Fever is usually a symptom caused by bacteria, viruses or their metabolites. The essence of fever is a self-protective reaction of the body, when bacteria or viruses invade the organism causing a febrile response, when the body increases the production of antibodies, the phagocytosis of white blood cells and the detoxification function of the liver, which helps to destroy the invading pathogens. Fever is not a disease per se, but a symptom. Fever itself can be caused by multiple types of diseases, such as colds, infections, tumors, autoimmune diseases and blood disorders. 1, the clinical causes of fever Clinical causes of fever are very complex, and antipyretic drugs are only a symptomatic treatment medicine, can not eliminate the cause, before a clear diagnosis, do not abuse antipyretic drugs at will, so as not to cover up the condition, affect the diagnosis and delay treatment. Moreover, the casual use of antipyretics not only does not eliminate the cause of the disease, but also affects the ability to resist the disease. Fever refers to the situation where the pyrogen acts directly on the thermoregulatory center, the dysfunction of the thermoregulatory center leads to the release of the mediators of the fever center or the excess heat production and reduced heat dissipation caused by various reasons, resulting in an increase in body temperature above the normal range. Fever is caused when bacteria, viruses, parasites, etc. invade the human body, or when extensive damage and destructive lesions occur in human tissues, or when the human central nervous system is dysfunctional, or when the human endocrine function is disrupted. When an infection is caused by various reasons, the body reacts to the infection by strengthening the function of phagocytes, stimulating the phagocytosis of the reticuloendothelial system through fever, facilitating the production of antibodies in the body, enhancing the activity of enzymes in the white blood cells and the detoxification of the liver to resist the attack of the disease on the body and promote recovery. Therefore, fever is a defensive response of the body to fight against pathogens. Generally speaking, fever is a protective response of the body. When the body is feverish, antibody production increases in the body, and the phagocytosis of leukocytes and detoxification of the liver are enhanced, which helps to destroy the invading pathogens. 2, clinically used therapeutic drugs Fever is a problem that everyone may encounter in life, and antipyretic drugs are also commonly available at home, and people will immediately think of taking antipyretic drugs as soon as they have a fever. Fever is often accompanied by painful sensations in the body because the pain-causing substances released by inflammatory substances acting on cells stimulate nerve end receptors and are transmitted to the cerebral cortex to produce nociception. The causes of fever and pain are very complex and require a clear clinical diagnosis before medication can be used; otherwise, the random abuse of antipyretic drugs is detrimental to the treatment of the disease, resulting in untimely treatment and delayed illness. If the fever is caused by acute and chronic inflammation, simply with antipyretic drugs, although the symptoms of fever can be relieved in the short term, but the cure is not the root cause, antipyretic drugs do not have the role of antibacterial anti-inflammatory, and may even lead to aggravation or worsening of the disease; at this time the first priority is antibacterial anti-inflammatory, with anti-inflammatory drugs for treatment, after a period of treatment, the inflammation subsides also naturally fever. Antipyretic drugs can restore the normal work of the thermoregulatory center and play the role of cooling; they can also stop the stimulation of nerve endings by pain-causing substances and achieve the role of pain relief. At present, the commonly used clinical antipyretics are: aspirin (acetylsalicylic acid), Anacin, paracetamol, Bamil (water-soluble aspirin effervescent tablets), Tylenol oral solution, pediatric albenzene tablets (aspirin phenobarbital), etc. There are many drugs and widely used. In the choice of drug treatment, it is further divided into pediatric and adult medication. Children must be careful with medication, the dosage will cause a lot of sweating, resulting in dehydration and weakness, which is not conducive to recovery. 3, common clinical adverse reactions As is known, most of the antipyretic and analgesic drugs are over-the-counter drugs, available in pharmacies, easy to buy, and people can use them directly from pharmacies. Therefore, the abuse of antipyretic and analgesic drugs is common in daily life, such as people encounter headache and brain fever, or toothache, joint pain, back and leg pain, etc., and often take antipyretic and analgesic drugs by themselves to relieve temporary pain without medical consultation, but people often ignore the adverse reactions of the drugs. The adverse reactions of antipyretic and analgesic drugs are also many, clinical symptoms of adverse reactions: such as aspirin can cause the body’s anti-coagulant dysfunction, can cause gastric bleeding, prompting asthma attacks and other phenomena; Anacin has a strong antipyretic effect, but because the drug can make the body temperature drop too quickly, so that people sweat too much and easy to cause deficiency; anti-inflammatory pain although it has a certain antipyretic effect, but the incidence of allergic reactions is very high The incidence of allergic reactions is very high. In addition to the above phenomena, some antipyretic drugs have certain hepatic and renal toxicity and neurotoxicity, so it is important to pay attention to the dosage when using them. In summary, it is recommended that people with fever must be examined under the guidance of a doctor to clarify the cause, reasonably match the medication, and reasonably arrange the time of using antipyretics and the dosage of antipyretics according to the clinical symptoms, generally speaking, do not use them for more than 3 consecutive days. It is the responsibility and duty of every medical worker to use antipyretic drugs reasonably, reduce adverse reactions and ensure people’s health, therefore, clinical research on antipyretic drugs is necessary.