After a child has a fever, the routine blood test is mainly to observe whether the white blood cells and neutrophils are increased, and also to see whether the lymphocytes are normal. If you simply check the routine blood test, you can usually eat and do not need to fast. If you also need to check the liver and kidney function, you need to fasting. Children can drink a lot of warm water during the fever to meet the body’s need for water, but also to speed up the body’s metabolism, which is helpful in reducing fever. Children can also eat fresh vegetables and fruits during the fever to meet the body’s requirement for vitamin C. In life, we often eat vegetables and fruits such as apples, pears, pineapples, kiwis, green vegetables, spinach, cauliflower, etc. Children must pay attention to rest during the fever, do not go outdoors to engage in strenuous activities and sports, so as to avoid physical fatigue, which is not conducive to fever reduction.