Optimising messages and images for e-cigarette warnings.

Background: The US Food and Drug Administration (FDA) requires electronic cigarettes (e-cigarettes) to have a single addiction warning, but many other health harms are associated with vaping and warnings grow stale over time. We aimed to develop new warning messages and images to discourage e-cigarette use.

Methods: Participants were 1629 US adults who vaped or smoked. We randomised each participant to evaluate 7 of 28 messages on newly developed (metals exposure, DNA mutation, cardiovascular problems, chemical exposure, lung damage, impaired immunity, addiction), and the current FDA-required warning (total of 8 messages). Then, participants evaluated images of hazards (eg, metal), internal harms (eg, organ damage) or people experiencing harms.

Results: Regarding intended effects, new warning themes all discouraged vaping more than the current FDA-required warning (all p<0.001), led to greater negative affect (all p<0.001) and led to more anticipated social interactions (all p<0.001). The most discouraging warnings were about toxic metals exposure. Regarding unintended effects, the new themes led to more stigma against people who vape (6 of 7 themes, p<0.001) and led to a greater likelihood of thinking vaping is more harmful than smoking (all 7 themes, p<0.001), although unintended effects were smaller than intended effects. Images of harms (internal or people experiencing) discouraged vaping more than images of hazards (all p<0.001).

Discussion: Vaping warning policies should communicate a broader range of hazards and harms, beyond addiction, to potentially increase awareness of health harms. Images of internal harm or people experiencing harms may be particularly effective at discouraging vaping.