Longitudinal associations between youth tobacco and substance use in waves 1 and 2 of the Population Assessment of Tobacco and Health (PATH) Study.

•Any tobacco use predicted subsequent substance (alcohol or drug) use.•E-cigarette use predicted substance use except non-prescribed painkillers/sedatives.•Substance use consistently predicted tobacco use across products.•Marijuana use predicted use of all tobacco products except smokeless tobacco.•Targeting risk factors shared across tobacco and substances may be beneficial.