Antipyretics are so common, but few people know how to use them properly. Fever is often caused by a bacterial or viral infection that produces a thermogenic agent that shifts the temperature setting point upward. Antipyretics are commonly used as a family medicine box, with non-steroidal antipyretics and analgesics such as acetaminophen and ibuprofen, and are commonly available in oral tablets, liquid preparations and topical suppositories. Although antipyretics are mostly over-the-counter (OTC) drugs that people can buy and use at pharmacies, there is often irrationality in their use due to the lack of guidance from physicians or pharmacists. Fever is one of the body’s self-defense mechanisms, so it is inappropriate to use antipyretic drugs immediately when you have a fever. When the body temperature is lower than 38.5℃, fever will make the body temperature rise, metabolism speed up, immunity enhance, which is not conducive to the survival of pathogenic microorganisms, and thus has a certain protective effect on the body, generally do not need to take antipyretic drugs, can use physical cooling therapy such as wet towel wipe, alcohol wipe, ice compress and other methods to cool down, while the appropriate amount of more water to accelerate metabolism, and thus help reduce fever. When the body temperature is higher than 38.5 ℃, metabolism too fast will lead to a significant increase in body consumption, serious cases may even coma, liver and kidney function damage, children may appear high fever-like cramps, convulsions, neurological damage and other adverse consequences, at this time need to take antipyretic drugs, if necessary, combined with physical antipyretic therapy, but also drink more water. Generally, antipyretics take effect in about 30 minutes to 2 hours, with a medication interval of 6-8 hours, the shortest interval being no less than 4 hours, and no more than 4 times in 24 hours. Fever reduction needs a process and should not be too fast, generally when the body temperature drops to below 38.5℃. If you take antipyretic drugs several times within a short period of time, it will often cause dehydration and deficiency due to heavy sweating, and it may also increase the toxic side effects of antipyretic drugs and cause damage to liver and kidney functions. Therefore, it is important to remember that antipyretic drugs should not be taken repeatedly within a short period of time. Try to use one antipyretic drug to reduce the risk of adverse reactions after combining drugs and to facilitate the tracing of the root cause in case of adverse reactions. For example, taking acetaminophen with the fever-reducing ingredient acetaminophen day and night to relieve cold symptoms, and then taking acetaminophen controlled-release tablets (Tylenol) may result in overdose due to repeated dosing. For children, acetaminophen or ibuprofen, which has fewer side effects, is generally preferred as a fever reducer. If vomiting or persistent high fever occurs with one drug, consider switching to another after 4 or 6 hours. Antipyretics as a symptom relieving drug does not eradicate the cause of the fever. Because of its hepatic and renal toxicity and neurotoxicity, it is generally recommended that antipyretics be used for no more than 3 consecutive days. If the fever persists for more than 3 days and cannot be relieved by medication, please go to the fever clinic of the hospital for examination.