If your child has a fever, the chances are high that one of the following conditions caused it: Viral Infection This is the most common cause of fever in children and does not require antibiotics. Your child will need antibiotics for treatment. What are the symptoms that my child may have a fever? If your child takes blood thinner medicine, always ask if NSAIDs are safe for him or her. Your child may feel warm or hot. NSAIDs can cause stomach bleeding or kidney problems in certain people. Your child may seem fussier, less hungry, and thirstier. Your child may not be as active or talkative as usual. Here are some of the causes why your child has a fever: Bacterial sepsis is a condition in which bacteria enter your child's bloodstream and causes an infection in the kidneys, lungs or other organs. NSAIDs , such as ibuprofen, help decrease swelling, pain, and fever. This medicine is available with or without a doctor's order.