Is it possible to be so sick that you start to lose your hair? Can a high fever cause hair shedding? Sometimes when you are sick and have a high fever, your body undergoes high levels of stress. When this happens, various factors impact your body's functions, including the growth of your hair.Is it possible to be so sick that you start to lose your hair? Can a high fever cause hair shedding? Sometimes when you are sick and have a high fever, your body undergoes high levels of stress. When this happens, various factors impact your body's functions, including the growth of your hair.