There are many reasons why children have diarrhea after a fever, but two common causes are gastrointestinal colds and gastrointestinal dysfunction due to fever. 1. Gastrointestinal cold: The child may have a fever and diarrhea due to inflammation of the gastrointestinal tract caused by a poor diet or lack of hand hygiene. The child may have a bacterial infection or a viral infection. 2. Gastrointestinal dysfunction due to fever: children may have gastrointestinal dysfunction after having a fever, which may lead to indigestion and diarrhea. After going to the hospital to check the child’s stool routine is usually not abnormal. Children with fever diarrhea, parents need to take the child to the hospital after examination, to identify the cause, under the guidance of the doctor to use medication.