A 16-year-old female patient presented to the orthodontic department with a 2-week history of painful oral lesions that were affecting her ability to eat. Clinical examination revealed widespread oral ulceration, crusted bleeding from the lips with evidence of a herpes simplex infection in the region of the right buccal commissure. A diagnosis of oral erythema multiforme (EM) was made after a detailed clinical history and examination by the oral and maxillofacial team. Supportive care was provided alongside management with topical corticosteroids. Within 6 weeks of initial presentation, complete resolution of the lesions had occurred and the patient was able to resume active orthodontic treatment.