Blockchain-based solutions for Internet of Things (IoT) networks constitutes a current trend in cybersecurity and brings significant benefits into current centralized IoT-based health monitoring systems by addressing security challenges. Complex and power intense blockchain solutions do not perform satisfactory in the resource-constrained IoT, and especially Internet of Medical Things (IoMT), devices of these systems due to the latter's limited processing power, storage capacity, and battery life. Therefore, in this paper, we propose a scalable Practical Byzantine Fault Tolerance (PBFT) consensus algorithm for IoMT blockchains to: i) enhance scalability in IoMT blockchains, ii) reduce communication overhead, iii) enhance security while reducing the computational cost for suitability to the resource constraint nature of IoMT devices, iv) facilitate decentralized accountability, and v) eliminate single point of failure.