Food Protein-Induced Enterocolitis Syndrome

Food protein-induced enterocolitis syndrome (FPIES) is a condition that occurs in infants and young children, although it can rarely affect older children or adults as well. It typically causes vomiting and bloody diarrhea after consumption of certain foods (the trigger foods aren't the same for everyone). Severe reactions can prompt a medical emergency, such as dehydration, or even shock. Over time, FPIES can lead to malnutrition and weight loss and may affect childhood developmental milestones.

FPIES is often confused with classic food allergies since the reaction occurs after eating specific trigger foods; however, FPIES is caused by an immune reaction to common foods—it is not caused by a classic IgE antibody-mediated allergic reaction. Since most children with FPIES do not have allergic antibodies against the trigger food, allergy tests are often negative.

Young Patient with Stomach Ache

Fuse / Getty Images

Symptoms of FPIES

Symptoms of FPIES will occur within a few hours of eating the trigger food. Repeated episodes of severe vomiting usually start within three hours after eating the causative food, and diarrhea begins within five hours.

A child can quickly become dehydrated—signs include low blood pressure and lethargy. This reaction requires urgent medical care. It is common for a child who is having a reaction to look so sick that they may be preliminarily diagnosed with sepsis.

While FPIES can mimic food allergies, symptoms of FRIES typically consist only of gastrointestinal symptoms, and other organ systems remain unaffected. Severe food allergy symptoms include hives, face swelling, coughing, or wheezing. Effects of food allergies occur much more quickly than the effects of FPIES—often within a few minutes of eating the trigger food.

Foods That Cause FPIES

A variety of foods have been reported to cause FPIES. The most common culprits are milk and soy-based infant formulas. Reactions to infant formulas usually occur before 1 year of age, often within a few weeks of introducing the formula. Some infants with FPIES will react to both milk and soy.

The most common solid food to cause FPIES is rice cereal, although reactions to other cereal grains have also been reported. Children who develop symptoms of FPIES to one cereal grain have a 50% chance of developing symptoms of FPIES to another cereal grain. Other foods reported as causes of FPIES symptoms include legumes, avocado, banana, poultry, sweet and white potato, various fruits, fish, and shellfish.

Eggs rarely cause a reaction for children with FPIES. Most fruits and vegetables are not frequently a problem for children who have FPIES.

It is rare for a child over the age of one to develop new-onset FPIES to a newly introduced food; the exception is fish and shellfish, which have been known to cause FPIES even in older children and adults.

Diagnosing FPIES

When the effects are mild, it is common for FPIES to go undiagnosed for weeks to months, and the symptoms are often blamed on problems like viral gastroenteritis (stomach flu), another infection, or food allergies.

Allergy tests are usually negative, and foods that don't commonly cause allergies—like rice and poultry—are often overlooked as a possible cause.​

The diagnosis of FPIES is usually made on a clinical basis since there is no diagnostic test available to confirm the diagnosis.

An oral food challenge is not usually necessary. Some researchers suggest that patch testing to foods may be useful to confirm the diagnosis or to determine when a child has outgrown FPIES. However, this is not a standard or verified method of diagnosis in the clinical setting.


Avoidance of the trigger foods is the mainstay of treatment. If your young infant has FPIES caused by a cow’s milk-based infant formula, their pediatrician might also recommend avoiding soy formula, given that infants with FPIES to cow's milk can also have FPIES to soy. But it's not always necessary to avoid both—only if there is a strong risk of a reaction or if a reaction has been established.

Extensively hydrolyzed infant formulas (such as Alimentum and Nutramigen), in which the milk protein is broken down into small pieces) typically suffice for infants with FPIES. If these formulas are not tolerated, amino acid formulas can be used instead.

If your infant with FPIES has reactions after breastfeeding, your child's doctor might suggest that you avoid consuming cow's milk, soy, or other FPIES triggers.

If your child develops symptoms, emergency medical attention is necessary, given the potentially severe consequences. Intravenous (IV, in a vein) fluids, anti-emetics, and corticosteroids might be administered for the acute treatment of FPIES symptoms.

Children with FPIES are at high risk for nutritional deficiency and/or failure to thrive. To avoid nutritional deficiency, infants and children with FPIEs only need to avoid food(s) they react to. Concerns about any other foods should be discussed with your physician.

At What Age Does FPIES Resolve?

Typically, FPIES resolves by age 3, and your child is likely to eventually be able to tolerate the culprit foods. However, parents should not attempt to determine if the child can tolerate the food at home. Your child's allergist might perform an oral food challenge under close medical supervision. If your child has had a severe past reaction, the food challenges can be done with an IV catheter in place so that treatment can be administered quickly if needed.

1 Source
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Leonard S, Pecora V, Fiocchi A, Nowak-Wegrzyn, A. Food protein-induced enterocolitis syndrome: A review of the new guidelines.

    December 2018. World Allergy Organization Journal 11(1). doi:10.1186/s40413-017-0182-z

Additional Reading
  • Leonard SA, Nowak-Wegrzyn A. Food Protein-Induced Enterocolitis Syndrome: An Update on Natural History and Review of Management. Ann Allergy Asthma Immunol. 2011;107:95-101.

By Daniel More, MD
Daniel More, MD, is a board-certified allergist and clinical immunologist. He is an assistant clinical professor at the University of California, San Francisco School of Medicine and currently practices at Central Coast Allergy and Asthma in Salinas, California.