It is estimated that 20-30% of young adults engage in simultaneous alcohol and cannabis use. Simultaneous use of cannabis and alcohol is associated with heavier consumption than single-substance use. In addition, simultaneous use has been implicated in more social consequences, mental health problems, and dependence symptoms than single substance use. However, these results have been mixed depending on whether the single substance was alcohol or cannabis. This study examines within-person differences on alcohol-only, cannabis-only, and simultaneous use days in the experience of seven specific acute negative consequences.  

The study’s sample consisted of 341 college students from three state universities who were co-users of alcohol and cannabis. Participants completed 56 days of five daily surveys across two bursts. During each survey participants were asked to report the type of substance used that day (alcohol, cannabis, both, or neither). Respondents were also asked to report the amount of alcohol and/or cannabis consumed on each occasion. The morning after alcohol and/or cannabis consumption participants were asked about seven consequences: hangover, nausea/vomiting, injury, driving drunk/high, blackout, rude/aggressive behavior, and unwanted sex. Data was analyzed using a series of generalized linear mixed effects models.  

Results of the data analysis showed 83.3% of participants reported at least one co-use day. Compared to alcohol-only days, on cannabis-only days students were significantly less likely to report any of the negative consequences except for driving high/drunk. Participants were more likely to report hangover and less likely to report driving high/drunk on alcohol-only days when compared to co-use days. Greater consumption of alcohol increased the rate of endorsing all of the negative consequences except driving high/drunk. When comparing cannabis-only and co-use days, students were less likely to endorse all of the consequences except driving high/drunk and unwanted sex on cannabis only days. Greater cannabis consumption was correlated with a higher rates of driving high/drunk.  

Takeaway: Among college students negative consequences experienced following substance use may differ depending on if alcohol, cannabis, or both substances are consumed. 

Drohan, M.M., Stevens, A.K., Gunn, R.L., Sokolovsky, A.W., White, H.R., Jackson, K.M.. Acute Consequences Associated with Co-use of Alcohol and Cannabis: A Daily Survey Analysis. Journal of Studies on Alcohol and Drugs. 2022;jsad-22. Doi: 10.15288/jsad.22-00062