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.