Impact of Instagram and TikTok influencer marketing on perceptions of e-cigarettes and perceptions of influencers in young adults: a randomised survey-based experiment

Background Pairing e-cigarettes with healthy lifestyle contexts in influencers' promotional social media posts may increase e-cigarette use risk among young adults. This study examined the effects of e-cigarette and healthy lifestyle content on young adults' perceptions of influencer credibility, harm perceptions of, and susceptibility to use, e-cigarettes.Methods In this survey-based online, repeated-measures experiment (2023), California young adults (N=1494, Mage=23 (SD=1.8); 63% female, 51% Hispanic) were randomly shown 10 (total) Instagram and TikTok videos, featuring influencers promoting e-cigarettes alongside healthy lifestyle activities (experimental group), or a healthy lifestyle activity alone (control). After watching each video, participants rated perceived influencer credibility (eg, honesty). After watching all videos, harm perceptions of e-cigarettes were assessed among all participants and susceptibility to e-cigarette use was assessed among e-cigarette never-users. Harm perceptions and susceptibility outcomes were compared between groups (experimental vs control) and between participants who perceived influencers as credible versus non-credible, using binomial generalised linear mixed effects models.Results Participants in the experimental group were more likely to report lower harm perceptions (adjusted OR (AOR) 1.12; 95% CI 1.03; 1.21) and higher susceptibility to e-cigarette use (AOR 1.22, 95% CI 1.11; 1.34), than participants in the control condition. Similar results were found when influencers were perceived as credible, but not when they were perceived as non-credible.Conclusions Social media influencers' posts promoting e-cigarette use along with healthy activities may contribute to young adult e-cigarette use. Decreasing perceived credibility of influencers could decrease the negative effects of their promotional posts.Trial registration number NCT06433466.