AimsA warning on e-cigarette packaging is one way the U.S. government can inform the public of known harms of e-cigarette use. Currently, the only required warning on these products is: “WARNING:This product contains nicotine. Nicotine is an addictive chemical.” This exploratory study aims to inform potential future investigations and FDA decisions regarding alternative warnings that may generate fear in addition to being intentionally informational.MethodData were obtained from responses by 16 online focus groups with adult (N = 47, age range = 18–64) and youth (N = 32, age range 14–16) participants with various smoking and vaping experiences. We showed each focus group a set of hypothetical e-cigarette warning labels to determine how they respond to currently existing public statements that communicate information on the toxicity of ingredients in e-cigarettes, potential health risks, addiction to nicotine, and the uncertainty of the science regarding health effects of using these products. The focus group interviews were audio recorded and transcribed. Transcripts were subjected to a multiphase coding process to identify common response themes. Codes derived from the Extended Parallel Processing Model were then applied to understand impact of potentially fear-inducing language by warning category and age group.ResultsFor adults, all warnings—except those about addiction—gave rise to spontaneous danger control (intended) responses, such as quit intentions. Warnings highlighting cognitive and uncertain effects may be particularly promising for adult consumers of tobacco products because both gengerated danger control and response efficacy without evidence of fear control. However, responses also suggest that warnings risk discouraging some adults who use combustible cigarettes from transitioning to e-cigarettes for harm reduction. For youth, while evidence of response efficacy and danger control emerged among youth exposed to messages in all warning categories but one–addiction—unproductive reactions indicative of fear control were also prevalent among youth respondent across most warning types. On average, youth were more skeptical than adults about the harms of using e-cigarettes.Policy implicationsImplications of study findings for the development of future effective e-cigarette warning messages are explored.