An examination of consequences among college student drinkers on occasions involving alcohol-only, marijuana-only, or combined alcohol and marijuana use.

This event-level study examined within-person differences in consequences for college students who engaged in alcohol-only, marijuana-only, or simultaneous alcohol and marijuana (SAM) use across 18 weekend days. Participants ( = 451) were asked to report consequences they experienced on each occasion across five different types of events: (a) heavier alcohol combined with marijuana; (b) lighter alcohol combined with marijuana; (c) heavier alcohol only; (d) lighter alcohol only; and (e) marijuana only. Occasions involving heavy drinking, alone and in combination with marijuana, were associated with higher rates of consequences relative to lighter alcohol-only occasions, lighter alcohol combined with marijuana occasions, and marijuana-only occasions. Light alcohol-only occasions did not significantly differ on consequences from lighter alcohol combined with marijuana occasions or marijuana-only occasions. Past research has shown SAM use is associated with more consequences compared with alcohol-only use. The current findings suggest that SAM use is not necessarily riskier than drinking or using marijuana alone. Results suggested that on heavy drinking occasions, the number of consequences did not significantly change by also using marijuana. Findings suggest the benefit of targeted intervention strategies to reduce harms associated with heavy drinking occasions with and without SAM use. (PsycINFO Database Record (c) 2019 APA, all rights reserved).