Wireless Sensor Network (WSN) is a very important part of Internet of Things (IoT), especially in e-healthcare applications. Among them, wireless medical sensor networks (WMSNs) have been used in the personalized healthcare systems (PHSs). In recent years, professionals use their mobile devices to access the data collected from sensors which are placed in or on patients’ bodies. Due to the danger of wireless transmission circumstance, the security of the data which are collected by the sensors and also transmitted to the doctors faces challenges. In the past decade, many authentication schemes for WMSNs are proposed. However, security disadvantages have been found in such schemes. To overcome the historical security problems, we propose a robust and lightweight authentication scheme for WMSNs, which meets the common security requirements, and keeps away user tracking from attackers. The popular tool Proverif is employed to express that our scheme resists the simulated attacks. Also, the informal security analysis is demonstrated. With the comparison to several very recent schemes and simulation by NS-3, the proposed scheme is suitable for PHSs. •A lightweight two-factor authentication scheme using WMSNs away from being tracked is presented.•We use the famous tool Proverif to prove that our scheme is secure against the common attacks.•The informal analysis and performance comparison with recent schemes show that ours is the best.•The simulation with NS-3 shows that our scheme is applicable for practice.