Question: How does the risk of overdose change with the number of days with concurrent opioid and benzodiazepine use?

Findings: In this cohort study of US Medicare data, the overdose risk associated with concurrent benzodiazepine use changed over time. Concurrent benzodiazepine use was associated with a 5-fold increase in the risk of opioid-related overdose during the initial 90 days and an increase of 1.87 times on days 91 to 180.

Meaning: Policy interventions should focus on preventing concurrent opioid and benzodiazepine use in the first place instead of reducing the length of concurrent use. Patients using both medications should be closely monitored, particularly during the first days of concurrent use.