Recognizing and Managing FPIES in Infants

At the 2026 American Academy of Allergy, Asthma & Immunology annual meeting, Anna Nowak-Wegrzyn, M.D., Ph.D., of NYU Grossman School of Medicine, shared important updates on how to recognize and manage food protein-induced enterocolitis syndrome (FPIES) in infants — a lesser-known type of food allergy that can be frightening but is often misunderstood.

FPIES typically appears in early infancy and most often presents as what experts call an acute reaction. Symptoms usually begin one to four hours after eating a trigger food, most commonly around the two-hour mark. Unlike classic food allergies, which often cause hives or breathing problems shortly after eating, FPIES reactions are delayed and primarily involve the digestive system. Babies may develop repetitive, forceful vomiting, sometimes described as projectile, along with pale skin, low energy and a floppy or lethargic appearance. In more severe cases, infants may be difficult to wake or appear very ill.

Because these symptoms can resemble a stomach virus, FPIES is often misdiagnosed, especially after a first episode. However, a key clue is the pattern: Symptoms recur after eating the same food and do not include fever, rash or typical allergy symptoms like itching or wheezing. Recognizing this pattern is critical for getting an accurate diagnosis.

Nowak-Wegrzyn emphasized that most cases (about 90%) are considered mild and can often be managed at home once families understand what to do. Treatment focuses on stopping vomiting and preventing dehydration. Parents are advised to give medications like ondansetron (if prescribed), followed by small, frequent sips of fluids such as oral rehydration solutions or breast milk. Severe cases, especially in children with a history of hospital visits, may still require emergency care and intravenous fluids.

Encouragingly, the long-term outlook for FPIES is generally positive. Many children outgrow the condition between ages 3 and 5, and for common triggers like milk, some may tolerate it even earlier. Researchers are also exploring ways to safely reintroduce foods, sometimes starting with baked forms (such as milk or egg in muffins), which may be better tolerated.

However, reintroduction must be approached carefully. Unlike other food allergies, there are no reliable blood or skin tests to guide timing, so decisions are made collaboratively between families and clinicians. In most cases, experts recommend waiting at least six months after a reaction before attempting reintroduction.

Increased awareness of FPIES can help families and clinicians recognize symptoms sooner, avoid unnecessary testing and manage reactions more confidently — leading to better outcomes for infants and their caregivers.