What is FPIES | FPIES Explained

What is FPIES? Learn how to get an FPIES diagnosis and what to do next, from managing symptoms to starting food trials.

I’m often asked, “What is FPIES?” I receive numerous emails and messages on Facebook from parents seeking answers, which is why I wrote this blog post. If you’re unfamiliar with FPIES or have recently received a diagnosis, please know you’re not alone.

There is so much more information available about FPIES now than there was before. More doctors are knowledgeable as well as hospitals.

However, when it comes to treatment and diagnosis, not much has changed over the past 12 years. It still requires a clinical diagnosis. The approach remains largely the same: avoiding trigger foods, careful monitoring, and relying on symptom history for diagnosis, as standard allergy tests cannot detect FPIES.

Food Protein-Induced Enterocolitis Syndrome (FPIES)

FPIES is not your typical food allergy. Unlike IgE-mediated allergies—which often present with hives, rapid reactions, or even anaphylaxis.

FPIES is a non-IgE-mediated condition. This means it primarily causes internal symptoms, although some children may experience external manifestations like eczema.

What’s the Difference Between FPIES and a Nut Allergy?

This is a common question, and it boils down to the two types of allergic responses: IgE-mediated and Non-IgE-mediated.

Typical Food Allergy (IgE-mediated):

• Fast reactions (minutes to an hour after ingestion)
• Hives, eczema
• Anaphylaxis (life-threatening and requires immediate treatment with epinephrine)
• Both internal and external manifestations
• Positive results in skin prick or blood tests
• IV fluids help stabilize vital signs alongside other treatments like antihistamines or steroids if needed.

FPIES (Non-IgE-mediated):

• Slow, delayed reactions (2-3 hours after ingestion)
• Negative skin prick or blood tests, FPIES cannot be detected through standard allergy testing
• Internal manifestations such as vomiting, diarrhea, lethargy
• Chronic cases may present symptoms for 7 days or more
• Some children also experience external symptoms like eczema
• IV fluids are essential to manage dehydration and shock in acute cases.

Recognizing FPIES

FPIES often first appears when introducing milk, soy, or even breastmilk to an infant’s diet. While reactions through breastmilk are rare, they can happen, and mothers may need to eliminate trigger foods from their diet to continue breastfeeding.

In our case, Sweet Baby’s FPIES journey began when she started solid foods. Her first reaction was to chicken, and when she showed the same symptoms after trying oats, we knew it was more than a simple virus. After some research online and support from BabyCenter, I self-diagnosed her with FPIES.

We immediately contacted her doctor, joined FPIES-focused Facebook groups, and made an appointment at the Children’s Hospital of Philadelphia (CHOP). Within a month, we had a confirmed diagnosis. Our pediatrician was unfamiliar with FPIES, but with the help of resources from the IAFFPE (now I-FPIES), we found experienced doctors and an abundance of reliable information.

For families navigating FPIES, the key is persistence, research, and finding the right healthcare team to support your child’s unique needs.

Our Journey with FPIES

My daughter suffered from FPIES reactions for two months before we finally figured out what was going on. For many families, the road to diagnosis is even longer. Parents often endure countless tests, doctor appointments, and significant expenses before learning what’s causing their child’s distress.

The most common FPIES triggers are milk, soy, rice, and oat, but each child’s triggers can vary. For our Sweet Baby, the known triggers so far are soy, chicken, and oats. My son also experienced FPIES, with dairy as his primary trigger. In addition to FPIES, he has anaphylactic allergies, which are very different. While FPIES reactions typically involve delayed gastrointestinal symptoms, anaphylactic reactions are immediate and life-threatening, requiring prompt treatment with epinephrine.

Recently, we trialed rice. During the trial, we feared a reaction might be occurring, but blood work revealed it was just a virus. Elevated white blood cell counts are common with viral infections. However, in an acute FPIES reaction, blood tests can show:

• Elevated white blood cell count with increased neutrophils and eosinophils
• Elevated platelet count
• Anemia (low red blood cell count)
• Low albumin levels (particularly in chronic cases)
• Severe episodes may lead to methemoglobinemia (reduced oxygen-carrying capacity of the blood).

Differential Diagnoses

It’s important to recognize that other conditions can mimic FPIES symptoms, making diagnosis challenging. These include:

• GERD (Gastroesophageal Reflux Disease):
  GERD occurs when stomach acid flows back into the esophagus, causing irritation. Symptoms like vomiting, fussiness, and refusal to eat can overlap with FPIES, but GERD often presents with acid reflux, regurgitation, and discomfort after feeding.
• Gastritis (Stomach Irritation):
  Gastritis involves inflammation of the stomach lining, which can cause nausea, vomiting, and stomach pain. Unlike FPIES, it may be triggered by infections (like H. pylori), certain medications, or stress.
• EoE (Eosinophilic Esophagitis):
  EoE is a chronic immune condition where white blood cells build up in the esophagus, leading to difficulty swallowing, food impaction, and vomiting. It’s commonly triggered by food allergens, similar to FPIES, but can be differentiated by esophageal biopsies.
• EG/EGE (Eosinophilic Gastritis/Gastroenteritis):
  These conditions involve inflammation and high eosinophil counts in the stomach or intestines. Symptoms include chronic diarrhea, vomiting, and abdominal pain, which overlap with chronic FPIES but are diagnosed via endoscopy and biopsy.

Other potential causes of similar symptoms include infectious gastroenteritis (caused by bacteria or viruses), metabolic disorders (which may lead to vomiting and poor growth), and food intolerances (such as lactose intolerance). Each of these has distinct diagnostic markers, which highlights the importance of thorough evaluations.

This is why consulting a healthcare professional experienced in FPIES is crucial. They’ll ensure an accurate diagnosis through testing, symptom monitoring, and possibly biopsies, allowing for a targeted treatment plan tailored to your child’s needs.

FPIES Facts:

General Facts

• FPIES can occur with any food, though common triggers include dairy, soy, oats, rice, and certain vegetables.
• 60-90% of children with FPIES outgrow it by age 3, but some cases persist into adulthood.
• Acute reactions often require intravenous hydration and Zofran via IV to manage severe vomiting.
• Trigger food avoidance remains the only treatment, as there is no cure for FPIES.
• More research is needed to better understand and treat this condition.

Acute FPIES Reactions

• Symptoms occur 2-3 hours after ingesting a trigger food.
• Profuse vomiting, dry heaving, bile
• Lethargy, limpness
• Dehydration, low blood pressure
• 20% of cases: Progression to shock
• 10% of cases: Methemoglobulinemia (reduced oxygen-carrying capacity of blood)
• 6-8 hours post-ingestion: Diarrhea may follow
• Congestion or cold-like symptoms, including loose stools, may develop over the following days.

Chronic FPIES Reactions

• Chronic diarrhea
• Blood and mucus in stools
• Intermittent vomiting
• Poor growth or weight loss, potentially leading to failure to thrive
• Symptoms typically resolve within a week once the trigger food is removed, though in severe cases, extended gut rest may be necessary.

Finding Safe Foods

Identifying safe foods for a child with FPIES is often challenging. Foods that are safe for one child may be triggers for another. The only way to determine safety is through carefully monitored food trials.

When we first started solids, we were naturally cautious due to our family history of food and seasonal allergies. Following our pediatrician’s advice, we introduced one new food every 3-4 days. However, our baby’s reactions didn’t resemble typical food allergies, leading us to the diagnosis of FPIES.

While the journey can feel overwhelming, with time, patience, and support, you’ll find your way to a safe and healthy diet for your child.

Finding Safe Foods

Identifying safe foods for a child with FPIES is often challenging. Foods that are safe for one child may be triggers for another. The only way to determine safety is through carefully monitored food trials.

When we first started solids, we were naturally cautious due to our family history of food and seasonal allergies. Following our pediatrician’s advice, we introduced one new food every 3-4 days. However, our baby’s reactions didn’t resemble typical food allergies, leading us to the diagnosis of FPIES.

While the journey can feel overwhelming, with time, patience, and support, you’ll find your way to a safe and healthy diet for your child.

Food Trials: Updated Information

Food trials for FPIES can be conducted at home or in a hospital, depending on the severity and type of reactions your child experiences. Here’s what you need to know:

1. Food Challenge in hospital
   • For acute reactions, food trials are often done in a hospital under strict medical supervision.
   • An IV line is typically placed as a precaution in case immediate intervention is needed.
   • Due to the delayed nature of some FPIES reactions, once a set observation period has passed without symptoms, the child may be sent home. Continued communication with your doctor is crucial during this time.
2. Food Challenge at home
   • In cases where your doctor feels it’s safe, trials may be conducted at home with clear instructions on what to monitor.
   • Always have an emergency plan in place, including easy access to the nearest ER.
3. New food trial process
   • Introduce new foods slowly and in small amounts. Starting with 1 teaspoon is common, gradually increasing the quantity if no reaction occurs.
   • Be prepared for setbacks. A failed trial can be discouraging, but each success is a significant milestone.
4. Emergency Preparedness
   • Always have essentials ready in case you need to rush to the ER.
   • The I-FPIES (formerly IAFFPE) provides a helpful emergency letter template. This letter explains FPIES reactions to ER staff and ensures your child gets the appropriate care.
   • Your doctor will provide an emergency letter upon diagnosis. Avoid using these templates if your child hasn’t been formally diagnosed, as the treatment plan may differ for other conditions.

By working closely with your healthcare team and being prepared, food trials can be a safe and productive way to expand your child’s diet.

Who Should Be Involved in Your Child’s Treatment

Managing FPIES typically requires a multidisciplinary team, as each child’s symptoms and needs can vary. Key members of your child’s care team may include:

• Pediatric Allergist: Essential for diagnosing and managing FPIES, including guiding safe food introductions.
• Pediatric Gastroenterologist: Addresses any gastrointestinal symptoms or complications.
• Dietitian/Nutritionist: Helps ensure your child is meeting their nutritional needs while navigating dietary restrictions.
• Pediatrician: Monitors your child’s overall health and coordinates care among specialists.

This team approach provides comprehensive support, ensuring your child’s health and well-being are managed effectively.

Learning to Accept Your Child’s FPIES Diagnosis

Finding out your child has Food Protein-Induced Enterocolitis Syndrome (FPIES) can feel overwhelming, but it’s important to remember: your child has a food allergy, not an infectious disease. They can play, laugh, and most importantly, live a healthy, happy, and normal life. While avoiding trigger foods is essential, once you identify their safe and unsafe foods, you’ll feel like you’ve crossed the finish line.

In the early days, I often worried, “How will we ever eat dinner as a family? What if she gets sick from something she eats?” But here’s the truth: we do eat dinner together. Her plate might look different, but we still gather as a family. And if she reacts to a new food, we add it to the list of triggers, avoid it, and move forward.

It’s natural to feel scared in the beginning. You’ll go through a range of emotions—anger, sadness, even feeling lost. But over time, acceptance comes. The best thing you can do is be your child’s advocate. Help them navigate this challenge, and know that while it may take time, it does get easier.

Most importantly, remember: you are not alone. There’s a community of parents and caregivers who understand what you’re going through, and together, we can support our children in leading full, joyful lives.

We’re beyond excited to be expanding our daughter’s diet! Every time we add a new food to her Safe Foods list, it feels like unwrapping a special gift on Christmas morning. Each success brings a sense of relief and joy that’s hard to describe.

I’m passionate about spreading awareness of FPIES, sharing our journey in hopes of helping other families who may be going through the same challenges. Together, we can make this path a little easier for everyone.

Disclaimer: This is not medical advice. The information shared here is based on our personal experience with FPIES. Please consult a medical professional for diagnosis and treatment specific to your child.

Sources

International Consensus Guidelines for the Diagnosis and Management of Food Protein-Induced Enterocolitis Syndrome (JACI)

International FPIES Association (I-FPIES)

Children’s Hospital of Philadelphia – FPIES

World Allergy Organization Journal – FPIES Guidelines Review

Journal of Allergy and Clinical Immunology: In Practice – FPIES Current Management Strategies