Flavored E-Cigarette Sales Restrictions and Young Adult Tobacco Use.

Importance: More than one-quarter of US residents live in states or localities that restrict sales of flavored electronic nicotine delivery systems (ENDS), often as a means to reduce youth vaping. Yet, how these policies affect young adult vaping and smoking remains unclear. Objective: To estimate the effects of ENDS flavor restrictions on ENDS use and cigarette smoking among young adults (age 18-29 years) in the US. Design, Participants, and Setting: This quasi-experimental analysis used annual survey data from the 2016 to 2023 Behavioral Risk Factor Surveillance System (BRFSS), a series of nationally- and state-representative, repeated cross-sectional surveys of noninstitutionalized civilian adults in the US. Two-way fixed-effects specifications were estimated to assess how ENDS flavor restrictions affect young adults' use of ENDS and cigarettes. Analyses were adjusted for potential confounders including concurrent tobacco control policies, respondent demographic characteristics, and socioeconomic factors. Data analyses were conducted in November 2023 and repeated in October 2024 to incorporate newly released 2023 survey data. Main Outcomes and Measures: Current and daily use of ENDS and of cigarettes as measured in the BRFSS. Results: Balanced panel analyses of 242 154 individuals aged 18 to 29 years consistently found that state ENDS flavor restrictions were associated with statistically significant reductions in daily vaping and increases in daily cigarette smoking. Estimates were similar across robustness checks, with the main specification showing 3.6 (95% CI, -5.0 to -2.1) percentage point (ppt) reductions in daily vaping and 2.2 ppt increases in daily cigarette smoking (95% CI, 1.0 to 3.4) relative to changes in states without restrictions. These estimates are equivalent to an 80% reduction in daily vaping and 22% increase in daily smoking compared with 2018 mean rates. Conclusions and Relevance: The findings of this quasi-experimental analysis of BRFSS survey data indicate that state restrictions on flavored ENDS sales were associated with reduced vaping among young adults but may have unintentionally increased cigarette smoking, potentially offsetting public health gains. These findings suggest that alleviating the burden of tobacco-related disease will require regulatory strategies that balance reducing vaping with preventing increases in more lethal, combustible tobacco use.