Eosinophilic Esophagitis (EOE) is diagnosed through a combination of medical history, symptom review, and specialized testing of the esophagus. Doctors first evaluate symptoms such as difficulty swallowing, food getting stuck, chest pain, persistent reflux-like symptoms, or feeding problems in children. Because EOE can mimic other digestive conditions, an upper endoscopy is usually required. During this procedure, a thin flexible camera is used to examine the esophagus for changes such as narrowing, rings, inflammation, or white patches. Even if the esophagus looks normal, tissue samples (biopsies) are taken because microscopic inflammation may still be present.

These biopsy samples are examined under a microscope to check for an increased number of eosinophils, a type of white blood cell that indicates allergic or immune-related inflammation in the esophagus. Additional testing, such as a barium swallow study, may be done to assess swallowing problems or structural narrowing. Allergy evaluations are sometimes recommended since EOE is closely linked to food allergies and immune responses. A gastroenterologist typically confirms the diagnosis, often working with allergy specialists to fully understand the condition. Early diagnosis is important to prevent long-term complications like scarring or narrowing of the esophagus and to help improve swallowing and overall digestive function.