Fever (AAP)

Your child’s normal temperature will vary with his age, activity and the time of day. Infants tend to have higher temperatures than older children, and everyone’s temperature is highest between late afternoon and early evening, and lowest between midnight and early morning. Ordinarily, a rectal reading of 100 degrees Fahrenheit (37.8 degrees Celsius) or less, or an oral reading of 99 degrees Fahrenheit (37.2 degrees Celsius) or less, is considered normal, while higher readings indicate fever.

By itself, fever is not an illness. In fact, usually it is a positive sign that the body is fighting infection. Fever stimulates certain defenses, such as the white blood cells, which attack and destroy invading bacteria. However, fever can make your child uncomfortable. It increases his need for fluids and makes his heart rate and breathing faster.

Fever most commonly accompanies respiratory illnesses, such as croup or pneumonia, ear infections, flu, severe colds and sore throats. It may also occur with infections of the bowel or urinary tract, and with a wide variety of viral illnesses.

Whenever you think your child has a fever, take his temperature with a thermometer. Feeling the skin (or using temperature-sensitive tape) is not accurate, especially when the child is experiencing a chill. If your child is less than 3 years old, take his temperature rectally with a mercury rectal. If he is older, he probably can cooperate well enough for you to take his temperature orally, but make sure the thermometer remains in place for at least two minutes.

When to Call the Pediatrician for Fever

If your child is 2 months or younger and has a rectal temperature of 100.2 degrees Fahrenheit (37.9 degrees Celsius) or higher, call your pediatrician immediately. This is an absolute necessity. The doctor will need to examine the baby to rule out any serious infection or disease.

You may need to notify the doctor if your child is between 3 months and 6 months and has a fever of 101 degrees Fahrenheit (38.3 degrees Celsius) or greater, or is older than 6 months and has a temperature of 103 degrees Fahrenheit (39.4 degrees Celsius) or higher. Such a high temperature may indicate a significant infection or dehydration, which may require treatment. However, in most cases your decision to call the pediatrician also will depend upon associated symptoms, such as sore throat, earache or cough. If your child is over 1 year of age, is eating and sleeping well, and has playful moments, there usually is no need to call the doctor immediately. You may wait to see if the fever improves by itself or with home treatment methods. If a high fever persists for more than 24 hours; however, it is best to call even if there are no other complaints or findings.

If your child should become delirious (acts frightened, “sees” objects that are not there, talks strangely) during his fever, call your pediatrician, particularly if this has not occurred before. These unusual activities probably will disappear when the temperature returns to normal, but the doctor may want to examine the child to make sure they are a response to the fever and not something more serious, such as an inflammation of the brain (encephalitis).

Excerpted from Caring for Baby and Young Child: Birth to Age 5, Bantam 1999