Self‐derivation of new factual knowledge is crucial for building a knowledge base. In three experiments, we investigated self‐derivation about prescription medications. In Experiment 1, adults self‐derived new knowledge across textual materials on 40% of trials. Participants in Experiment 2 performed similarly (42%), even when half the information was presented in videos. It was crucial that participants received both learning episodes to successfully self‐derive: control condition participants received half the necessary information and performed significantly lower. When a delay was imposed between related facts in Experiment 3, participants self‐derived on only 33% of trials and performance did not differ from the control condition. The present research expanded our understanding of adults' learning and self‐derivation across media about medications. It revealed room for improvement in adults' learning and self‐derivation about health information. This work suggests the need to identify factors that alter performance, including better understanding of the properties of information sources.