Improving medication safety at home for children with medical complexity (CMC) is a priority among pediatric care providers. In this study, researchers engaged 16 caregivers and clinicians in a co-design process to develop a mobile health application to improve medication safety for CMC in the home. This process identified several medication safety challenges (e.g., correct dosage/route, timely refills, communicating about medications in and outside of the home), and the co-designers proposed prototype features that could address these concerns.