After alcohol intoxication, opioids are the most common cause of poisoning in patients presenting to North American emergency departments.1 Most opioids misused by patients originate from prescription medication. Most patients who overdose on prescription opioids are taking their medications differently than prescribed or are using opioids prescribed to someone else. These 2 main types of nonmedical opioid use represent a major cause of morbidity and mortality. Some individuals who misuse opioids are seeking euphoric effects, but others have developed dependence through chronic opioid use and are simply trying to avoid opioid withdrawal. Opioid-related harm has now reached epidemic levels: emergency department visits for nonmedical use of prescription opioids more than doubled from 2004 to 2011, accounting for an estimated 488 000 visits in 2011.1 Deaths have more than tripled since 1999, with an estimated 16 235 deaths attributable to prescription opioids in 2013.2,3