The increasing demand for efficient healthcare has spurred the adoption of IoT technologies, promising reduced costs and improved outcomes. This study addresses the integration of IoT in healthcare, focusing on patient-centered applications across prevention, diagnosis, and treatment. We explore three research questions concerning the main IoT applications, their drivers and challenges, and their impact on healthcare delivery. This systematic literature review synthesizes evidence from the literature to identify trends and mappings in IoT applications. The review includes a comprehensive framework for IoT in healthcare, enhancing patient engagement and care delivery. The study is structured first to define IoT paradigms and technologies, followed by proposing a healthcare framework, describing our methodology, and discussing the implications of our findings on future healthcare innovations.