Diarrhea and fever in babies can be caused by two factors. First, infants with immature gastrointestinal tract and immune system are very susceptible to bacterial or viral attacks, which can cause diarrhea and systemic symptoms of infectious poisoning, i.e., fever and malaise. Secondly, diarrhea in infants can lead to a high loss of body water and a decrease in effective circulating blood volume, which in turn can cause fever. At the same time, the child may be accompanied by more obvious symptoms of dehydration, including dryness of the infant’s skin and mucous membranes, sunken fontanelle, reduced tears and urine, or even no tears and no urine. In case of fever and diarrhea, the first step is to clarify the cause, and a hospital visit is necessary, which requires laboratory tests for blood and stool routines. If it is bacterial diarrhea, active anti-infection treatment is required. The main manifestation of bacterial diarrhea is mucus-like stool or mucus-purulent-blood stool. If the symptoms are not severe, oral antibiotics can be administered; if the symptoms are severe or accompanied by moderate or severe dehydration, intravenous antibiotics and intravenous rehydration therapy are required. In addition, microecological therapy can also be administered, such as intestinal probiotics or gastrointestinal mucosal protectors like montelukast. Symptomatic treatment is also important. If the fever exceeds 38.5 degrees Celsius, oral ibuprofen combined with physical cooling can be used to reduce the fever; if the fever is lower than 38.5 degrees Celsius, physical cooling can be used.