Abstract
Diphenhydramine (DPH) is a commonly used over-the-counter drug. However, its widespread availability may contribute to severe and potentially fatal overdoses. DPH concentrations measured at multiple sampling sites have rarely been reported in fatal overdoses. This case report describes a fatal DPH overdose in a young woman whose blood DPH concentrations at multiple sampling sites exceeded the lethal range. DPH concentrations in blood and stomach contents enabled estimation of the amount of drug ingested, which was consistent with the investigative findings. Furthermore, the high DPH concentration in portal venous blood suggested that death occurred during the drug absorption phase. In fatal drug intoxication, measurement of drug concentrations at multiple sampling sites can provide complementary information for evaluating drug pharmacokinetics and the circumstances surrounding death.