If the recurring fever is more than 38 ℃ for five or six days, it may be due to influenza without the use of antiviral drugs or insufficient dosage of drugs, mixed infections, combined with other diseases and other conditions. 1. Insufficient drug dosage: Fever caused by common cold is generally low and self-limiting, and can be cured in 5-7 days. Influenza requires the use of antiviral drugs at an early stage. If antiviral drugs are not used or the dosage of drugs is not enough, the disease may not be controlled and recurrent fever may occur. 2. Mixed infection: If the patient has upper respiratory tract infection with secondary bacterial infection, it may lead to recurrent fever above 38℃ for five or six days. 3. Other diseases: Fever of 38 ℃ is not necessarily caused by colds, there may be other diseases, such as immune disease rheumatic fever or oncological diseases such as lymphoma. It is recommended that patients with recurrent fever should consult a doctor in time to clarify the cause of the disease and follow the doctor’s instructions strictly for reasonable treatment.