Accidental childhood death from diphenhydramine overdosage

A 15-month-old boy presented to an emergency department with tonic clonic jerking of all extremities and dancing eye movements. A history of instant coffee ingestion was obtained at that time. However, a routine blood analysis and toxicology screen showed a diphenhydramine level of 1.0 mg% (lethal, 0.5 mg%). Generalized tonic clonic seizures continued despite conventional therapy. A continuous thiopental infusion was used to control his seizure activity. This child never regained consciousness and was pronounced dead 7 days postingestion.