Identifying and preventing drug-drug interactions (DDI) is critical to patient safety, but the usual method of detecting DDI and other errors - manual chart review - is resource intensive. This study describes the use of an e-trigger to pre-select charts for review that are more likely to include one of three DDIs, thus reducing the overall number of charts needing review. Two of the DDI e-triggers had high positive predictive values (0.76 and 0.57), demonstrating that e-triggers can be a useful method to pre-selecting charts for manual review.