Abstract
HIGHLIGHTS: Public health relevance—How does this work relate to a public health issue? The rising prevalence of vaping among young never-smokers represents a serious public health concern. While flavours strongly increase the appeal of e-cigarettes to youths, flavouring substances contribute to the overall toxicity of vaping. Public health significance—Why is this work of significance to public health? This work provides a highly multidisciplinary synthesis of the e-cigarette flavour issue, covering toxicity, attractiveness, and international regulatory responses. It reviews international flavour ban experiences to inform policymakers on best practices, expected outcomes, and potential pitfalls. Public health implications—What are the key implications or messages for practitioners, policy makers and/or researchers in public health? Banning non-tobacco e-cigarette flavours is a key measure to reduce youth appeal, e-cigarette use and initiation. Post-ban, effective enforcement, sound legislation, and comprehensive tobacco control strategies are crucial to prevent illicit sales, industry circumvention, and substitution to smoking. ABSTRACT: Background: E-cigarette use has risen sharply among young never-smokers, largely driven by the availability of several thousand appealing flavours. This narrative review synthesises evidence on the health effects of vaping, flavour toxicology and attractiveness, designs and outcomes of flavour bans, and complementary measures. Methods: Peer-reviewed publications and institutional reports (up to January 2026) were retrieved from PubMed, Web of Science, Google Scholar, and reference lists of included articles. Evidence from about 200 references was synthesised by a multidisciplinary working group. Results: Although flavouring substances are generally considered safe for ingestion, their inhalation toxicity remains uncertain. In vitro and in vivo studies have reported oxidative stress, inflammation, cytotoxicity, impaired ciliary function, transcriptomic changes, genotoxicity, and DNA damage. These findings—along with the strong youth appeal of fruit/sweet flavours, the inconclusive effects of flavours on smoking cessation, and persisting uncertainties—support banning non-tobacco e-cigarette flavours under the precautionary principle. Flavour bans can reduce e-cigarette use and initiation, especially among young adults, although partial substitution towards combustible cigarettes has been reported in some U.S. states. Policy success requires effective enforcement, prevention of industry circumvention, curbing cross-border sales, and closing regulatory loopholes—ideally at the international level (e.g., EU-wide). Conclusions: E-cigarette flavours may increase vaping toxicity and strongly appeal to youth, justifying flavour bans to prioritise youth protection. To maximise effectiveness, accompanying measures and sustained investment in tobacco prevention, youth education, and accessible evidence-based smoking cessation support are essential.