Abuse of prescription opioids had reached epidemic levels and is responsible for increasing emergency department visits and overdose deaths. Most prescription opioid deaths involve at least one other drug, often a benzodiazepine (BZD). Up to 70% of opioid abusers also use BZDs, reportedly to enhance opioid-induced feelings of euphoria. Coabuse of opioids and BZDs increases the risk of physical dependence and overdose, and studies in humans suggest that BZD enhancement of abuse-related effects of opioids occurs in dependent, and not in nondependent, individuals.