Purpose: We assessed the potential for harmful messages in online advertisements targeted to youth, using the example of the Canadian “Light It Up” marketing campaign from a large sports corporation. Methods: We undertook a cluster randomized controlled trial of 20 secondary school classes in Montreal, Canada. Classes were randomly allocated to view a “Light It Up” advertisement (n ¼ 205) or a neutral comparison advertisement (n ¼ 192). The main outcome measures were self-reports of illicit drug messages in the advertisements. Results: Of the students, 22.9% reported that the “Light It Up” advertisement contained illicit drug messages compared with 1.0% for the comparison advertisement (relative risk, 22.0; 95% confidence interval, 6.5e74.9). Conclusions: Although meant to promote sports, youth in this study believed that the “Light It Up” advertisement was related to illicit drugs. The campaign illustrates how advertisements may inadvertently market unwanted behaviors to children.
