Opioid and benzodiazepine coprescribing leads to increased risk for medication adverse events. This interrupted time-series analysis demonstrated that a computerized provider order entry alert about opioid and benzodiazepine coprescribing led to decreases in coprescribing for high-risk patients compared to the time period before the alert was introduced and compared to a control site that did not receive the alert. The authors conclude that medication alerts can reduce high-risk prescribing practices.