Clinical characteristics of intentional overdose involving others' prescription medications: A retrospective observational study

Background: Intentional drug overdose is a common method of self-harm, typically involving an individual’s own prescription or over-the-counter medications in Japan. However, a subset of patients uses medications prescribed to others, raising concerns regarding medication misuse, unauthorized access, and public health implications. While international studies report that 36.7–62% of overdoses involve non-prescribed medications, the corresponding rate in Japan appears to be lower. This study aimed to examine the clinical characteristics and outcomes of overdose patients who used medications prescribed to others, based on cases encountered at a tertiary emergency medical center. Results: This retrospective observational study included 444 patients treated for intentional prescription drug overdose at a tertiary emergency medical center in Japan over a seven-year period. Of these, 25 patients (6%) had used medications prescribed to others. Compared to those who used their own prescriptions, patients in the non-prescribed group were significantly less likely to have a history of psychiatric consultation (3% vs. 77%). Clinical presentations and vital signs were largely similar between the groups. Benzodiazepines were the most commonly involved drug class in both groups (39%). Conclusions: A small but significant proportion of overdose patients used medications prescribed to others, representing a high-risk group typically disconnected from psychiatric care. These findings highlight the need for stricter prescription oversight, improved household medication control, and early identification and intervention for individuals lacking psychiatric support. Multifaceted public health efforts—including suicide prevention strategies—are essential to mitigate the risk of such overdoses.