Low fever has little to do with weather changes. If the fever is recurrent but the patient is in good spirits, it may be due to infectious diseases (e.g. bacterial infection) and non-infectious diseases (e.g. hyperthyroidism, etc.), which can be treated with medication or surgery according to the condition. 1. Infectious diseases: such as upper respiratory tract infection, tuberculosis, etc., can cause recurrent low-grade fever, and may be accompanied by cough and sputum, etc. Chest X-ray/CT, tuberculin test, etc. can assist in the diagnosis, and can be treated with antibiotics (e.g., cefuroxime, etc.) to fight infection, anti-tuberculosis drugs (e.g., rifampicin, isoniazid, etc.). 2. Non-infectious diseases: such as hyperthyroidism, hyperthyroidism due to increased levels of thyroid hormones, the body’s metabolism level increases, so there will be a low-grade fever, but also may be accompanied by panic, weight loss and other symptoms, thyroid function and other tests can assist in the definitive diagnosis, can be given medication (eg, mercaptoimidazole, etc.), surgery and other treatments. If the above situation occurs, it is recommended to consult a doctor in time to make a clear diagnosis to avoid delaying the condition.