Children run fevers frequently, but that isn't necessarily the sign of a major problem. Most fevers stem from minor illnesses and go away on their own after a few days. Others signal a need for treatment, especially if your child has a fever that lasts more than a few days or goes above 103.5 degrees Fahrenheit. Any temperature when taken orally that is above 99.5 degrees or 100.4 degrees rectally is considered a high fever in a child.
Viral Infections
Viral illnesses are a common source of fevers in children. Viral infections include the common cold, the flu and chickenpox. Most viral illnesses are not dangerous and many only produce a mild fever. However, even some minor illnesses can boost your child's temperature to high levels for short periods of time as her body fights off the virus; however, the high degree of fever doesn't indicate the severity of the disease.
Bacterial Infections
Bacterial infections stem from an invasion of pathogenic bacteria into the body. Pneumonia, ear infections, sinus infections, strep throat and urinary tract infections are all bacterial illnesses. A course of antibiotics typically kills off the invading bacteria and reduces the fever. In some cases, a bacterial infection can spread into the bloodstream or brain. If this occurs, the body usually responds with a very high fever; the child might need emergency care.
Immunizations
Your child's routine vaccinations can sometimes cause a slight fever in the hours or days after the immunization. These typically do not last longer than two days and are generally mild. This is not an indication of a poor response to the vaccine, but simply an indication that your child's immune system is responding and building up immunity to the disease the vaccine is designed to protect her against.
Teething
Some children develop a fever during teething, although this is usually under 101 degrees. If your child's fever runs higher than this during teething, there is likely to be some other cause. You should contact a doctor to determine whether an illness is present. The cause of teething fevers is unknown, although inflammation of the gums as the teeth break through could be responsible.
Rare Causes
A child with an autoimmune disorder, such as juvenile arthritis or Crohn's disease, might develop a fever due to the inflammation caused by his condition. Childhood cancers, including leukemia and lymphoma, can also cause a fever. Other potential causes of fever include blood clots and some medications, such as antibiotics, antihistamines or seizure medicines. All of these fever causes are rare, and most childhood fevers will stem from more mundane reasons.
