Healthcare is one of the most promising application of IoT. Because of the critical nature of health-related data, it is important to transfer it securely on the network and allow only legitimate IoT devices to participate in the network. This paper proposed a mutually authenticated group key management protocol (MAGKMP) for healthcare applications of IoT. Each IoT device is properly authenticated before allowing it to join the network. It also provides the facility to IoT devices to authenticate the trusted servers and smart e-health gateways before sharing the session and group keys with them. For secure multicast communication, group keys are distributed securely after mutual authentication between different participating devices in the network. The analysis of proposed MAGKMP shows that it is secure against different types of attacks and provides mutual authentication and forward and backward secrecy in the group communication. It also offers load balancing among gateways by exploiting the context profile of gateways.