Fever reduction for babies should be both physical and physiological. Fever is one of the most common symptoms in infants and children, and young parents who are new parents are often at a loss as to what to do with their baby’s fever. So why do babies have fevers, why do they recur soon after the fever subsides, and what happens to the baby’s body when they have a fever? How should we deal with it is scientific and reasonable? To understand this problem, we still need to do some homework, starting with the principle of fever! Under normal circumstances, the body heat production and heat dissipation in a state of dynamic balance, maintaining a basic constant body temperature. Humans are constant temperature animals, we eat a variety of food every day, part of which will produce heat to maintain our basic body temperature, the basic body temperature for most normal people is about 36.5 ℃. At the same time, we lose heat at any time, through radiation, conduction, convection and evaporation of heat from the body surface. Under normal circumstances, the body is in a dynamic balance between heat production and heat loss, maintaining a basic constant body temperature. When a baby is sick, the body may become feverish, why is this? There are very many reasons for fever, and we will take here as an example the fever caused by the most common infection in babies. When the virus invades the baby’s body, the virus, as an exogenous pyrogen, causes the thermoregulatory center in the hypothalamus to be upregulated, so that the body produces more heat than it dissipates, and the body temperature rises to a new equilibrium point. The body will consider a higher than normal temperature to be the appropriate temperature, let’s assume 39°C. At this time, the center will send instructions to the body to increase heat production (e.g., chills: involuntary movement of skeletal muscles increases heat production during fever) and reduce heat dissipation (e.g., less sweating, less sweat gland secretion and thus less evaporation; cold hands and feet: peripheral capillary constriction reduces heat dissipation), so that the body temperature reaches 39℃, a level considered normal by the brain, to produce a new equilibrium. During the phase of rising body temperature, the baby usually feels cold. From another point of view, fever is actually the baby’s body immune forces to wage a war against pathogens, foreign invaders, so to speak, without the immune response, there is no fever, so it can be seen that fever is actually beneficial. This means that the body’s immunity is at work. However, the fever process is difficult for the baby, the fever heart rate and respiration increase, metabolic rate increases, the urine volume will increase at the beginning (which is related to the increase in metabolism), and the high metabolic rate for a long time is a test of the body’s ability to withstand. It is with this in mind that we want to keep the fever in an appropriate range. This is what we are talking about. How to reduce fever is reasonable and reliable. Fever reduction should be in accordance with both the laws of physics and physiology. Ultimately, nothing can be divorced from the basic laws of physics, even for such a complex organism as life, but at the same time, life is, after all, organic and cannot be cooled down exactly according to physical methods. If a piece of red-hot iron we want to recede its high temperature to throw it in the water, this is in line with the laws of physics. But for the human body, this is in line with the laws of physics (must be able to reduce fever) but not physiological (will lead to more serious problems). 1, in fact, is not in line with the laws of physics, while doing contradictory things, on the one hand, wear very thick, not conducive to heat dissipation, because this will reduce radiation heat dissipation, conduction heat dissipation, convection heat dissipation, evaporation heat dissipation, the baby’s body temperature will not be easy to come down. The contradictory practice is to try to increase heat dissipation at the same time by applying antipyretic patches and rubbing alcohol on the heart of the hands and feet. But the forehead and hands and feet body surface area is small, can dissipate the heat is very little. 2, is currently a more common overkill for physical cooling practices, the problem with this approach is that it is consistent with the laws of physics but not with physiology. If the baby is shivering and afraid of cold during the fever, the body temperature is actually rising rapidly, and this time the thermoregulatory center thinks that the current body temperature is low, so it will mobilize the whole body organs to increase heat production and reduce heat dissipation. So the baby will be shivering (increase heat production), cold hands and feet (reduce heat dissipation), when trying to force physical cooling to lower the body temperature is not physiological, the effect will not be good, strong cold stimulation may even induce the baby convulsions. How to do? 1, physical cooling to choose the right time, try to avoid the rapid rise in body temperature period. At this time the baby often behaves as cold hands and feet, and even a little purple, a little older baby will have obvious chills. This time rashly take physical cooling, especially strong physical cooling is not in line with the physiology, may induce baby chills response aggravated, peripheral capillary constriction aggravated or even induced convulsions. 2, is to try to choose a mild physical cooling method. For example, do not cover the quilt, less clothing, take off the hat, these are relatively mild physical cooling methods. If it is winter, appropriately raise the room temperature to 20 + ℃, to reduce the large temperature difference to the baby’s discomfort and stimulation. In the case of mild ways can not solve the problem, the temperature continues to exceed 39 ℃, which is two options, 1. take antipyretic drugs. 2. continue physical cooling. The first is more reasonable (our country and other countries guide a consensus are so), unless the baby still high fever does not go away after taking medicine. At this time of physical cooling can choose warm towels applied to the groin, armpits, warm water bath or apply bath, water temperature and the usual baby bath the same temperature or slightly lower, should not soak in the bathtub, but the best shower or bath, so that the water evaporation process to take away the heat, otherwise counterproductive. In addition, during the bathing process, if the baby has obvious discomfort crying, or even chills, please immediately stop this physical cooling method. 3, the appropriate time to use antipyretic drugs. The common view in China is that it can be used if it is above 38.5℃, and the consensus in the United States is 39℃. Of course this value is flexible. How to grasp it? I think the important thing is to look at the baby’s mental state, some baby’s temperature fever to almost 39 ℃, still behaves more or less normal, this time you can also temporarily do not take antipyretic drugs but use some mild physical cooling. Some babies only have a temperature of 38 ℃, but they feel in a bad state, crying, older babies may also be described as headache, body aches and pains, this time there is no need to adhere to the value of 38.5 ℃, the baby can take antipyretic medicine can not only reduce fever can also relieve pain and improve the baby’s comfort. Antipyretic drugs are currently recommended (WHO, APP and Chinese guidelines and consensus are recommended for both) for children are ibuprofen and acetaminophen as first-line drugs. They are safe and effective under normal use, so you don’t have to worry about side effects if you take them according to the instructions. Of course, overdose is another story, leaving the dose to talk about side effects is meaningless, the bun non-toxic can also be held up to death. 4, appropriate to drink more water, maintain the baby urine volume and the usual equivalent or slightly more. Baby fever through the body surface evaporation and breathing out of the water will be a lot more than usual, but also for the metabolism, baby in the early stages of fever urine volume will also increase significantly, so the appropriate supplemental water is an important way to maintain the stability of the baby’s internal environment. If there is not enough water, the baby’s body heat will not be easily dissipated through evaporation of heat and other means, and the amount of urine will be significantly reduced. Severe cases lead to hypertonic dehydration, which is not only detrimental to fever reduction, but also to the stability of the baby’s internal environment, adding chaos to the baby’s immune system and not conducive to disease recovery. But how to drink water as appropriate? Personally, I think it is appropriate to maintain the baby’s urine volume slightly more than usual, generally speaking, the baby fever water loss to a certain extent will appear obvious thirst, older babies will take the initiative to ask for water to drink, it should be noted that small babies, thirst may only cry, mom and dad a little to consider whether it is thirsty. Of course, the more water you drink, the better. The dilution function of the baby’s kidneys is smaller than that of adults, so drinking too much water can put a burden on the baby’s kidneys and cause water intoxication in serious cases. Occasionally, we encounter parents force-feeding water to their babies in the clinic, resulting in swollen eyes. 5.Define the cause of the disease and actively remove the cause. Fever is only a clinical symptom, not a disease, so remove the cause of the disease in order to finally control the temperature.