In this paper, we introduce the novel concept of cost-effective mobile health care which leverages the multiple wireless interfaces onboard most mobile phones today. First, we study the problem of uploading medical data using the “least cost” radio interface. Toward this objective, we propose the wireless interface selection algorithm (WISA) which decides the wireless interface yielding the least cost, depending on the data size, modality, and quality of service (QoS). Second, we study using modeling and simulations, the problem of cost-effective medical advisory message dissemination (on the downlink) which gives rise to an interesting cost-delay trade-off when leveraging free short-range phone-to-phone (P2P) communication. Finally, we build a proof-of-concept testbed, coined CellChek, which showcases the proposed WISA algorithm and demonstrates its operation using sample wireless-enabled medical devices, namely pulse oximeter and blood pressure monitor. The experimental results gathered using the prototype provide key insights into the system and the involved tradeoffs. The concepts explored in this paper along with the proposed schemes hold great promise for this emerging area of research that is of equal importance to developing and developed countries promising considerable cost savings.