AbstractDuring the COVID-19 pandemic, public health guidance (e.g., regarding the use of non-medical masks) changed over time. Although many revisions were a result of gains in scientific understanding, we nonetheless hypothesized that making changes in guidance salient would negatively affect evaluations of experts and health-protective intentions. In Study 1 (N= 300), we demonstrate that describing COVID-19 guidance in terms of inconsistency (versus consistency) leads people to perceive scientists and public health authorities less favorably (e.g., as less expert). For participants in Canada (n= 190), though not the U.S. (n= 110), making guidance change salient also reduced intentions to download a contact tracing app. In Study 2 (N= 1399), we show that a brief forewarning intervention mitigates detrimental effects of changes in guidance. In the absence of forewarning, emphasizing inconsistency harmed judgments of public health authorities and reduced health-protective intentions, but forewarning eliminated this effect.