Postmortem diphenhydramine blood concentrations in children

Diphenhydramine has been available for decades in non-prescription formulations for the treatment of allergic reactions, insomnia and symptomology associated with colds. In addition, dimenhydrinate, a precursor to diphenhydramine, is available in preparations for the treatment of nausea and vomiting. Diphenhydramine and other first-generation antihistamines are being replaced by second- and third-generation antihistamines which are associated with fewer side effects, notably the lack of drowsiness; however, there are still a variety of therapeutic uses that have persisted in both adults and children. In this study, postmortem blood concentrations of diphenhydramine were determined, by liquid chromatography tandem mass spectrometry, in seven children with concentrations ranging from 0.051 to 2.6 mg/L. The cause of death in two cases was attributed, at least in part, to diphenhydramine toxicity while diphenhydramine detection in five cases was considered incidental to the cause of death.