Patterns in methods, timing, and sequence of nicotine and cannabis co-use among adolescents

SIGNIFICANCE: Adolescent co-use of nicotine and cannabis increases their negative health risks. Much is still unknown about what products adolescents co-use, when, and how. METHODS: We collected a cross-sectional, self-report survey (N = 4760) in Spring 2024 across eight Connecticut high schools (M=15.86 years, 51% female, 60% White, 38% Hispanic, 22% Black, 81% straight, 10% bisexual, 4% gay/lesbian). We assessed co-use timing (i.e., same-occasion, same-day, different-day); same-occasion sequence (i.e., simultaneous, cannabis/nicotine first); nicotine and cannabis products used for same-month co-use; and methods of simultaneous co-use (e.g., blunts, spliffs). We used Chi-squared tests to examine differences in same-month, same-occasion, and simultaneous co-use rates by race, ethnicity, sex, and orientation. RESULTS: Youth who ever used nicotine and cannabis (n = 885) reported same-occasion co-use (83%), different-day co-use (45%), and same-day different-occasion co-use (41%). Same-month co-use differed by race, ethnicity and sexual orientation. Same-occasion co-use differed by race. Among youth reporting lifetime same-occasion co-use (n = 731), 34% used cannabis before nicotine, 31% nicotine before cannabis, and 96% both substances simultaneously. Simultaneous co-use differed by race and ethnicity. Among adolescents with same-month co-use (n = 397), the most endorsed nicotine products were e-cigarettes (74%), nicotine pouches (16%), and cigarettes (13%), with cannabis use by smoking (35%) or vaping (15%) flower and vaping concentrates (25%). The most common methods for simultaneous co-use were blunts, using two products simultaneously, and spliffs. CONCLUSION: Results indicate a range of co-use behaviors, with elevated risk based on race, ethnicity, and sexual orientation. Identified co-use patterns should be examined for impacts on addiction risk and health harms.