Purpose -The over-the-counter (OTC) drug market is highly competitive, and consumer advertising is a prominent influence in OTC drug purchase and consumption. Given current marketplace conditions, it is important to summarize OTC drug advertising research. This paper aims to review the state of the public research literature on OTC drug advertising and provide a research agenda derived from the findings. Design/methodology/approach -A literature review was conducted to identify the key themes in OTC drug advertising research and secondary data were collected about the regulation, nature, functions, and scope of OTC drug advertising. Findings -Most pharmaceutical advertising studies have focused on prescription drugs, including the majority of direct-to-consumer advertising investigations. OTC drug advertising has received considerably less empirical attention. Since the mid-1970s, only 24 OTC drug advertising studies have appeared sporadically in the literature. The cumulative findings are interesting and suggestive but dated, fragmented, and incomplete. Though research interest has waned, OTC drug markets and advertising spending have not. Advertising remains a prominent OTC drug purchase and consumption driver, likely spurred on by self-medication and Rx-to-OTC drug switching. The state of the public research, the social and policy implications of self-medication, and the growing OTC drug market signal that it is time to revisit OTC drug advertising content, processes, and effects. Originality/value -The paper puts the subject of OTC drug advertising back on the radar of communication, advertising, and pharmaceutical marketing researchers and offers an agenda of research questions derived from the reviewed literature to guide and stimulate future studies.