The causes of recurring fever include incomplete treatment of colds and lung infections, while malignant tumors and connective tissue diseases cannot be ruled out. The most common reason for recurrent fever is incomplete treatment. Upper respiratory tract infections are usually caused by viral infections, but if combined with bacterial infections, the fever may subside temporarily after symptomatic treatment, but the treatment is incomplete due to failure to treat the whole process regularly, and subsequent recurrent fever may occur. At the same time does not exclude the possibility of lung infection, the cold has been cured, but there may be a lung infection, leading to the emergence of repeated fever symptoms, need to consult a doctor in a timely manner for X-ray and other tests to make clear, and at the same time under the guidance of the doctor for timely treatment. In addition, malignant tumors and connective tissue diseases may also cause fever, and timely examination is recommended to rule out the diagnosis.