Babies always have fever, consider infection factors, systemic diseases, as follows: 1. Infection factors: the main reason to consider factors such as infection, some are viral infection, bacterial infection or mycoplasma infection, in terms of treatment if there is no timely control of pathogenic infection, it will lead to recurrence of symptoms. 2. Systemic diseases: caused by some systemic diseases, such as hematological diseases or immunodeficiency, can lead to abnormalities in the body’s immune system, which can easily lead to pathogenic invasion and fever symptoms. Therefore, children always have fever and must be ruled out by pathogen detection, immune system detection and blood system related tests. Only when the cause is clear can we use the right medicine to relieve the symptoms of fever.