Case Report of Lethal Concentrations of the Over-the-Counter Sleep Aids Diphenhydramine and Melatonin

Over-the-counter (OTC) medications are not typically considered “drugs of abuse” by the public, yet they are implicated in a portion of overdose cases. Although the toxicity of some OTC medications (such as acetaminophen, aspirin, and diphenhydramine [DPH]) has been extensively reported in the medical literature, the lethality of other substances (including melatonin) has not been well established. We report the case of a 21-year-old woman who was found deceased within her secure residence. Scene investigation revealed the presence of 5 empty containers of DPH and a partially empty container of melatonin, as well as a handwritten note of apparent suicidal nature. Upon autopsy examination, the gastric mucosa was notable for a green-blue discoloration, and the gastric contents were consisted of a green-tan viscous material with admixed blue particulate material. Further analysis revealed elevated concentrations of both DPH and melatonin within the blood and gastric contents. The death was certified as a suicide by acute combined DPH and melatonin toxicity. This paper will review the pharmacology of OTC sleep aid medications and provide a brief outline of their documented toxicity, in addition to reinforcing the role of death scene investigation and its correlation with autopsy findings.