This guidance is intended to help sponsors of investigational new drug applications (INDs) and new drug applications (NDAs) evaluate the need for drug-drug interaction (DDI) studies of their investigational drugs with combined oral contraceptives (COCs), design such studies, and determine how to communicate DDI study results and mitigation strategies to address potential risks associated with increased or decreased exposure of COCs in labeling. This guidance focuses on evaluating the DDI potential of an investigational drug (i.e., perpetrator) on a COC (i.e., victim).