Patient portals facilitate active participation in self-care and decision-making, promoting high-quality care. During the COVID-19 pandemic, asynchronous messaging became a key tool for coordinating virtual care and reducing unnecessary hospital visits. This study examines the redesign of the messaging module in the mobile version of the patient portal at Hospital Italiano de Buenos Aires, with the aim of improving its usability and functionality. A participatory co-design approach was employed, based on user needs and technical feedback. Key improvements include the relocation of the module for easier access, optimized notifications, and greater clarity regarding message acceptance by healthcare professionals. These modifications are expected to enhance the transparency and usability of communication through the patient portal. Future research should assess the impact on patient satisfaction, response times, and the frequency of use of the messaging system.