BACKGROUND: Tobacco and cannabis are among the most widely used substances globally, and rates of co-use are on the rise. Understanding the impact of inhaled tobacco-cannabis co-use on health outcomes and tobacco cessation is critical for guiding patients and clinicians.

OBJECTIVES: To summarize the existing evidence, identify knowledge gaps, and prioritize research questions related to effects of inhaled tobacco-cannabis co-use on tobacco cessation and lung health.

METHODS: A multidisciplinary committee was convened to review the evidence, identify knowledge gaps, and develop research questions in four priority research areas: 1) common data elements and terminology; 2) patterns and prevalence of co-use; 3) impact of co-use on tobacco cessation; and 4) effects of co-use on lung health. A modified Delphi process was conducted in three rounds to reach consensus on prioritizing research questions.

RESULTS: The evidence reviewed by the expert panel in four priority research areas yielded the following gaps in the literature with high priority to address with future research: 1) lack of consensus on terminology and recommended co-use data elements; 2) limited research on co-use and tobacco-related disparities; 3) insufficient evidence on how cannabis use affects tobacco cessation; and 4) alarming yet inconsistent findings on the effects of co-use on lung health.

CONCLUSIONS: This statement outlines and guides a research agenda on the effects of inhaled tobacco-cannabis co-use on tobacco cessation and lung health. Consensus-driven recommendations include adopting harmonized terms and minimum data elements; studying the prevalence of co-use among populations experiencing tobacco-related disparities; evaluating the impact of co-use on tobacco cessation pharmacotherapies; and assessing the effects of co-use on the development and progression of lung diseases.