Warning and informative messages on e-cigarette package leaflets: A Belgian policy case study for public health policymakers.

The EU Tobacco Products Directive specifies the types of information required on e-cigarette package leaflets, but leaves further details and design to the Member States. In practice, however, both aspects are largely determined by the industry. This policy case study presents a comprehensive leaflet proposal developed by the Belgian Superior Health Council in collaboration with national tobacco control stakeholders. This multidisciplinary engagement enhances both the content quality and its acceptance among health professionals. The proposal defines formatting requirements for maximum legibility and comprehension across the general population, and structures evidence-based warning and informative messages into five thematic chapters. It aims to prevent vaping initiation among non-smokers and specific vulnerable groups by highlighting both short- and long-term health risks, while providing adult smokers with balanced information on the potential role of e-cigarettes in smoking cessation, preferably under professional supervision. The content should be updated periodically to reflect new scientific evidence, and complemented with evaluation metrics to assess real-world impact (leaflet reach, reader comprehension, behavioral influence). Given that leaflets are poorly to moderately noticed and rarely read, integration with pictorial warnings is recommended, following the relatively successful Canadian model for cigarette package inserts.