Objective: To examine the impact of flavour, device type and health warning messages on youth preference for electronic nicotine delivery systems (ENDS), and to provide evidence and data to inform the Food and Drug Administration’s potential regulatory actions on ENDS.

Design: An online discrete choice experiment was conducted in September 2015. Each participant was given nine choice sets and asked to choose one out of two alternative ENDS products, with varying characteristics in three attributes (flavour, device type and warning message). The impact of the attributes on the probability of choosing ENDS was analysed using conditional and nested logit regressions, controlling for individual sociodemographic characteristics and current smoking status.

Setting and participants: A general population sample of 515 participants (50 ever-users and 465 never-users of ENDS) aged 14–17 years were recruited to complete the experiment using an online panel.

Results: Fruit/sweets/beverage flavours significantly increase the probability of choosing ENDS among youth (p<0.01 for never-users and <0.1 for ever-users) and flavour has the most pronounced impact among three attributes. Among never-users, menthol flavour also increases (p<0.05) the probability of choosing ENDS compared with tobacco flavour. Vaping devices that are modifiable, compared with cigarette-like e-cigarettes, increase (p<0.05) the probability of choosing ENDS among adolescent never-users. Warning messages reduce (p<0.01) the probability of choosing ENDS among never-users.

Conclusions and relevance: Restricting fruit/sweets/beverage flavours in ENDS, regulating modifiable vaping devices and adopting strong health warning messages may reduce the uptake of ENDS among youth.