Fever in a child with a respiratory problem

Fever is the body's normal and healthy reaction to infection and other illnesses, both minor and serious. Most fevers help the body fight infection.

Viral and bacterial respiratory infections can cause high fevers in children.

• Viral infections.
  • Viral infections cause most upper respiratory infections. Sore throats, colds, croup, and influenza (flu) are common viral illnesses in babies and children. These infections are usually mild and go away in 4 to 10 days, but they can sometimes be severe. Antibiotics are not used to treat viral illnesses and cannot decrease the length of the illness.
  • Viral lower respiratory infections may be mild, similar to upper respiratory infections. An example of a possibly serious viral infection is bronchiolitis. Up to 10% of babies and children with viral infections of the lower respiratory system (such as those caused by respiratory syncytial virus, or RSV) may develop severe blockage of the air passages and require hospitalization for treatment.
• Bacterial infections.
  • The most common sites for bacterial infections in the upper respiratory system are the ears, sinuses, and throat. Whooping cough (pertussis) is an example of an upper respiratory bacterial infection.
  • Bacterial infections. Bacterial pneumonia may follow a viral illness or be the first sign of infection. In babies and small children, the first evidence of infection is often rapid breathing, irritability, decreased activity, and poor feeding. Antibiotics are effective against bacterial infections. Tuberculosis is a less common bacterial infection of the lower respiratory system.

A fever that lasts up to 4 days is usually not a concern, especially if it comes and goes and gradually reduces over time.