Fever can be seen in a variety of diseases, so the precursor symptoms are different, can be simply divided into systemic symptoms, respiratory symptoms, digestive symptoms, urinary symptoms. 1. Systemic symptoms: In the early stage of fever, patients may have clinical symptoms such as generalized chills, chills, fatigue, and limb pain. 2. Respiratory symptoms: patients may have different degrees of nasal congestion, runny nose and other clinical manifestations before the fever. 3. Digestive system symptoms: patients may have digestive system symptoms such as loss of appetite, nausea and vomiting. 4. Urinary system symptoms: If the fever is caused by urinary system infection, symptoms such as frequent urination and painful urination may occur. Once the above symptoms appear, you must observe more, and consult the doctor promptly if you feel unwell.