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A New Food “Allergy” of Infancy: Food Protein Induced Enterocolitis Syndrome (FPIES)

My oldest daughter, Grace, had horribly bad reactions to cow’s milk protein as an infant, which included vomiting, chronic diarrhea with mucus, irritability, reflux, and poor growth. Her first reaction occurred shortly after getting her initial supplemental bottle of formula. She was predominantly breastfed at first, but I did have to supplement her due to milk supply issues (which, looking back, I believe were a result of my undiagnosed Celiac Disease). She went through a series of formula changes (from regular to soy to Alimentum and Nutramigen), and it was not until she was started on Neocate, an amino acid based formula, at 2 months, that she began to grow and thrive. Looking back, I am pretty sure that she had food protein induced enterocolitis syndrome, which is also called FPIES.

FPIES is a severe food sensitivity/intolerance which causes digestive symptoms in infants. Although it is considered by many to be an “allergy,’” it does not involve the formation of IgE antibodies like other food allergies. The most common triggers for FPIES in babies are cow’s milk and soy proteins, although rice, oats, barley, fruits, and vegetables have also been documented as triggers for older infants who have been started on solid foods. Based on recent studies it is believed that 0.3% of infants have an FPIES reaction to cow’s milk. This is in addition to the 3-5% of infants who have milder non-IgE reactions (allergies) to cow’s milk protein during the first year of life.

Infants with FPIES have symptoms shortly after consuming cow’s milk and/or soy proteins, usually within 1-4 hours. The usual trigger is a cow’s milk based formula, but breast fed infants can react to milk proteins in their mother’s breast milk as well. Symptoms can include projectile vomiting, chronic diarrhea with blood and/or mucus, low blood pressure, lethargy, irritability, and/or an elevated white blood cell count. 50% of infants with FPIES who react to milk will also react to soy.

It has recently been recognized that older infants can develop FPIES after solid foods are introduced during the 2nd six months of life. Rice is the most common trigger, followed by oats, barley, chicken, turkey, egg whites, green peas, peanuts, and potatoes. I recently learned that 80% of infants with one solid food trigger will have reactions to at least one other food, and that it is common for infants to have FPIES reactions to multiple foods.

Diagnosing FPIES is difficult because there are currently no blood tests that can be used in detection. This is because the immune reaction of FPIES does not involve the formation of IgE antibodies against the offending foods. This is much different than the IgE-mediated immune reaction that occurs in older children with food allergies. IgE allergies can be detected by blood and/or skin testing.  If a baby has adverse reactions after multiple exposures to the same food, FPIES can be diagnosed clinically. If the diagnosis is unclear, an oral food challenge (OFC) should be performed. It is recommended that an OFC be performed under close medical supervision (i.e. doctor’s office), as there is a risk for low blood pressure and/or dehydration to develop during a food challenge. In the worst cases an infant can develop shock. In some cases infants may need IV fluids after a reaction. Steroids are sometimes needed in severe cases. Based on what I have read, it seems that reactions to trigger foods may get more severe with time, i.e. it may take less and less of the offending food to trigger a reaction.

Research has shown that FPIES to milk and/or soy protein resolves by 3 years of age. It is recommended that children with FPIES get oral food challenges every 12 to 24 months. My oldest daughter is now 7 years old and she has no problems with dairy products (she eats yogurt, cheese, and ice cream) but she has refused to drink plain cow’s milk and has a tendency to avoid soy as well.

Reading and learning about FPIES led me to have many questions and concerns:

1. Why are so many infants born with this problem and why is it increasing in severity? Is it somehow related to their moms having undiagnosed Celiac Disease, and/or some other process causing “leaky gut” while pregnant?

2.  Is this the same disease process which those of us who have multiple food intolerances are experiencing, only babies are getting sicker and having more severe reactions since their immune and digestive systems are less mature?

3. How under-diagnosed is this problem? I had never heard of it 7 years ago when my daughter had it (and I was in my pediatric residency at the time). What are the real numbers?

4. Do infants with FPIES go on to develop Celiac Disease or gluten sensitivity when they are older? Is FPIES, even though it resolves, some sort of marker for the future development of food issues in a patient?

5. Is this somehow linked to the dramatic increase in autism over the last few years? Do the FPIES episodes have some sort of effect on the developing brain of an infant?

6. Does the microflora of the gut play a role? Would probiotics prevent and/or ameliorate the problem?

7. I was going to speculate a bit about GMOs, but I am not sure that I am ready to write about that yet…

I suspect that we are going to hear a lot more about this problem in the future. I wrote this article to share the little which I know about FPIES with you, in hopes that we can learn about it together.


1. American Academy of Allergy, Asthma, and Immunology website: www.acaai.org/allergist/allergies/Types/food-allergies/Pages/food-protein-induced-enterocolitis-syndrome-fpies.aspx

2. Medscape Pediatrics. “FPIES: The ‘Other” Food Allergy.” Dr. Anna Nowak-Wegrzyn, MD. Published online April 3, 2013.

3. Curr Opin Pediatr. 2012 Dec;24(6):739-45. Clinical diagnosis and management of food protein-induced enterocolitis syndrome. Leonard, S. and Nowak-Wegrzyn, A. www.ncbi.nlm.nih.gov/pubmed/23042254

4. Clin Exp Allergy. 2012 Aug;42(8):1257-65. A multicentre retrospective study of 66 Italian children with food protein-induced enterocolitis syndrome: different management for different phenotypes. Sopo, S., et al. Department of Pediatrics, University of Sacred Heart Agostino Gemelli Rome, Rome, Italy. www.ncbi.nlm.nih.gov/pubmed/22805473