The Internet of Things (IoT) is a technology that connects physical objects to each other using a variety of digital systems. This technology has many applications, particularly in the field of medical monitoring. For this, a specific network called Wireless Body Area Network (WBAN) can be integrated into the IoT network. These networks are made up of sensors that measure patients’ health parameters. The growing use of wireless body area networks (WBANs) in the medical field offers many advantages in terms of monitoring and healthcare. However, like any distributed system, WBANs also face design challenges such as fault-tolerance, quality of service, and data loss, while ensuring patient comfort. In this article, we present a new tree-based routing protocol, called Fault-tolerance Routing-Based Tree (FTRBT). The aim of this protocol is to guarantee availability, fault-tolerance, and quality of service in terms of delay and storage. To evaluate the effectiveness of this protocol, we compared its performance to that of a random routing protocol, without resorting to the use of a pre-established virtual architecture. This evaluation was carried out using the Castalia simulator based on OM-Net++. The results of our simulations and comparison demonstrate the effectiveness of the FTRBT protocol in detecting and tolerating faults within WBANs.