The opioid epidemic, now in its second decade, is one of the most challenging public health crises in the US. Providing an effective response is complicated by multiple underlying causes and consequences as well as a misunderstanding of addiction and the medications used to treat it (1). Indeed, medications for opioid use disorder (MOUDs) are the most effective interventions for treating opioid addiction, but are not prescribed to many who would benefit. Here, we describe the distinction between physical dependence and addiction along with its implication for treatment, and discuss the mechanisms of action of MOUDs.