3-year-old baby fever when the whole body fever may be due to infection or immune system diseases, need to clarify the cause of the disease to take targeted treatment, such as anti-infection treatment, the application of gammaglobulin and hormone treatment. At the same time, the fever should be reduced actively. 1. Infection: bacteria, viruses can cause the baby fever when the whole body fever, according to the cause of infection to use anti-infection drugs such as bacterial infections can be used antibiotics such as amoxicillin, viral infections such as cytomegalovirus infections can be used to ganciclovir and other treatments. 2. Immune system diseases, such as Kawasaki disease, may have generalized fever and can be treated with aspirin, immunoglobulin, glucocorticoids and other drugs. In addition to allopathic treatment, but also according to the baby’s specific temperature for heat treatment, such as body temperature does not exceed 38.5 degrees, can take physical cooling, such as body temperature more than 38.5 degrees, you can follow the doctor’s advice to take ibuprofen and other antipyretic drugs to reduce fever. 3-year-old baby fever when the whole body fever, there may also be other reasons, should promptly consult a doctor, under the guidance of the doctor to use the relevant drugs for treatment.