A three-month-old baby with a fever of 37.8°C can be physically cooled, with dynamic monitoring of temperature and use of acetaminophen to reduce fever if necessary, as well as identifying the cause of the fever and administering medication. Fever is a more common symptom of pediatrics, usually considered axillary temperature over 37.3 ℃ for fever, for 3-month-old babies, the temperature is 37.8 ℃ for low fever, need to be through the warm water wipe forehead or antipyretic stickers, as appropriate, warm baths and other ways to increase the dissipation of heat for physical cooling, and need to dynamically monitor the body temperature. Some babies through physical cooling temperature can be reduced to normal, but if the baby physical cooling effect is not good, there is a persistent increase in temperature, such as temperature over 38.5 ℃, need to use acetaminophen for symptomatic antipyretic. At the same time need to identify the cause of fever, such as acute upper respiratory tract infection, can appear the above symptoms, the presence of bacterial infection need to use antibacterial drugs (such as cefaclor) anti-infection treatment. The above drugs should be used under the guidance of a physician, avoid self-medication. If your baby has fever, it is recommended that you actively seek medical attention and be guided by a specialist.