Public health campaigns that raise awareness about mental health problems are designed to decrease stigma, increase help-seeking and improve mental health literacy. However, there is some theoretical concern that, alongside benefits, such campaigns might negatively impact how some individuals interpret, label and respond to mental health problems. In this Review, we summarize the extant evidence for the positive and negative psychological impacts of mental health awareness efforts. We integrate theoretical literature with studies using experimental designs in which mental health awareness content is manipulated in a controlled environment that might provide preliminary insights into potential causal relationships. We find that awareness materials can change cognitions and beliefs relating to one’s own mental health and to mental health more generally (such as self-diagnosis and beliefs about recovery). These effects can vary depending on individual characteristics (such as existing symptoms, stability of self-concept and suggestibility), the message being presented, identification with the messenger, and whether there is personalized information about one’s own symptoms. We discuss the implications of this work for adolescent populations and directions for future research.