Deaths Due to Diphenhydramine

This is the authors' abstract. We don't add key points for this paper.

Diphenhydramine (DPH) is an antihistamine available in many over-the-counter (OTC) products, particularly sleep-aids, and some prescription preparations. The number of reported poisonings and deaths have increased since the early 1980's. Sixteen fatalities occurred in Ontario from 1984–87 (eight additional cases from 1982–83 were reviewed). All were suicidal ingestions and the age range was 17–81 years (mean age 35 yrs). DPH was the only CNS depressant ingested (monoingestions) in four cases, all showing post mortem blood concentrations above the potentially fatal concentration (0.50 mg/100 mL). The remaining deaths involved DPH combined with ethanol and/or CNS depressant drugs and, compared to the monoingestion group, the average and minimum fatal DPH concentrations were lower. Five of these cases were at or below 0.50 mg/100 mL (range 0. 21–0.50 mg/100 mL). They were older than the average individuals and had significant cardiac disease. Sleep-aids dominated in the DPH deaths studied. Investigators should be aware of the possible role of DPH in suicidal and unexplained deaths.