What is FPIES?

Food protein-induced enterocolitis syndrome (FPIES) is a rare food allergy. It affects mostly young children and infants. This allergy occurs in the gastrointestinal (GI) tract. It causes recurring or sometimes chronic — but often severe — vomiting and diarrhea.

The reaction typically begins after the infant or child consumes dairy or soy foods. The allergy may also appear when the infant begins eating solid foods for the first time.

Some children with FPIES will struggle to gain or even maintain a healthy weight. As a result, they may begin failing to meet growth milestones, including weight and height goals. Ultimately, children with FPIES may be diagnosed with “failure to thrive.”

Unlike other food allergies, an FPIES reaction is contained to the GI tract. The signs of a reaction may take several hours to appear. This delay may make it harder to diagnose the allergy.

Symptoms of FPIES may also be confused with gas, acid reflux, or a stomach bug. The symptoms return after each exposure to the food allergen, so it’s the chronic and repetitive nature of FPIES and the association with one particular food that ultimately distinguishes it from a brief episode of tummy trouble. The signs and symptoms of FPIES include:

  • chronic or recurrent vomiting
  • diarrhea
  • dehydration
  • lethargy
  • changes in blood pressure
  • body temperature fluctuations
  • weight loss
  • stunted growth
  • failure to thrive

A child with a diagnosis of failure to thrive may have delays in many milestones, including:

  • height, weight, and head circumference
  • physical skills, including rolling over, sitting, standing, and walking
  • social skills
  • mental skills

There are several risk factors for FPIES:

  • FPIES appears to affect boys slightly more than girls.
  • According to the American College of Allergy, Asthma, and Immunology (ACAAI), 40 to 80 percent of children with FPIES have a family history of allergic conditions, including food allergies, eczema, or hay fever.
  • If your child received a diagnosis with one type of food allergy, it’s possible they may have an additional allergy. FPIES is unlike most food allergies, which cause reactions within several seconds or minutes of contact with the allergen. Your child might have both types of food allergies.


All foods can cause an FPIES reaction, but certain foods are also more likely to trigger one. Milk and soy products are the leading causes of a reaction. Usually the food must be ingested directly by the infant, so breastfed babies develop symptoms later than formula-fed babies — if they get symptoms at all. Other food allergens that might trigger it include:

Most children with FPIES only have one or, occasionally, two food triggers. It’s possible, however, for a child to have reactions to multiple foods.

Experts don’t know how many children have FPIES. It’s considered a rare disease. In recent years, the number of FPIES cases has been increasing. It’s unclear if this increase is the result of wider awareness for FPIES or an actual increase in cases of the condition.

If your child is exposed to the allergen that causes their reaction, you have several options for treating the symptoms. The treatment options depend on the severity of your child’s reaction and what foods trigger their reactions.

Steroid injections

A steroid shot may help reduce the severity of your child’s immune response. This may lessen the severity of symptoms, too.

IV fluids

If your child is experiencing severe vomiting, diarrhea, or dramatic changes in body temperature, see their pediatrician immediately. Your child may need IV fluids for rehydration and to prevent shock.

Lifestyle treatments

These treatments help reduce or ease the symptoms of an FPIES reaction. They don’t treat the condition itself, though. Treatments are individualized to your child and their triggers.

Once an infant or young child receives an FPIES diagnosis and their trigger food is eliminated from their diet, symptoms resolve. Most children outgrow FPIES by the time they’re 3 years old. However, cases in older children and adults have been reported.

If your child has a reaction to a milk product, including cow’s milk, soy, or another type, your pediatrician may recommend a hypoallergenic formula.

It’s rare for a child to react to their mother’s breast milk. But if they do, their doctor may recommend you switch to a formula temporarily. Then, while pumping to maintain your supply, you can work with your child’s doctor to determine the exact allergy so that you can remove it from your diet and begin breastfeeding again.

If your child only reacts to one or two foods, they can simply avoid eating them. Ultimately, the best course of management and treatment for FPIES is to avoid the allergen altogether.

It may take several weeks or months to get a diagnosis of FPIES. Then, you’ll have to change your child’s lifestyle to meet the new restrictions that come with the diagnosis.

Fortunately, FPIES isn’t a lifelong condition. In fact, according to the ACAAI, most children will outgrow FPIES by age 3 or 4.

Once the doctor — usually an allergist or gastroenterologist — believes your child has outgrown their allergy, they’ll work with you to begin slowly introducing the trigger foods back into your child’s diet. They may also recommend you work with a dietitian experienced in working with those who have allergies.

Your child’s allergist may want you to do food exposure tests in their office, where your child can be monitored. Once the doctor is satisfied that the trigger no longer causes an allergic reaction, you may begin feeding your child these foods again.

Unfortunately, some children may live with the condition beyond their earliest years. Some children with FPIES will live with it into their adolescence and beyond. Thankfully, proper diet and FPIES control can help your child grow and thrive, despite the condition.

If your child shows signs of FPIES, make an appointment to speak with their doctor. Identify the signs and symptoms your child experiences and when they occur. Testing for FPIES is limited and not very certain, so your child’s doctor may conduct several tests to eliminate other conditions.

After those conditions are ruled out, their doctor may consider an FPIES diagnosis more likely. If, under the care of their doctor, eliminating the suspected trigger food from your child’s diet causes the symptoms to go away, this helps make the diagnosis. Together, you can begin developing ways to help your child live and cope with the new diagnosis.