This post hoc analysis compared the safety of atomoxetine treatment of ADHD in adults with or without comorbid alcohol abuse/dependence. Study completion rates in patients receiving atomoxetine were comparable between heavy drinkers (60.9%) and patients with no alcohol-use disorder (71.0%) but lower in nonheavy drinkers (35.7%); however, there was no significant difference in discontinuation rates due to adverse events or lack of efficacy among these groups. Alcohol-use disorder patients, especially heavy drinkers, generally experienced the greatest frequency of treatment-emergent adverse events in both the atomoxetine and placebo groups. Vital signs and measures of hepatic function were not significantly different among the 3 drinking status groups taking atomoxetine.