OFC Updates for FPIES in Infants, With Anna Nowak-Wegrzyn, MD, PhD

At the 2026 American Academy of Allergy, Asthma & Immunology (AAAAI) annual meeting in Philadelphia, Anna Nowak-Wegrzyn, MD, PhD, of NYU Grossman School of Medicine, presented updates on the diagnosis and management of food protein–induced enterocolitis syndrome (FPIES) in infants. Updates included efforts to refine oral food challenge (OFC) protocols and improve recognition of the condition in early life.

HCPLive spoke with Nowak‑Wegrzyn during the meeting to discuss key takeaways from her session. She emphasized that despite growing clinical awareness, the condition remains fundamentally a clinical diagnosis.

“We didn't have any kind of diagnostic breakthroughs,” Nowak‑Wegrzyn said. “It’s still a clinical diagnosis, so the clinician has to be familiar with the manifestations, with the symptoms to make a diagnosis, because there's no blood test, there’s no skin test that can confirm it.”

FPIES is a non–immunoglobulin E–mediated food allergy that typically presents in infancy with delayed gastrointestinal symptoms following ingestion of a trigger food. Unlike classic immunoglobulin E–mediated food allergies, which can often be identified through skin prick testing or serum immunoglobulin E measurement, most patients with FPIES have negative results on standard allergy testing. However, a subset of patients may develop positive immunoglobulin E tests to the triggering food, a presentation sometimes described as atypical disease.

Clinically, the syndrome is characterized by delayed onset vomiting, typically occurring 1–4 hours after ingestion of the offending food. Infants may also appear pale or lethargic and can develop decreased muscle tone during episodes, symptoms that can initially resemble other serious conditions.

Because of this presentation, physicians must often consider infectious etiologies during the initial evaluation. Sepsis and viral gastroenteritis are common conditions included in the differential diagnosis.

The overlap in clinical presentation can also extend to laboratory findings. Infants experiencing a reaction may demonstrate elevated white blood cell counts with a predominance of neutrophils, a pattern that can mimic infection and complicate early diagnosis. However, symptom resolution patterns can help distinguish FPIES from infectious illnesses.

“Unlike with sepsis or viral gastroenteritis, infants have symptoms that resolve quite quickly,” Nowak-Wegrzyn said. “If they are not being fed the food, then within several hours, they…start going back to baseline. “Obviously, you have to do all of the workup right…you have to rule out infections, and only after the fact, when you know there's resolution of symptoms, there's negative tests for infectious causes, then you can conclude that this was likely food protein-induced enterocolitis syndrome reaction.”

Diagnosis becomes clearer if a child later experiences a similar reaction after re-exposure to the same food. Typically, infants remain healthy between episodes and demonstrate normal growth and development, with symptoms appearing only when the trigger food is ingested.

Beyond diagnosis, Nowak-Wegrzyn highlighted evolving recommendations regarding OFCs.

“We are changing the protocol to involve only a partial surveying of the food,” Nowak-Wegrzyn said. “We're simplifying that approach [of] the food challenge, providing guidance [on] what is the age-appropriate serving size of the most common foods like milk, egg, oat, wheat, rice, peanut… just to make it to facilitate introduction of foods.”

References

Nowak-Wegrzyn, A. Update on Diagnosis and Management of FPIES in Early Life. Session presented at AAAAI 2026 in Philadelphia on February 27, 2026.