Isolated Oral and Esophageal Mucosal Injury as a Rare Oxcarbazepine Adverse Drug Reaction: A Case Report

Drug-induced mucosal injury may result from direct contact toxicity or immune-mediated adverse drug reactions.Although oxcarbazepine is a recognized etiology of severe hypersensitivity reactions, isolated oroesophageal mucosal injury without cutaneous or systemic involvement has not been previously described.We report a 68-year-old woman who developed severe diffuse esophagitis with concomitant oral mucosal ulceration approximately two weeks after oxcarbazepine initiation, with symptom onset within 24 hours of dose escalation from 150 to 300 mg twice daily.Histologic evaluation demonstrated predominantly lymphocytic esophageal inflammation with no evidence of infectious, eosinophilic, or immunobullous disease.The patient had no rash, peripheral eosinophilia, or systemic organ involvement.A Naranjo score of 7 supported a probable adverse drug reaction.Treatment consisted of discontinuation of oxcarbazepine alone, without the need for immunosuppressive or additional pharmacologic therapy.At five-month followup, the patient achieved endoscopic and histologic resolution.This case expands upon the recognized spectrum of oxcarbazepine-associated adverse drug reactions and emphasizes the importance of medication review in patients presenting with diffuse esophagitis and oral mucositis.