Abstract
This paper examines how direct-to-consumer advertising (DTCA) for prescription drugs influences utilization by exploiting a large and plausibly exogenous shock to DTCA driven by the introduction of Medicare Part D. Part D led to larger increases in advertising in geographic areas with higher concentrations of Medicare beneficiaries. We examine the impact of this differential increase in advertising on non-elderly individuals to isolate advertising effects from the direct effects of Part D. We find that exposure to advertising led to large increases in treatment initiation and improved medication adherence. Advertising also had sizeable positive spillover effects on non-advertised generic drugs. Our results imply significant spillovers from Medicare Part D on the under-65 population and an important role for non-price factors in influencing prescription drug utilization.