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Understanding FPIES: A Guide for Parents


Food Protein-Induced Enterocolitis Syndrome (FPIES) is a serious type of food allergy that commonly affects infants and young children. Unfortunately, it is often missed or misdiagnosed, which can be dangerous if left untreated. In this article, we will explore what FPIES is, its symptoms, common triggers, and how it is diagnosed and treated.

What is FPIES?

FPIES is a food allergy that affects the digestive system. Unlike other food allergies that cause an immediate immune response, FPIES can exhibit a reaction either immediately or delayed, up to several hours after consuming a trigger food. It's important to note that FPIES symptoms can show up as acute (meaning they occur suddenly, can escalate quickly, and have a limited duration), or chronic (meaning they are long lasting and can worsen over time).

Another key hallmark of FPIES is that the initial reaction often occurs after several exposures to a food. The allergic responses we are most familiar with typically happen the very first time a person consumes that food. With FPIES, it is very common to hear stories like:

“She has been eating oats for the past several days, then all of the sudden…”
”He ate bananas for three days then we ran out. The next time I went to the store I picked up some more and that day…”

FPIES has been further broken down into two main categories of reactivity: acute and chronic.

Acute FPIES is characterized by repetitive vomiting within 1 to 4 hours of culprit food ingestion and may be associated with lethargy, hypotonia, pallor, hypothermia, with or without diarrhea. Reactions typically resolve within 24 hours, and patients are healthy between the episodes.⁣

Chronic FPIES is characterized by frequent vomiting and diarrhea over days to weeks, associated with poor weight gain or weight loss. In infants, chronic reactions most often manifest 6-8 hours after ingesting a trigger, however some may take 48 hours or longer depending on how frequently they are stooling. Symptoms typically begin to resolve within that 48 hour window but can take several weeks for full healing [1]. The total time for gastrointestinal healing after a reaction is dependent on how severe the response was. Read more about reaction and healing timing here.

Common Triggers

Any food can trigger FPIES, but the most common triggers are milk, soy, rice, and oats. Other potential triggers often experienced include grains, fruits, and vegetables. It's important to note that some children with FPIES have multiple triggers. In fact, in a study of 441 participants, the median number of trigger foods was 3 with a range of 1 to 13 total culprit foods [2]. Additionally, some patients find that reactions can be dose-dependent. This means that a small amount of a trigger food may not cause a reaction, but a larger amount can lead to a severe reaction.

Can a Baby React to Dietary Proteins Through Human Milk?

Yes. A plethora of research shows that lactating individuals transfer protein fragments from the gastrointestinal system to breastmilk through the circulatory system [3]. You can read more about these publications here. Parents transfer such a significant amount of these protein portions that they can elicit an allergic response in children who are reactive to those specific fragments [4]. And it is important to note that this transfer is biologically NORMAL! Our bodies are meant to expose our children to different components of food through nursing. In fact, exposure of certain foods like egg and peanut through the breast can reduce future allergies for children who are not already reactive to those items [5-6]. Learn more about “Early and Often” allergen introduction to reduce life long food allergies here.

Diagnosis and Treatment

FPIES can be difficult to diagnose because its symptoms can mimic other conditions such as a viral infection. In addition to a physical exam, doctors may perform blood tests and stool tests to rule out other conditions. An oral food challenge may also be used to diagnose FPIES. This involves giving the child a small amount of the suspected trigger food and monitoring their reaction [7].

Currently, there is no cure for FPIES, and the only treatment is to avoid the trigger food(s). In severe cases, hospitalization may be necessary to manage dehydration and shock. Infants may require a special hypoallergenic formula or elimination diet breast milk.

While there is no cure, there is good news. Actually, GREAT news. A vast majority of children with FPIES outgrow the condition, with reports as high as 97% in some research studies [8]. Some little ones outgrow this type of reactivity by the time they reach 9 months old, while others may by five or older before celebrating their final food trial pass.

Why Some Providers May Not Be Aware of FPIES

For doctors to know how to diagnose and properly treat an illness, they need clear guidelines for how to recognize and understand it. But it took almost 50 years after the first cases of FPIES were discovered for experts to come up with these guidelines. It wasn’t until 2017 that group of doctors called the AAAAI worked together to create the International Consensus Guidelines for the Diagnosis and Management of FPIES [1]. This document lays out the important signs and symptoms of FPIES so medical professionals can properly diagnose and treat it. Since these guidelines are still fairly new, many doctors may not have had the chance to learn about FPIES in detail.

If this is a frustration you have experienced, you are not alone. In a 2022 publication by Vaquez-Ortiz, et. al titled, “Challenges and unmet needs in FPIES from the parents and adult patients’ perspective: An international survey” it was found that the top unmet need for food allergy families was awareness and knowledge among health care professionals to avoid delay in diagnosis with a mean score of 8.7 out of 9 (285 participants each scored from 9 (absolutely essential) to 1 (not essential)) [9].

Want to help spread awareness about infant food allergies? Snag a set of our FREE resource pamphlets to share at your next appointment.


We understand that dealing with FPIES can be challenging and overwhelming for both parents and children. If you suspect that your child is having an FPIES reaction, it's important to seek medical attention immediately. With proper diagnosis and management, children with FPIES can live healthy and happy lives. We want you to know that you are not alone in this journey.

For those of you who may be struggling to communicate your little one's FPIES with family and friends, we've created a special handout just for you!

Friends and Family Info Sheet-Free to Feed
Download PDF • 9.89MB

Remember You Have Options & You’re Not Alone

Our team at Free to Feed is here to support you every step of the way. We offer consultations with our allergy experts who can help you navigate your next steps. We also have a free app that helps you track food intake and log your baby’s symptoms. For nursing parents, we can help you craft a custom elimination diet plan that empowers you to identify your food triggers while continuing to nourish your body with the nutrients you and your baby need.

We also offer a Flourishing with FPIES Master Class ($59), designed to provide you with the knowledge and tools you need to identify, navigate, and thrive through FPIES with your little one. Our course is tailored for parents of food-allergic children experiencing symptoms such as reflux, mucus/bloody stools, vomiting, and more through breast milk, formula, and/or solids. We provide guidance on acute and chronic FPIES symptoms, reactivity treatments, finding experienced medical professionals, food trialing, and a starter list of low reactivity foods.

This course is not just for parents, but also for lactation and medical professionals looking for the most current research on FPIES and how to empower parents through their journey. We believe that everyone involved in the care of a child with FPIES can benefit from learning the latest information and best practices.

Remember, you have options, and you don't have to face FPIES alone!

Free Resources


This blog post provides an overview of Food Protein-Induced Enterocolitis Syndrome (FPIES), a rare and potentially severe type of food allergy that affects mostly infants and young children. The post covers what FPIES is, its symptoms, common triggers, and how it is diagnosed and treated. The only treatment for FPIES is to avoid trigger foods, and in severe cases, hospitalization may be necessary to manage dehydration and shock during a reaction. Parents of children with FPIES should work closely with their doctor to develop a comprehensive management plan that includes emergency protocols, dietary restrictions, and ongoing monitoring.

FPIES can be a difficult and scary diagnosis for parents, but with proper understanding and management, children with FPIES can lead healthy and happy lives. If you suspect that your child may have FPIES, it is important to seek medical attention and work closely with your doctor to develop a management plan that meets their unique needs. By staying informed and vigilant, parents can help their children thrive despite this challenging condition.


[1] 📖 Bartnikas, Lisa M., et al. "The evolution of FPIES: from a diagnosis that did not exist to a condition in need of answers." Annals of Allergy, Asthma & Immunology (2021).⁣

[2] 📖 Maciag, Michelle C., et al. "A Slice of Food Protein–Induced Enterocolitis Syndrome (FPIES): Insights from 441 Children with FPIES as Provided by Caregivers in the International FPIES Association." The Journal of Allergy and Clinical Immunology: In Practice 8.5 (2020): 1702-1709.

[3] 📖 Zhu, Jing, et al. "Discovery and quantification of nonhuman proteins in human milk." Journal of proteome research 18.1 (2018): 225-238.

[4] 📖 Dekker, Pieter M., et al. "Maternal allergy and the presence of nonhuman proteinaceous molecules in human milk." Nutrients 12.4 (2020): 1169.

[5] 📖 Azad, Meghan B., et al. "Reduced peanut sensitization with maternal peanut consumption and early peanut introduction while breastfeeding." Journal of Developmental Origins of Health and Disease 12.5 (2021): 811-818.

[6] 📖 Verhasselt, Valerie, et al. "Ovalbumin in breastmilk is associated with a decreased risk of IgE-mediated egg allergy in children." Allergy 75.6 (2020): 1463-1466.

[7] 📖 Bird, J. Andrew, et al. "Food protein-induced enterocolitis syndrome oral food challenge: Time for a change?." Annals of Allergy, Asthma & Immunology 126.5 (2021): 506-515.

[8] 📖 Cianferoni, Antonella. "Food protein-induced enterocolitis syndrome epidemiology." Annals of Allergy, Asthma & Immunology 126.5 (2021): 469-477.

[9] 📖Vazquez-Ortiz, Marta, et al. "Challenges and unmet needs in FPIES from the parents and adult patients’ perspective–an international survey." The Journal of Allergy and Clinical Immunology: In Practice (2022).


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