Introduction: This research examines cigarette smokers' and e-cigarette users' product-related health-risk beliefs across tobacco products and considers the effects of addiction warnings on consumers' responses to persuasion attempts.Aims and Methods: Study 1 used a cross-sectional survey with a sample of 195 adult cigarette smokers, e-cigarette users, and dual users to examine health-risk beliefs associated with combustible cigarettes and e-cigarettes (cancer, lung disease, stroke, heart disease, harm to an unborn baby, and addiction). Using a sample of 265 adult cigarette smokers, e-cigarette users, and dual users, Study 2 used a between-subjects experiment to examine the effects of an addiction warning presented in an advertisement on health-risk beliefs and willingness to try the promoted product.Results: Study 1 results reveal that health-risk beliefs for cigarettes are extremely high, whereas health-risk beliefs for e-cigarettes are lower and vary across specific health-risk beliefs; specifically, beliefs related to addiction and harm to an unborn baby are greater than other risk beliefs. Extending these findings, Study 2 results demonstrate that health-risk beliefs associated with cigarette smoking are not affected by an addiction warning in a cigarette advertisement. However, an addiction warning in an e-cigarette advertisement does modify e-cigarette-related risk beliefs, which, in turn, reduces consumers' willingness to try the promoted e-cigarette.Conclusions: Findings indicate that the addition of an addiction warning may be effective in changing consumers' risk beliefs associated with e-cigarettes and consumers' responses to e-cigarette persuasion attempts.Implications: By examining cigarette smokers' and e-cigarette users' product-related health-risk beliefs and considering the effects of an addiction warning on consumers' responses to persuasion attempts, this research contributes to the understanding of how warnings in tobacco promotion affect cigarette smokers', e-cigarette users', and dual users' health-risk beliefs and willingness to try promoted products. Specifically, findings show that health-risk beliefs associated with e-cigarettes can be modified using an addiction warning in an e-cigarette advertisement, whereas health-risk beliefs associated with combustible cigarettes are not influenced by an addiction warning. [ABSTRACT FROM AUTHOR]