OBJECTIVES Cannabis use is associated with suicide risk in the general population; however, it is unknown if this association is also present in patients with opioid use disorder (OUD). The purpose of this study is to investigate the association between cannabis use and suicidal ideation in patients with OUD.

METHODS We conducted a multivariable logistic regression analysis to assess the association between cannabis use and suicidal ideation, amongst a large cohort of patients with OUD. Current cannabis use and suicidal ideation over the past 30 days were obtained by self-report.

RESULTS Cross-sectional data from 2335 participants with OUD were included in the analysis, of whom 51% report current cannabis use. We found a positive association between cannabis use and suicidal ideation (OR = 1.41, 95% CI 1.11, 1.80, P = 0.005). We found that men (OR = 1.84, 95% CI 1.44, 2.35, P < 0.001), younger individuals (OR = 1.02, 95% CI 1.01, 1.03), P = 0.004), and that those with more symptoms of anxiety or depression (OR = 1.16, 95% CI 1.15, 1.18, P < 0.001) were more likely to report suicidal ideation.

CONCLUSIONS Cannabis use is associated with a heightened propensity for suicidal ideation amongst patients with OUD, who are already a high-risk population. Further research into the potential harms of cannabis use in this population is required given the prevalence of its use and potential benefits in mitigating opioid withdrawal.