Electronic cigarettes (e-cigarettes) are the most used nicotine/tobacco product among young people in the United States (US) (Birdsey et al., 2023). According to the US national reports (Boakye et al., 2022; Cornelius et al., 2021; Dai and Leventhal, 2019), young adults have the highest prevalence of e-cigarette use among all adult age groups. In 2021, around 11% of young adults aged 18–24 years reported using e-cigarettes every day or some days (Cornelius et al., 2021). E-cigarette use in young adults may lead to adverse health effects, such as respiratory conditions (Asfar et al., 2022; Lødrup Carlsen et al., 2018). Additionally, e-cigarettes deliver nicotine, which can result in dependence (Vogel et al., 2018) and potentially cause damage to the developing brain (Castro et al., 2023).

The Family Smoking Prevention and Tobacco Control Act gives the US Food and Drug Administration (FDA) the authority to regulate tobacco-derived nicotine (TDN) e-cigarettes (FDA, 2016). Recently, tobacco manufacturers introduced tobacco products containing synthetic or non-tobacco nicotine (NTN), which is chemically synthesized in a laboratory rather than derived from tobacco (Jordt, 2021). The most common NTN products are seen among e-liquids for refilling cartridges (e.g., Vape Dinner Lady), and disposable e-cigarettes (e.g., Puff Bar; Jordt, 2021; Morean et al., 2022a), and nicotine pouches (e.g., Juice Head). For example, in 2021, Puff Bar, a manufacturer of disposable e-cigarettes introduced a new product line with e-cigarettes containing NTN (Jordt, 2021). These novel products initially enabled manufacturers to circumvent FDA regulations on TDN products, leading to a rapid rise in popularity (Jordt, 2021). These manufacturers also took the opportunity to alter their marketing strategies to appeal to the public, which included introducing terms like “tobacco-free nicotine” (TFN) (Jordt, 2021; Truth initiative, 2023) and launching marketing materials that highlighted the benefits of NTN products, such as positioning NTN e-cigarettes as healthier alternatives with superior taste compared to traditional e-cigarettes (Chen-Sankey et al., 2021). While the FDA clarified their regulatory authority over NTN in 2022 (FDA, 2022), these products remain readily available and popular in the commercial market. Thus, more research is needed to understand how these products appeal to young people to inform NTN regulations.

One reason young adults use e-cigarettes is the presence of a wide variety of flavors (Goldenson et al., 2019; Krishnan-Sarin et al., 2017; Leventhal and Dai, 2021). Sweet flavors, such as fruit, candy, and dessert, provide a pleasant taste and smell, enhance the enjoyment of e-cigarette use (Kim et al., 2016), increase the reinforcing effects of nicotine (Kroemer et al., 2018), and contribute to a higher likelihood of experimentation and continued use among young adults (Landry et al., 2019). The cooling agents in mint and menthol e-cigarette flavors, which reduce the harshness and irritation of nicotine (Krishnan-Sarin et al., 2017; Rosbrook and Green, 2016), likely contribute to the popularity of mint and menthol-flavored e-cigarette use among young adults (Chaffee et al., 2022; Clausen et al., 2022; McCauley et al., 2022). Taken together, these findings underscore the importance of flavors being a principal target of e-cigarette product regulations to reduce use among young people.

In 2020, the US FDA enforced restrictions on unauthorized flavored e-cigarette cartridges but continued to allow tobacco and menthol flavors (but not mint) (FDA, 2020). However, this enforcement decision did not include flavors used in disposable e-cigarettes or bottled e-liquids for refilling open-system e-cigarettes. Consequently, flavored disposable e-cigarettes and refilling cartridges have remained prevalent among young people (Birdsey et al., 2023; Gaiha et al., 2022; Leventhal et al., 2022; McCauley et al., 2022). For instance, a national survey found that a vast majority of US youth are using flavored disposable e-cigarettes and pod/cartridge-based products, with mint and menthol flavors as the most popular choices, and past-month use of flavored disposables surpassing pod-based e-cigarettes in 2021 (Gaiha et al., 2022). This prevalence could be attributed to the advantages of disposable e-cigarettes, which are novel, less expensive, and more convenient to use than non-disposable products, thus appealing to a broad spectrum of young customers (Leventhal et al., 2022). Another cross-sectional survey conducted in 2021 showed that among young adults using disposable e-cigarettes, fruit flavors were the most prevalent (47.0%), followed by sweet/dessert/candy (38.9%), and mint/menthol (34.9%) (McCauley et al., 2022). Furthermore, a study revealed a notable prevalence of disposable e-cigarette use among young adults, particularly among those who had never used tobacco products and former smokers, and it was associated with the use of cooling flavored e-cigarettes (Leventhal et al., 2022). Research indicates that sweet and cooling flavors play a role in tobacco use initiation among young individuals (Kreslake et al., 2008; Landry et al., 2019). However, it remains uncertain how sweet and cooling flavors in e-cigarettes relate to use of novel products such as NTN e-cigarettes. Given the popularity and novelty of NTN products, this study examined how the use of sweet (fruit/candy/dessert) and mint/menthol-flavored e-cigarettes relates to the use of and future susceptibility to NTN e-cigarettes among a national sample of US young adults.