When seven-month-old Lily started throwing up violently a few hours after eating eggs, her parents rushed her to the emergency room — twice — before anyone could tell them what was wrong. The vomiting, the exhaustion, the dehydration — it all looked like a severe stomach bug. But it wasn't a bug at all. It was FPIES, a confusing food allergy that confuses doctors as often as it terrifies parents.
FPIES stands for Food Protein-Induced Enterocolitis Syndrome. It's an immune reaction that inflames the intestine and can cause severe vomiting, fatigue and dehydration within a few hours of eating certain foods. Unlike typical food allergies that cause reactions within minutes — think hives, swelling, trouble breathing — FPIES symptoms show up one to four hours later, often looking exactly like gastroenteritis, or stomach flu. That makes it incredibly hard for doctors to catch.
"An acute episode can be extremely distressing for parents," says Dr. Moshe Ben-Shoshan, a pediatric allergist at the Montreal Children's Hospital. "Without a clear diagnosis, many families make repeated visits to the emergency room before getting answers."
Now, a new study from McGill University is helping bring those answers faster. Researchers at the Research Institute of the McGill University Health Centre tracked 87 children, ages one month to 13 years, at the Montreal Children's Hospital. It's the first Canadian study to focus specifically on FPIES, and its findings are genuinely reassuring.
The study found that eggs triggered the most reactions (27.6%), followed by seafood (21%), milk (11.2%), fish (10.3%), and peanuts (10.3%). About 9% of children reacted to more than one food. Most symptoms started around seven months of age and occurred before age two.
But here's the part that matters most: more than 80% of the children in the study no longer had symptoms in the years after their diagnosis. Most outgrew the allergy before starting school.
"One of the most encouraging findings is that the majority of children develop a tolerance to their trigger food over time," says Angela Mulé, the study's first author and an undergraduate student at McGill. Without a diagnosis, children with FPIES often end up on unnecessary restricted diets, which can lead to nutritional problems during crucial growth years.
The researchers are now planning to expand their work to other Canadian provinces to compare how FPIES shows up across different regions. They also hope to study whether adults can develop this condition, which remains largely unknown in adult medicine.