What is the most common cause of fever in children?

The most common cause of fever in children is viral infections. This is largely due to the fact that children are exposed to a wide variety of viruses during their early years, particularly in settings such as daycare and school. Viral illnesses, such as respiratory infections (like the common cold or influenza), gastrointestinal infections (such as rotavirus), and others like roseola and hand-foot-and-mouth disease, frequently lead to fever as part of the body's immune response to the viral presence.

The body's response to viral infections typically includes the release of pyrogens, which promote fever. This increase in body temperature serves as a defense mechanism that helps to inhibit viral replication and enhances the effectiveness of the immune response.

Other factors, such as bacterial infections or allergic reactions, do cause fever, but they are generally less common than fever due to viral infections in the pediatric population. Fungal infections are rare among children and are not typically a frequent cause of fever in this age group.