Medication errors can lead to harm in hospitalized patients including increased length of stay, lower quality of life, increased morbidity, and even death. This review of 65 studies and 110,875 patients examined interventions (primarily medication reconciliation) and their effect on reducing adverse drug events. Findings revealed mostly low to moderate certainty about the effectiveness of medication reconciliation and low certainty on other interventions, emphasizing the importance of research that has greater power and is methodologically sound.