82 randomized controlled trials including 22,619 patients with chronic non-cancer pain were included in this network meta-analysis investigating the relative benefits and harms of individual opioids in both extended-release (ER) and immediate-release (IR) formulations. Outcomes of interest included pain relief, function, and gastrointestinal adverse events (vomiting; constipation; nausea). Results of the network meta-analysis found that several opioids (i.e., ER codeine) provided superior pain relief and physical function vs. other opioids, but these estimates were limited by low certainty evidence. When looking at moderate-high certainty evidence only, no differences between opioids were observed and all increased the risk of gastrointestinal events compared to placebo, with no difference between individual opioids. Moreover, there were no observed differences in benefits or harms between ER and IR opioids.