Background <p>Although the goal of opioid agonist therapy is typically understood by clinicians to be the cessation of the use of non-prescribed opioids, many people taking opioid agonist therapy continue to use other opioids. The purpose of this study was to explore how people who use both prescribed opioid agonist therapy and non-prescribed opioids understand their use of both agents.</p> Methods <p>An interpretative phenomenological analysis was conducted with ten participants recruited from harm reduction sites in Toronto who were concurrently using opioid agonist therapy and non-prescribed opioids. Semi-structured interviews were audio-recorded and transcribed verbatim. Data were analysed to explore participants’ understanding of their use of both opioid agonist therapy and non-prescribed opioids.</p> Results <p>Participants had unique reasons for the use of opioid agonist therapy and non-prescribed opioids; while opioid agonist therapy is free, relatively safe, and helps control opioid withdrawal symptoms, non-prescribed opioids satisfy opioid cravings, ease physical and emotional pain, and can be used with more autonomy. The participants’ relationships with different opioids are complicated, and some struggle to reconcile their use with their goals.</p> Conclusions <p>Participants shared that opioid agonist therapy and non-prescribed opioids fill complementary roles in their lives, each presenting their own benefits and challenges. Their experiences highlight opportunities for improving the provision of opioid agonist therapy in order to make it more effective and acceptable for people who use non-prescribed opioids, which is a crucial strategy in combatting mortality from the opioid toxicity crisis. Opioid agonist therapy can thus be situated within the harm reduction continuum as a practice that can be beneficial whether or not it results in abstinence, and clinicians should offer tailored regimens that take patient preferences and goals into account.</p>