Spinal, general, and epidural anesthesia have been implicated in the exacerbation of multiple sclerosis. However, to date, no attack has been reported following usage of mandibular block articaine anesthesia. This article describes the case of a 30-year-old man who presented with a sudden occurrence of diplopia on lateral gaze the day after extraction of the mandibular right second and third molars. Two times 1.8 mL 4% articaine solution with 1/100,000 adrenaline was used for local anesthesia. On neurological examination, a restriction on external gaze of his left eye was observed. Immunoglobulin G index was high, and oligoclonal band was present in spinal fluid evaluation. MRI revealed demyelinated plaques on the left side of the midpons, right cerebellar hemisphere, and bilateral white matter and supraventricular spaces. The left abducens palsy completely improved after treatment with intravenous methylprednisolone. Mandibular block articaine anesthesia may precipitate multiple sclerosis onset or attack. This case indicates that dental clinicians and neurologists may be alerted to isolated abducens palsy as a possible adverse effect of mandibular block articaine anesthesia. Keywords: anesthesia, articaine, isolated abducens nerve palsy, multiple sclerosis