Simultaneous use of alcohol, cannabis, and energy drinks predicts increased daily alcohol consumption and alcohol consequences.

Simultaneous alcohol and cannabis (SAM) use and alcohol mixed with energy drinks (AmED) days are associated with heavier drinking and negative consequences compared to alcohol-only days. However, it remains unclear if SAM and AmED days differ from one another in terms of consumption and negative consequences. It also remains unclear how often days characterized by both SAM + AmED occur and if these days are associated with incremental risk for heavier drinking and negative consequences. College students who engage in SAM use and AmED completed a 30-day timeline followback interview. Day-level data on drinking days were curated to test whether days characterized by alcohol only, SAM use only, AmED use only, or SAM + AmED were associated with increased drinking quantity, negative alcohol consequences, and positive alcohol consequences. Twenty-one percent of drinking days were AmED days, 19% were SAM days, and 15.4% were SAM + AmED days. SAM-only, AmED-only, and SAM + AmED days were associated with increased drinking and negative consequences compared to alcohol-only days. However, SAM-only and SAM + AmED (but not AmED-only) days were associated with more positive consequences than alcohol-only days. SAM-only and AmED-only days did not differ in drinking quantity or consequences, whereas SAM + AmED days were associated with increased drinking and negative (but not positive) consequences compared to both SAM-only and AmED-only days. Combined SAM + AmED days are common and associated with increased risk for negative outcomes. Prevention efforts should consider how to reduce the occurrence of SAM + AmED use and how to reduce risk on days when it does occur. (PsycInfo Database Record (c) 2025 APA, all rights reserved).