9 months baby fever 38.5 degrees, may be bacterial infection, viral infection, mycoplasma infection and other causes. You need to use ibuprofen to reduce fever in time and use cefaclor dry suspension, azithromycin, etc. for treatment. 1. Bacterial infection: 9 months baby fever 38.5 degrees, may be caused by bacterial infection. To reduce the fever as soon as possible, you can use ibuprofen and other drugs to reduce the fever treatment, but also to use cefaclor dry suspension for anti-infection treatment. 2. viral infection: 9 months baby fever 38.5 degrees, may also be caused by viral infection, usually do not need to use antiviral drugs. However, you need to ensure indoor ventilation and avoid going to crowded places. If the general state is good, you can warm water baths and other physical cooling, if necessary, oral ibuprofen, acetaminophen and other drugs to reduce fever. 3. mycoplasma infection: 9 months baby fever 38.5 degrees, there may be mycoplasma infection caused. In addition to the use of reasonable fever reduction, but also need to be treated with azithromycin dry suspension and other macrolides. When the child has a fever of 38.5 degrees, parents should take the child to the doctor in a timely manner, and actively carry out the treatment of fever, but also to find the cause of the fever, according to the cause of targeted treatment, not unauthorized use of drugs.