Varenicline for the Treatment of Cannabis and Tobacco Use Disorders in Veterans

Inclusion Criteria: * Meet DSM-5 criteria for cannabis use disorder and use cannabis at least 3 days per week in the last 30 days. * Meet DSM-5 criteria for tobacco use disorder and smoke at least five cigarettes or report vaping 5 mg of nicotine daily. * Males and female Veterans aged 18 and over. * Be interested in quitting or reducing cannabis and tobacco use. * If female and of childbearing potential, must agree to use acceptable methods of birth control for the duration of the trial. * Must consent to random assignment, and be willing to commit to medication ingestion. * Must be able to read and provide informed consent. * Must have body weight \>110lbs (50kg) and have BMI between 18 and 35 kg/m2 * Must function at an intellectual level and have knowledge of the English language to sufficiently allow for accurate completion of assessments. Exclusion Criteria: * Women who are pregnant, nursing, or plan to become pregnant during the course of the study. * Individuals with severe renal impairment. * Lifetime history of DSM-5 Bipolar I or II Disorder, Schizophrenia or other psychotic disorder. Stably treated MDD, Dysthymia, GAD, Social Phobia, PTSD, and Specific Phobia diagnoses are acceptable (i.e. same dose of medication/psychotherapy has been prescribed for at least 2 months prior to screening and no changes in current medication/psychotherapy expected during course of the trial). * Suicidal ideation or behavior within the past 6 months. Subjects who are believed to be…