Wireless body area network (WBAN) is a remarkable, reliable and the most beneficial trend in the e-health monitoring system. WBANs are operated using low power wireless technology to link minute sensors with invasive or non-invasive technology for examining the patients. WBANs when used in a dense environment or operated along with other wireless sensor networks, there occurs communication interference which may reduce the system performance due to unstable signal integrity. So interference mitigation should be considered in the design. The interference is basically of two types: internetwork and intra-network interference. This paper focuses on a comparative study of mitigation techniques of inter-network interference and also discusses the open issues in WBAN. © Springer Science+Business Media, LLC 2017.