Young adults’ simultaneous use of alcohol and marijuana linked to more negative consequences

Up to one in four young adults use alcohol and marijuana simultaneously (i.e., use at the same time with overlapping effects), a behavior linked to a greater risk of adverse consequences. Given the expanding legalization of non-medical marijuana use, there is an urgent need to better understand the effects of simultaneous use and who is most vulnerable to adverse outcomes. Previous research has yielded mixed and limited results.