A fever of one week is not normal. An abnormal body temperature of one week indicates the presence of a disease, most often a bacterial or viral infection, which can affect health if the fever continues to rise, and failure to identify the cause of the fever and treat it promptly can delay the condition and cause serious consequences. Fever for a week can be caused by diseases of the immune system, such as rheumatic diseases or systemic lupus erythematosus, and tuberculosis or hematologic diseases cannot be excluded. The diagnosis of a specific disease is based on the symptoms accompanying the fever, the patient’s age, medical history and signs. If the body temperature is abnormal, the cause must be identified and treated without delay, and a body temperature greater than 37.3°C is abnormal. Fever can be seen in diseases of several systems, such as respiratory system, digestive system, urinary system, nervous system, hematological system, endocrine system, nervous system, etc.