New Study Sheds Light on FPIES, the Lesser-Known Food Allergy Affecting Young Children

A newly published study in the International Archives of Allergy and Immunology provides the first detailed look at Food Protein-Induced Enterocolitis Syndrome (FPIES) among Canadian children. Researchers established the country’s first FPIES registry and studied 87 children treated at the Montreal Children’s Hospital and affiliated clinics between November 2021 and April 2025. FPIES is a relatively little-known type of food allergy that primarily affects infants and young children and can cause severe vomiting, fatigue, and dehydration after eating a trigger food.

Unlike more familiar food allergies that can cause hives, swelling, breathing problems, or anaphylaxis within minutes, FPIES is a non-IgE-mediated food allergy that primarily affects the gastrointestinal system. Symptoms usually appear one to four hours after eating the problem food. “FPIES is an immune reaction that causes inflammation of the intestine and can lead to severe vomiting, severe fatigue and dehydration within a few hours of ingesting certain foods,” explained Dr Moshe Ben-Shoshan, senior author of the study and a pediatric allergist and immunologist at the Montreal Children’s Hospital. Because the symptoms can resemble a stomach virus, FPIES can be difficult to recognize and diagnose.

The study showed just how early FPIES typically develops. The median age at the time of a reaction was just seven months, and most reactions occurred before age two. Interestingly, 41% of reactions happened the first time a child was known to have eaten the trigger food, while 59% occurred after the food had previously been eaten intermittently. Although some reactions can be severe, nearly two-thirds of the children in the study were managed at home, while 36.8% were brought to a healthcare facility. Researchers classified 18% of reactions as severe.

Egg was the most common trigger, accounting for 27.6% of reactions, followed by shellfish at 21%, milk at 11.2%, fish and peanut at 10.3% each, oats at 7.1%, fruit at 6.2%, soy or other grains at 3.1%, and rice at 1%. About 9% of children reacted to more than one food. Allergic conditions were also common: 41.9% had eczema or atopic dermatitis, 20.4% had other food allergies, and 14% had asthma, while 36.6% had none of these associated conditions.

The outlook for many children with FPIES appears encouraging. Nearly one-quarter of participants underwent an oral food challenge within a year of their initial reaction to see whether they could tolerate their trigger food. Baked versions of the food were used in 70% of these challenges, particularly for foods such as egg and milk, and 81% of those challenged with baked forms were able to tolerate them. Follow-up also showed that many children eventually outgrew their FPIES. Of 32 children who tried eating their trigger food again during follow-up, 26 — or 81% — no longer experienced symptoms. “One of the most encouraging findings of our study is that the majority of children develop a tolerance to their trigger food over time and that the condition often resolves before they reach school age,” said first author Angela Mulé, an undergraduate student at McGill University.

Researchers say greater awareness of FPIES among doctors could help families avoid delays in diagnosis and unnecessary treatment. “An acute episode can be extremely distressing for parents. Without a clear diagnosis, many families make repeated visits to the emergency room before getting answers,” Ben-Shoshan said. He emphasized the importance of educating family physicians, pediatricians, emergency physicians, and other healthcare providers who may be among the first to see a child experiencing an FPIES reaction. Earlier recognition can help families understand which foods to avoid and how to respond if another reaction occurs.

The researchers now hope to expand their work beyond Quebec, enrolling children in other Canadian provinces to determine whether food triggers, treatment practices, and the course of FPIES differ across the country. They also hope to better understand how FPIES differs between children and adults. With the establishment of Canada’s first FPIES registry, researchers now have a foundation for learning more about a food allergy that remains poorly understood by many families — and even some healthcare providers.