Purple toenail, may be trauma, local blood circulation is not good, but also to understand whether it is related to pathological factors. 1. Trauma: purple toenail color, consider and trauma related, such as smashing, resulting in subnail bleeding, may lead to purple toenail color. 2. Poor blood circulation: If you are in a cold and oxygen-deprived environment for a long period of time, it will have an impact on the local blood circulation, leading to ischemia and lack of oxygen in the toe area, resulting in purple toenails. 3. Pathological factors: such as respiratory diseases, heart disease, will have an impact on the local blood supply, resulting in purple toenails. In addition to this, we also need to know whether it is related to external coloring, causing purple toenails. It is recommended to identify the cause before proceeding with the treatment.