Patients with IgE mediated food Allergy have elevated risk of eosinophilic esophagitis, and new therapies like oral immunotherapy (OIT) carry additional risk of Eosinophilic Esophagitis (EoE). The goal of this study is to investigate the Esophageal String Test (EST) as a screening tool for Eosinophilic Esophagitis (EoE) during OIT therapy. Investigators will compare the efficacy of the Esophageal String Test to symptom assessment using a validated patient reported symptom questionnaire, the Pediatric Eosinophilic Esophagitis Symptom Score (PEESS) v2.0. Investigators will utilize these tools to screen patients at their baseline visit prior to the start of OIT, then at the 3- and 6-month OIT follow-up visits.

The goal of this study is to investigate the EST as a screening tool for EoE during OIT therapy. Investigators will utilize these tools to screen patients at their baseline visit prior to the start of OIT, then at the 3- and 6-month OIT follow-up visits.

The primary objectives are to assess feasibility of the EST as a screening tool for EoE in IgE mediated food allergy patients in an OIT program.

The secondary objective(s) are to: (1) estimate the correlation of EST and PEESS in screening for EoE in IgE mediated food allergy patients in an OIT program, (2) provide an estimate of the prevalence of EoE in IgE mediated food allergy patients, which Investigators will measure at the time of presentation for OIT, (3) provide an estimate of the incidence of development of EoE during the first 3- and 6- months of OIT.

The study will take place at the Children's Hospital of Philadelphia Food Allergy Clinic sites that participate in OIT. There will be 75 participants ages 7-18 years of age with IgE mediated food allergy who are undergoing oral immunotherapy for food allergies.

Inclusion Criteria:

An individual must meet all of the following criteria:

• Male or female, aged 7 to 18 years old, inclusive
• Have a history of Immunoglobulin (IgE)-mediated food allergy
• Considering using oral immunotherapy (OIT) for food allergies at CHOP°
• Able & willing to swallow the esophageal capsule
• Parental/guardian permission (informed consent) and if appropriate, child assent.
• Willing to comply with all study procedures and be available for the duration of the study.

Exclusion Criteria:

• Known or expected need for MRI imaging during the study period
• Known connective tissue disease
• Known eosinophilic disorder including any eosinophilic gastrointestinal disorder and hypereosinophilic disorder
• Past history of caustic ingestion or other esophageal injury
• History of esophageal surgery or dilation (i.e.: tracheoesophageal fistula repair)
• History of gastrointestinal motility disorder including esophageal achalasia
• History of inflammatory bowel disease
• Unwilling or unable to swallow the EST
• Oral or intravenous steroids in the preceding 60 days (not including swallowed topical fluticasone, budesonide, etc.)
• Participation in a clinical study that may interfere with participation in this study
• Pregnant or lactating females
• Limited English proficiency
• Parents/guardians or subjects who, in the opinion of the Investigator, may be non-compliant with study schedules or procedures.

Children 7 years of age or older with IgE mediated food allergy undergoing OIT at Children's Hospital of Philadelphia (CHOP) will be enrolled in this study. Prior work at CHOP and other pediatric centers has demonstrated that most children 7 years and older can swallow EST capsules.

Subjects will be identified by reviewing the Electronic Medical Record of IgE-mediated food allergy patients scheduled for evaluation in CHOP Allergy Clinic OIT clinic. Informed consent and assent will be obtained.

There is no plan to share individual participant data (IPD) available to other researchers.