherer SH, Sampson HA, Nowak-Węgrzyn A. Clinical features and resolution of food protein-induced enterocolitis syndrome: 10-year experience. J Allergy Clin Immunol. 2014 Aug;134(2):382-9. doi: 10.1016/j.jaci.2014.04.008.
  2. The FPIES Foundation. About Food Protein-Induced Enterocolitis Syndrome.
  3. The FPIES Foundation. Resources.


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