BackgroundExposure to social media content promoting e-cigarette use (“vaping”) is associated with subsequent tobacco use among young adults. Adding features to pro-vaping Instagram influencer posts, such as a nicotine warning label and vaping cessation resources, could help counteract posts’ negative influence. MethodsYoung adults (N = 2,179; Mage = 22.6 [SD = 0.4]; 53.0 % cisgender women, 45.1 % Hispanic) completed an online experiment in 2021–2022 through an ongoing prospective cohort study. Participants viewed three simulated pro-vaping Instagram influencer posts in a four-group, between-subjects design. Post features differed by experimental condition: “label-only” (nicotine warning label on post), “link-only” (link to vaping cessation resources under post), “L&L” (label and link), or “control” (neither). Participants rated each influencer’s traits (honest, trustworthy, informed, smart, attractive, popular; 0–100 %). After viewing all three posts, participants reported use intentions, susceptibility, positive and negative expectancies, and harm perceptions around the fictitious advertised vaping product. Past-month vapers additionally reported their desire and self-efficacy for quitting. ResultsL&L (versus control and link-only) participants viewed influencers as more honest, trustworthy, and informed. L&L (versus control) participants had lower odds of susceptibility to using the advertised product, lower positive expectancies, and greater negative expectancies. The label and link did not significantly affect participants’ intentions to use the product, perceived harm of the product, or desire or self-efficacy for quitting vaping. ConclusionsProviding a nicotine warning label and link to vaping cessation resources on influencers’ Instagram posts may have the unintended effect of increasing positive perceptions of the influencer. However, they may reduce susceptibility to product use.