Usually, a low-grade fever of more than 1 week is more dangerous, but patients need to be analyzed according to the presence of primary illnesses and comorbidities. For hypothermia caused by the common cold, patients with fever will usually improve or be cured to varying degrees within 1 week. Viral cold is a self-limiting disease, and the hypothermia caused by it can be cured within 1 week with proper rest and treatment. In addition, there are many other clinical causes of hypothermia, such as mycoplasma infection, tuberculosis, tumor, rheumatism, AIDS, etc. Therefore, it is recommended to go to the hospital to find out the cause of hypothermia after it lasts for more than 1 week. Also, if the patient has a low resistance and a serious medical disease combined with a low fever period, it is recommended to go to the hospital early for systematic examination and regular treatment. In addition, for patients with long-term recurrent low-grade fever, it is recommended not to abuse antipyretic drugs on their own, so as not to influence the doctor’s judgment of the fever type, and to pay attention to more rest, more water and nutritious food.