Rates and correlates of simultaneous use and mixing of alcohol, tobacco, and cannabis among adults who currently use alcohol and tobacco

Background: Little research exists on simultaneous use of multiple substances that pose additive risk for negative health outcomes. We examine rates and sociodemographic and state cannabis legalization status correlates of simultaneous use (i.e., use > 1 substance on the same occasion) and mixing (e.g., co-administration of substances) of tobacco, alcohol, and cannabis among a U.S sample of adults who currently use alcohol and combustible tobacco products. Methods: Using a survey panel, we recruited 1,300 U.S. adults who reported past 30-day use of alcohol and combustible tobacco between June to July 2021. We fit logistic regression models to examine associations between sociodemographic characteristics and cannabis legalization status with use of alcohol, tobacco, and cannabis. Results: The majority (67%) of participants reported simultaneous alcohol and tobacco use. Over half (55.5%) of tobacco and alcohol co-users reported past 30-day cannabis use, 42.1% reported simultaneous tobacco and cannabis use, and 45% reported mixing tobacco and cannabis in the form of a blunt. Additionally, 36.5% reported simultaneous alcohol and cannabis use, and 33.1% reported simultaneous alcohol and blunt use. Age, race, gender, and income level were associated with simultaneous use of some substances. State cannabis legalization status was not significantly associated with outcomes. Conclusions: Overall, the prevalence of simultaneous use was high among this U.S. purposive sample of adults who reported current co-use of alcohol and tobacco products. Researchers should consider measuring simultaneous use of substances in samples of co-users, which may inform the efficacy of interventions focused on cessation or harm reduction of substance use.