Borrowing insights from the consumer knowledge and the direct-to-consumer prescription drug advertising (DTCA) risk communication literature, the current study examined how consumers' regulatory knowledge regarding DTCA affects attention to and awareness of risk information in DTCA. The moderating role of risk information prominence and the mediating mechanism of attention were also explored. Taking an experimental design approach using a sample of US consumers (N = 264), risk information prominence was manipulated using various message attributes (e.g., font, color, size, box line, thickness, proximity). The study found that consumers' higher regulatory knowledge led to greater attention to risk information when the health risks of the advertised drug were presented less prominently, compared with when the risks were salient. The regulatory knowledge enhanced consumer recall and recognition of the drug's health risks through attention, but the indirect effects were dependent on the disclosure prominence level, such that the effects were more apparent when the prominence was low. This study manifests the value of consumers' regulatory literacy of DTCA to make informed prescription medication decisions and advises pharmaceutical marketers to present noticeable health risk information to encourage consumers to consider important health risks of promoted drugs in their decision making.