A short-lived low-grade fever after a cold is usually not a cause for concern, but if the cold is followed by a prolonged period of low-grade fever, it may be considered abnormal. If a cold is followed by a low fever for only a short period of time, there is usually no need to worry too much. This is because colds are associated with viral infections and may be combined with or secondary to bacterial infections. When stimulated by pathogenic bacteria, the body’s immune system produces an immune response, causing a low fever, which is a relatively common symptom of the disease, and after the cold improves, the symptoms will gradually disappear and the body temperature will return to normal. However, if the fever is prolonged after a cold, and the patient has symptoms such as fatigue, body weakness and poor mental state, it is considered abnormal, and may be due to the seriousness of the disease or a combination of other diseases, such as rheumatoid immunity-related diseases. If the low fever does not go away after a cold, it is necessary to consult a doctor in time and analyze the cause of the disease through routine blood tests, C-reactive protein, tumor markers and other tests before regular treatment.