Changes in Cigarette, E-Cigarette, and Cannabis Use among U.S. College Students Studying Abroad.

: Study abroad experiences among U.S. college students are risky environments for alcohol use; however little work has examined how studying abroad may affect other substance use. : This study assesses changes in frequency of cigarette, e-cigarette, and cannabis use among students studying abroad. : We recruited study abroad students from 63 institutions who studied in the 12 most popular destinations; 2,086 students completed surveys before leaving the U.S. and during their last month abroad. Descriptive and multivariate mixed-effects regression analysis compared substance use by location between students and country natives using publicly available data, identified behavioral and demographic predictors of frequency of substance use abroad, and estimated average adjusted prevalence of substance use by location. : Students' cigarette smoking increased three-fold while abroad; patterns of use varied significantly by location and mirrored smoking behaviors of native young adults. Rates of e-cigarette use declined while abroad and rates of cannabis use were similar abroad to pre-departure rates. However, cannabis use varied substantially by location and were higher than native peer rates. For all substances, most frequent substance use abroad was reported among males and those with prior histories of single drug and polydrug use. : Findings highlight the importance of continued research on drug use abroad among U.S. college students and pave the way for initial prevention and intervention efforts to target drug use abroad, particularly for cigarettes due to the negative health consequences of use and for cannabis given the potential legal ramification of use in non-legalized countries.