Diphenhydramine is a histamine H1-receptor antagonist that is commonly used for allergic reactions and frequently found in sleep aid products. A female in her 20s was brought to the emergency department with active tonic seizures after an intentional overdose of an over-the-counter drug containing diphenhydramine salicylate. Because the generalized tonic seizure continued for 52 min despite intravenous administration of diazepam, she underwent endotracheal intubation and continuous infusion of sedative agents, which terminated her seizures. Although her refractory status epilepticus was controlled using multiple antiepileptic medications, the state of severely impaired consciousness was prolonged, resulting in a vegetative state. While a literature search suggests that status epilepticus caused by diphenhydramine overdose is uncommon, special attention should be paid to this devastating neurological complication, and prompt medical management should be considered.
