Fever blood tests do not require fasting. Fever blood tests are mainly for routine blood tests and C-reactive protein, which can be checked at any time at this time, without fasting or any preparation, and you can eat and drink normally. Most fevers are caused by viral or bacterial infections, so if you have a fever for three consecutive days and your body temperature is above 37.3℃, it is best to go to the hospital for blood tests. If there is cough, chest pain, chest tightness, shortness of breath, it is best to have your chest CT and ECG checked as well to rule out respiratory diseases such as bronchitis, pneumonia, pleural effusion, or cardiovascular diseases such as coronary heart disease, angina pectoris, viral Myocarditis, etc. Fever is a symptom that can be caused by several systemic diseases, the most common being acute upper respiratory tract infections, such as nasal congestion, runny nose, sneezing and sore throat.