There are red blood cells, white blood cells and platelets in human blood, each with its own function. Leukocytes are a health-protecting warrior with a tough team and a strong fighting force. Their life span in the human body is shorter than that of red blood cells, about 7-9 days, and their main function is to destroy the invading germs. Once the germs invade, it takes only a few minutes for the leukocytes to move to the site where the germs invade, and for about a few hours the leukocytes can adsorb to the site with inflammation, surround, engulf and finally destroy the pathogenic germs. Under normal conditions, the number of leukocytes is highly variable and its normal value is: 10-20×109/liter for newborns, 5-12×109/liter in infancy, and 4-10×109/liter when approaching adult level after 5-6 years of age. If the value is lower than 4×109/liter when blood is drawn from the finger or earlobe for laboratory tests, then leukopenia is considered. There are many causes of leukopenia, and antipyretics are one of them. Most of them are caused by parents who take a lot of antipyretics for their feverish children and sometimes use adult antipyretic tablets. The child’s white blood cells can be reduced to 0.8×109/liter or lower, and the child appears tired and pale. Individual parents have a misconception that if the temperature is lowered, the disease is cured. In fact, sometimes, illnesses such as colds and viral infections can themselves cause temporary leukopenia, which can be exacerbated by the use of too much antipyretic medication. How can antipyretics cause leukopenia? As antipyretics enter the body, they “denature” the white blood cells, and the body considers the denatured white blood cells as a foreign body and produces an anti-white blood cell substance to destroy the denatured white blood cells, which is called anti-white blood cell antibodies. The anti-white blood cell antibodies react with the white blood cells (called immune reaction) and destroy the white blood cells, causing a decrease in the number of white blood cells in the body and weakening the overall white blood cell power. In children with leukopenia, doctors will order repeated blood tests to observe the degree of leukopenia and, if necessary, use leukocyte-raising drugs. It is normal for modern families to have their own antipyretics, and it is very common for children to take their own antipyretics for fever. However, the use of aminopyrine and pau d’arco should be minimized or not used. What should I do if my child has a fever that does not subside? Suggestions: ①Use medication under the guidance of a doctor who will try to choose medication that is less toxic to the child and can achieve the treatment purpose according to the condition. ②It is best to take antipyretic drugs for children with fever of 38.5℃ or more and who are uncomfortable or have a history of febrile seizures. ③ Drink more boiled water, loosen clothes, cover less, if you can cool down slowly, it is better not to use antipyretic drugs. ④Physical cooling, 75% alcohol or household liquor can be used to rub the body, except for the abdomen can not be rubbed, other parts can be rubbed with white clean fine cloth with alcohol, after rubbing should be covered with towel quilt or thin quilt, so as to avoid excessive exposure, heat dissipation too fast. ⑤ Use a hot water bag filled with tap water pillow, or put it on the part of the groin where the large blood vessels go to cool down. ⑥Neonates should not be given intramuscular antipyretic injections or take antipyretic drugs.