Back to Home Skip Navigation LinksHome Knowledge Center What is a Fever?
Back to Knowledge Center Results

What is a Fever?

​​​​​​​​​​A fever means the body temperature is above normal. Your child has a fever if:

  • Rectal, oral, axillary, ear or temporal artery temperature is over 100.4 F/38 C. (Ear/tympanic temperature method is not reliable for children under 5 years of age.)

A fever can’t always be detected by feeling your child’s forehead. Please take your child’s temperature before calling your doctor. The accurate data helps us to determine how to treat your child. The “gold standard” for infants and young children is still the rectal temperature.

The body’s temperature is usually higher in late afternoon and evening. Increased temperatures can be caused by exercise, heavy clothing, a hot bath or hot weather. Warm food or drink can also raise the oral temperature. If you suspect such an effect on the temperature of your child, take his temperature again in a half hour.

What is the cause?

Fever is a symptom, not a disease. It is the body’s normal response to infections. Fever helps fight infections by turning on the body’s immune system. Most fevers (ranging from 100 F to 104 F) that children get are helpful, not harmful. Most are caused by viral illnesses such as colds or the flu, but some are caused by bacterial illnesses such as strep throat or ear infections. Teething does not cause significant fever.

When are fevers dangerous?

Fevers with infection do not cause brain damage. Infections like encephalitis and meningitis may be associated with brain damage, but the damage is due to the infection, not the actual fever. Only body temperatures over 108 F can cause brain damage. The body temperature goes this high only with extreme environmental temperatures (if a child is confined in a closed car in hot weather), heat stroke or reactions to anesthesia.​

While all children get fevers, only four percent develop a brief seizure from the fever. This type of seizure is generally harmless, but a child who has a febrile seizure should always be checked by a healthcare provider. If your child has had high fevers without seizures, your child is probably not going to have one.

When should I call my child’s healthcare provider?

Observation of other signs and symptoms of a sick child are often more important than the height or duration of the fever.


  • Your child is less than 3 months old.
  • The fever is over 104 F (40 C) and has not improved two hours after giving fever medicine.
  • Your child looks or acts very sick (fever along with severe headache, confusion, stiff neck, trouble breathing, rash or refusing to drink).

Call within 24 hours if:

  • Your child is 3 to 6 months old (unless the fever is due to an immunization shot).
  • Your child has had a fever longer than 24 hours without an obvious cause or location of infection AND your child is less than 2 years old.
  • Your child has had a fever for more than three days.
  • The fever went away for over 24 hours and then returned.
  • You have other concerns or questions.

Managing the Fever

Remember that the fever is helping your child fight the infection. Fevers only need to be treated with medicine if they cause discomfort. This usually means fevers above 102 F or if your child is uncomfortable.


Children older than 2 months of age can be given acetaminophen (Tylenol). The dose is dependent on the weight, so use the chart attached. Never give more than five doses in any 24 hour period. The infant drops were removed from pharmacies in 2011 due to overdoses resulting from confusion between the drops and suspension. If you are purchasing the suspension, the four-ounce bottles are the most cost- effective.


Ibuprofen (Advil, Motrin) is approved for infants over 6 months of age. One advantage ibuprofen has over acetaminophen is a longer lasting effect (six to eight hours instead of four to six hours). The dose is dependent on weight, so use the chart attached​.

Avoid aspirin:

Doctors recommend that children (through age 21 years) do not take aspirin for fevers. Aspirin taken during a viral infection, such as chickenpox or flu, has been linked to a severe illness called Reye’s syndrome. If you have teens, warn them to avoid aspirin.


Sponging a normal child is only indicated if the fever may be harmful (temp over 105). If your child has had a febrile seizure, see the febrile seizure discussion below, as sponging may be indicated for lower temperatures. Unless the temp is over 105, give acetaminophen or ibuprofen first and retake the temperature 20-30 minutes later. If the fever persists, then you may sponge the child in lukewarm water for about 45 minutes. If you put the child in the water before you give the acetaminophen or ibuprofen, the brain’s thermostat is still turned up, and you will only cause more chilling and more constriction of blood vessels.

Febrile Seizures:

Some children will have a brief seizure when the temperature goes up rapidly. This is rare, but if this happens, call your pediatrician or take your child to an emergency room, as it may indicate the beginning of a very serious illness.

If your child has already had a seizure with a fever, then it is recommend that when you notice a fever in your child, administer the ibuprofen every six hours until the fever has been gone for 24 hours. Add acetaminophen and/or sponge your child when it appears that the temperature will reach the point where it has caused seizures before.

  • When to Treat Your Baby's Fever

    So if your baby is under 3 months of age we'd really rather not treat fevers at that ​age, just because we don't want to mask a fever.

    Those babies under 3 months of age are a little bit unpredictable. They don't have a super mature immune system. And if you think they're a little fussy or have a fever and you start giving lots of Tylenol or acetaminophen you might be masking something bigger. So we want to make sure.

    Give us a call first, and we'll check the baby over and let you know. Yep. It's safe to give Tylenol now.

Illness and Injury;Cold and Flu Pediatrics