Participants
CUD, unstable medical/psychiatric disorder
DISORDER, DISORDERS
This study is being conducted at three sites across South Carolina. Participants are recruited from the community and must meet the following inclusion criteria: (1) ages 18–40; (2) daily cigarette smoker for ≥ 6 months, smoking ≥ 5 cigarettes per day; (3) must submit a breath carbon monoxide (CO) sample of ≥ 7 parts per million at screening; (4) interest in quitting smoking cigarettes (5+ on a 10-point scale); and 5) must be willing to take varenicline during the 12-week study. Additional inclusion criteria for the cannabis co-using sample include: (1) use of cannabis on at least 10 out of the past 30 days; and/or (2) positive qualitative urinary cannabinoid test at screening (limit of detection is 50 ng/ml). Quit interest for cannabis is not a requirement for inclusion. To be categorized as a tobacco-only control, participants are required to submit a negative qualitative urinary cannabinoid test at screening and self-report fewer than 10 days of cannabis use in the past 30 days.Participants are excluded from study participation under the following conditions: (1) any serious or unstable medical/psychiatric disorder (including severe substance use disorders, other than cannabis use disorder [CUD]) in the past 3 months that may interfere with study performance or affect safety; (2) currently pregnant or breastfeeding; (3) current use of medications with tobacco cessation efficacy; (4) use of any medications that would interfere with varenicline; or (5) regular use of tobacco or nicotine products other than combustible cigarettes. We do not exclude participants if they are using non-combustible methods of cannabis (e.g., wax, dabs, etc.).