Varenicline In-Patient Study

Inclusion Criteria: * The sample, 40 women and 40 men, will be hospitalized patients recruited from Stanford Hospital and Clinics who report smoking at least 10 cigarettes per day prior to hospitalization, have confirmed tobacco use by cotinine testing, and an expected hospitalization of at least 3 days duration from the date of study enrollment. Intention to quit smoking will not be required for study participation. Exclusion Criteria: \- Study exclusion criteria are: dementia or other brain injury precluding ability to participate; Alzheimer's Disease; Parkinson's Disease; Huntington's Disease; meningitis; seizure disorder of a sustained nature; delirium; brain surgery; drug and/or alcohol dependence; suicidal ideation; end-stage renal disease (i.e., on dialysis); hypertensive crisis; stroke; myocardial infarction (MI) with severe cardiac damage; pregnancy or breastfeeding; non-English speaking; complete homelessness; or currently engaged in tobacco treatment. Study staff will consult with clinical staff prior to approach for study enrollment. In cases of severe renal impairment (estimated creatinine clearance \<30 mL/min), medical staff will consult with participants' physician to assess the appropriateness for study enrollment.