Diphenhydramine Overdose: A Case Report and Topic Review of Prehospital Diagnosis and Treatment

Diphenhydramine (DPH), a readily available first-generation H1 receptor antihistamine, can have severe consequences when taken in excessive amounts and can lead to grave outcomes such as seizures, dysrhythmias, coma, and death. Recognizing the early signs and symptoms of DPH toxicity is crucial. Fortunately, fatal adult cases of DPH overdose are rare. This report describes a near-fatal overdose of a young adult female who experienced recurrent seizures, respiratory failure, and cardiac arrest with the return of spontaneous circulation (ROSC) in the prehospital setting and complete functional recovery. This case underscores the urgency of addressing DPH toxicity and the utility of reversal agents, such as sodium bicarbonate, in sodium channel blockade.