Under a new Food and Drug Administration's proposal, consumers could receive an information leaflet, called a patient package insert or PPI, with most prescription drugs. This study examines the effects of providing side effect information on people's perceptions of risk and intentions to take a hypothetical drug. In a between‐subjects experiment, using nine groups of subjects receiving different side effect information, the study found that subjects were sensitive to large differences in the number of side effects, their degrees of seriousness, as well as their frequency of occurrence; however, subjects could not discriminate small differences. Several implications of the study are important to researchers and designers of consumer information programs that are concerned with risk assessment.