What is food protein-induced enterocolitis syndrome (FPIES)?

Food protein-induced enterocolitis syndrome (FPIES) is a rare food allergy that affects the gastrointestinal (GI) tract. Unlike most food allergies, symptoms of FPIES do not begin immediately after eating. Instead, it can take hours before severe symptoms begin.

The most common FPIES food triggers are cow’s milk, soy, rice and oats, but any food can cause FPIES symptoms. Typical symptoms of FPIES include severe vomiting, diarrhea and dehydration two hours after eating. These symptoms can lead to other complications, including changes in blood pressure and body temperature, lethargy, and failure to thrive.

FPIES is commonly misdiagnosed as a severe stomach bug because the symptoms are so similar. It is generally only after repeated ingestion of the trigger food — followed by severe symptoms hours later — that indicate FPIES may be the cause.

Causes

When a child with FPIES eats a trigger food — whether it is milk, rice, oats or another food — symptoms develop. When the trigger food is removed from the child’s diet, FPIES symptoms subside.

The age in which FPIES symptoms begin to develop depends on a variety of factors but in general, infants who are bottle fed show symptoms earlier than infants who are exclusively breastfed. For bottle fed infants, FPIES reactions may begin in the first few months of life if reactions are due to milk, soy, or, at times, rice.

For exclusively breastfed infants, FPIES reactions generally only begin when other foods are added to their diet. However, we have had babies who do not tolerate foods in maternal diet (although reactions are not as severe.) Typically, the child must directly ingest the trigger food for symptoms to develop.

Signs and symptoms

Symptoms of food protein-induced enterocolitis syndrome can vary from child to child and in severity. Symptoms may include:

• Vomiting, typically occurring two hours after ingestion
• Diarrhea that begins after vomiting
• Dehydration
• Severe lethargy
• Changes in blood pressure and body temperature

For the majority of children with FPIES, growth is normal and the child is healthy as long as he or she avoids trigger foods. For children with chronic FPIES, there may be growth concerns or concomitant gastroesophageal reflux.

Testing and diagnosis

Diagnosing FPIES can be challenging. It can be difficult to find the specific trigger food or foods affecting your child, as symptoms don’t develop immediately after ingestion. Some children with FPIES may also have an additional food allergy, which can complicate appropriate diagnosis.

Additionally, sometimes FPIES triggers do not show up on standard allergy tests such as a skin prick test (SPT) or a blood test that measures food IgE antibodies (RAST). A negative allergy evaluation may actually delay the diagnosis in some cases because a food trigger (such as cow’s milk) may be incorrectly eliminated as a cause of the delayed symptoms that FPIES produces.

At The Children’s Hospital of Philadelphia, an FPIES diagnosis is generally made by an experienced allergist or gastroenterologist who considers the child’s medical history and symptom presentation, and by excluding other possible illnesses.

Other tests that may be performed include:

• Blood tests — Tests performed during a reaction may be helpful; the results may mirror the child’s response to infection.
• Supervised oral food challenge test — The child is given the food that is the suspected “trigger” in a controlled, clinical environment and monitored for a response.