What Is Food Protein-Induced Enterocolitis Syndrome?

Medically Reviewed by Carol DerSarkissian, MD on November 02, 2022
3 min read

When most kids have an allergic reaction to a food, like peanut butter, you see signs right away. But if your child has a rare allergy called food protein-induced enterocolitis syndrome (FPIES), the reaction may not happen until a few hours after they eat.

Unlike other food allergies, this one won't make your child wheeze, break out in hives, or get a rash. Instead, they may vomit or get diarrhea. So you might think your child has a virus or a bug from spoiled food.

FPIES typically starts when your child has formula or solid food. Breast milk doesn't usually trigger it, but it is possible.

Many kids outgrow the allergy by age 3 or 4.

You may notice that a couple of hours after your baby eats, they vomit over and over and then get diarrhea. Some children have symptoms that get worse over time, and they may not grow like they should.

Severe attacks can lead to dehydration and shock. That can cause a sudden drop in blood pressure or body temperature. If you notice these signs, take your child to the hospital right away:

  • Apparent confusion
  • Cool or clammy skin
  • Extreme thirst
  • Pale or even blue skin
  • Shallow breaths
  • Sluggishness or tiredness
  • Weak pulse


The syndrome is caused by cells in your child's immune system that react badly to certain foods. This leads to a severe reaction in the gastrointestinal tract. But you may not see symptoms until 2 to 8 hours later.

About 40% to 80% of kids who have the allergy have family members who also have other types of allergies such as hay fever or eczema skin rashes. Only 20% of kids with FPIES have family members with food allergies.

Milk and dairy products, soy or soymilk, and wheat or other grains are the most common foods that cause an attack.

Some kids also can be allergic to foods like the ones below that we don't usually think of as triggers:

  • Barley
  • Chicken or turkey
  • Fish
  • Green beans
  • Oats
  • Peas
  • Rice
  • Squash
  • Sweet potatoes


If you think your child has FPIES, see an allergist or pediatric gastroenterologist (a doctor who specializes in children's digestion issues). Your child's doctor will ask you about their symptoms and your family history of allergies.

First, the doctor will rule out other common causes of vomiting or diarrhea. Then they'll test your child for allergies.

In some cases, blood tests and atopy patch tests (APT) can help show what's wrong. An APT involves putting a possible trigger food into a metal cap that's put on your child's skin for 48 hours to see if there's a reaction. But these tests can't confirm that your child has FPIES.

The only way to tell for sure is to do something called an oral food challenge, or OFC. Your child will eat foods you think may be triggers to see if there's a reaction. This will be done in a clinic or hospital.

Remove your child's trigger foods from their diet. If your baby needs formula, use hypoallergenic brands that don't have soy or dairy.

Be sure to check all package labels for triggers.

It's also a good idea to get a letter from their doctor that explains that they have FPIES. Keep it with you in case they have a severe reaction and you need to let medical staff know what's wrong.