Children who outgrow one type of food allergy may develop a more severe and persistent type of allergy to the same food, experts say.
They suggest that physicians and parents carefully monitor children with food allergies to recognise early signs of eosinophilic esophagitis (EoE) - a severe and often painful allergy that has been increasing in recent years.
"These two types of allergy have some elements in common, but patients with EoE usually do not go on to develop tolerance to the foods that trigger EoE," said paediatric allergist Jonathan M. Spergel from Children's Hospital of Philadelphia.
EoE involves swelling and inflammation of the esophagus. Often painful, EoE may cause weight loss, vomiting, heartburn and swallowing difficulties.
It can affect any age group, but is often discovered first in children experiencing feeding difficulties and failure to thrive.
The researchers team compared EoE with IgE-mediated food allergy - the more familiar type of food allergy.
Nuts, eggs or milk, for example, may trigger hives, other skin reactions, vomiting or other symptoms.
The researchers performed a retrospective analysis of 1,375 children for EoE between 2000-12.
Of that number, 425 children could be shown to have a definite food causing their condition - most commonly milk, egg, soy and wheat.
Within that subgroup, 17 patients had developed EoE to a food after having outgrown IgE-mediated allergy to that specific food.
"The pattern we found in those 17 patients suggests that the two types of food allergy operate by different mechanisms and cause different functional changes," Spergel said.
"However, this pattern also raises the possibility that prior IgE-mediated food allergy may predispose a patient to developing EoE to the same food."
According to the research, patients who undergo desensitisation therapy for IgE-mediated foods allergies subsequently develop EoE to the same food - a fact that physicians should consider in managing care for patients with food allergies.
In desensitisation therapy, a clinician exposes a patient to miniscule amount of an allergy-producing food, then gradually increases the amount - aiming for the patient to become tolerant to that food.
The findings were shared at the annual meeting of the American Academy of Allergy, Asthma and Immunology in San Diego.
