BackgroundMultiple tobacco and e-cigarette product (MTEP) use, the concurrent use of two or more different types of tobacco and/or e-cigarettes products, is common among young people in the US. Changes in patterns of MTEP use among US youth between 2014 and 2020 were identified and the determinants of MTEP use were examined.MethodsFour years of repeated cross-sectional data from the US National Youth Tobacco Survey of middle and high school students from grade 6 to 12 (N_total=77 402). Multigroup latent class analysis (LCA) was applied to the data series to allow for simultaneous identification of MTEP use patterns between 2014 and 2020. Logistic regression was used to predict class membership on demographic and tobacco-related variables.FindingsOver the 7-year period, LCA identified three patterns: minimal/non-users (MNU: ~89.8%), mostly occasional e-cigarette and cigarette users (MOEC: ~9%) and polytobacco users (POLY: ~1.2%). From 2014 to 2020, MNU increased from 86.4% to 92% (p<0.05), while MOEC and POLY decreased from 11.2% to 7.9% and from 2.4% to 0.1%, respectively. The probability of regular e-cigarette use increased from 0 to 2.3% among MNU, 6% to 31.9% among MOEC and 29.6% to 67.6% among POLY (p<0.05). In binomial logistic regression, being male, in high school, non-heterosexual, living with someone who uses tobacco at home, having cognitive difficulties, having lower perceptions of tobacco’s danger and exposure to tobacco marketing were associated with greater odds of MOEC and POLY than MNU.ConclusionsThere was an increase in regular e-cigarette use in all three classes, but a corresponding decrease in the proportion of MTEP use. Public health interventions to discourage uptake of e-cigarettes, such as tighter restrictions on marketing to minors, are warranted and there is a need to consider disparities in the determinants of MTEP use.