Impact of cannabis legalization in the United States on trends in cannabis use and daily cannabis use among individuals who smoke cigarettes.
Cannabis legalization and increases in cannabis use are occurring rapidly in the United States (US). Cannabis and tobacco are often used together, but it is unclear whether cannabis legalization will differentially affect cannabis use among those using cigarettes. This study estimated changes from 2004 to 2017 in the prevalence of cannabis use and daily cannabis use by cigarette use status and examined whether state-level cannabis policy modified these trends. Public and restricted-use data from the 2004-2017 National Survey on Drug Use and Health were analyzed. Weighted logistic regressions were used to examine time trends in past-30-day cannabis use and daily caunabis use by cigarette use and cannabis law status from 2004 to 2017. Cannabis use and daily use increased significantly among those with and without cigarette smoking. Cannabis use and daily cannabis use were consistently 2-10x more common throughout this time among those with, versus without, cigarette smoking. In 2017, cannabis use and daily cannabis use were substantially more common among individuals who use cigarettes, and even greater among those who live in states where cannabis was legal for medical or recreational (i.e., non-medical) use. Cannabis use and daily cannabis use are increasing among US individuals who both smoke and do not smoke cigarettes. Cannabis and daily cannabis use are more common among those who smoke cigarettes and elevated even further among those residing in states that have legalized cannabis for recreational (i.e., non-medical) use. Tobacco control efforts should be adjusted to address increases in cannabis use among Americans who smoke cigarettes.