Abstract
Antibiotic overuse is a significant public health challenge, and antibiotics are often prescribed as a precaution. While precautionary prescribing often aims to meet perceived patient expectations, it can unintentionally reinforce the belief that antibiotics are necessary and effective. This study examines how the communication of precautionary antibiotic prescribing shapes patients' beliefs in what actually made them better and how these causal beliefs, in turn, affect their expectations for antibiotics in future illness situations. In the two preregistered online experiments with UK adults (N = 252 and N = 2448), participants imagined having an ear infection, receiving a precautionary prescription, taking antibiotics, and recovering shortly thereafter. We manipulated whether participants received statistical information about the likelihood of a self-limiting recovery (base-rate information) before the prescription. Participants then evaluated what caused their recovery and whether they expected to receive antibiotics for a future, unrelated illness. Across both studies, participants generally attributed their recovery to the antibiotics, even when told that the infection was likely to resolve on its own. This attribution was associated with stronger expectations of receiving antibiotics for future illnesses. However, participants who received base-rate information more accurately attributed their recovery, suggesting that statistical context can partially correct causal beliefs. Precautionary prescribing can unintentionally shape patients' beliefs about antibiotic efficacy, which, in turn, reinforces future demand. Providing patients with brief information on self-limiting infections may help reduce inappropriate antibiotic expectations and support prudent and more sustainable prescribing practices.