Fevers occur commonly during childhood. Most are due to the body's defense against minor infections and resolve without consequence. However, fevers that reach high temperatures or last for more than three days are more likely due to a serious illness. High fevers that last for five days warrant an evaluation by a health care provider.
What is a high fever in healthy children?
The age of a child is an important factor for determining if a fever is high. Although there is not one definition for high fever, here are some guidelines for when to consult a health care provider:
• Infants younger than 2 months - Any fever reaching 100.4oF (38oC) rectally, regardless of the duration, is concerning and the baby should be seen immediately by a health care provider.
• Infants and toddlers, 2 months to 36 months – temperatures higher than 100.4oF (38oC) for more than 3 days or any rectal temperature higher than 102ºF (38.9ºC), • Children and adolescents, 3 years of age and older – 100.4oF (38oC) for more than 3 days or any temperature higher than 103ºF (39.4ºC)
What causes high fevers in children?
With some infections, fever may be present for 24 hours before other symptoms appear. An exception is roseola, where the fever may be high and persist for 3 to 7 days without other symptoms. However, usually the child is well appearing. Once the fever breaks, a rash appears and the infection resolves.
For most illnesses, fever is not the only complaint and the other symptoms help identify the illness.
Common causes of fever in children include: • Viral illnesses are the most common cause of fever for children and teens of all ages. Viruses may infect the intestines causing vomiting or diarrhea or the respiratory tract and cause the "common cold," ear infections, sore throats, and bronchitis. Real "flu" caused by an influenza virus usually occurs during the winter and is associated with abrupt onset of high fevers, as well as other symptoms such as cough, sore throat, muscle aches and feeling lousy.
Fevers with these illnesses usually last less than 5 days and can be managed at home with fever medications (such as acetaminophen or ibuprofen), rest and plenty of fluids.
• Bacterial infections are also common in kids. These include ear infections, sinus infections, sore throats caused Group A strep (the germ Streptococcus pyogenes), pneumonia, urine infections, or intestinal infections. Without proper antibiotic treatment, fevers may persist longer than 5 days.
• Other infections that may cause persistent, high fevers include tuberculosis, mononucleosis (nicknamed "the kissing disease"), and sexually transmitted diseases, such as herpes and HIV, and infections in travelers, such as malaria.
• Kawasaki Disease is a vasculitis (inflammation of the body's blood vessels) whose cause is unknown, but is thought to be an infectious agent. Afflicted children have fever for 5 days, and a collection of other symptoms including swollen lymph nodes, rash and inflamed mucous membranes. Kawasaki is more common in children younger than 8 years of age of Asian descent but can occur in any child.
• Non-infectious causes of fever include autoimmune disorders (such as rheumatoid arthritis, lupus and inflammatory bowel disease), malignancies such as leukemia, reaction to medications or vaccinations, and illicit drugs (such as cocaine and amphetamines).
• Contrary to common beliefs, teething does not cause high fevers.
Warnings and Precautions
Regardless of how high a child's fever is, if other concerning symptoms are present, promptly seek medical care. Examples of alarming symptoms include: • Difficulty breathing, • Stiff neck, • Unable to see, hear or speak, • New rash, • Lethargy, • Persistent crying or pain, or • Child isn't him/herself
In addition, if parents are concerned for any reason, they should consult with their health care provider.
For children and teens, illnesses that cause fevers are usually self-limited and not associated with high fevers or fevers that last longer than 3 days. If your child has a high fever or a fever that last longer than 5 days, consultation with your doctor is warranted.