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What Temperature is a Fever

What is a Fever

Fever is a rise in a person’s body temperature above normal. Healthy humans have body temperatures between about 97.5 °F and 99 °F (36.7 °C and 37.7 °C). Average human body temperature, or what most people call “normal” temperature, is about 98.6 °F or 37°C. Body temperature changes normally over the course of the day. Most people’s temperature is coolest in the early morning hours before they wake up, and is warmest in mid-afternoon. Body temperature is also quite different depending on where in the body one measures it. Because of all of this variability, most doctors do not refer to a person’s having a significant fever unless their “core” temperature (taken with a rectal or oral thermometer) is higher than about 100.4 °F or 38°C. In newborns under the age of 3 months, doctors often tend to be a little more cautious, and view anything above “normal” as a fever. In fact, in these very young babies, serious illnesses can cause the body temperature to go below normal.

Fever is a person’s normal response to an infection or irritation. Strong evidence suggests that when people have infections, their immune system works better at a slightly higher temperature to destroy the germs that are causing the infection. At the same time, the germs’ own systems may not work quite as well at a higher temperature, which can give the immune system an additional advantage. Of course, too much fever is not a good thing – fevers make people feel miserable, hot, and cranky. Many people say that their bones and joints ache, their eyes hurt, and even complain that their “hair hurts” during a fever. Infants and children below the age of about 4 years tend to run much higher fevers than older children and adults. Since younger children can’t describe their discomfort, they are often whiny, or fussy, and their appetites are usually below normal.

Many people firmly believe that fever causes brain damage. Fever does not cause brain damage. This idea may come from times long past when fever often meant a serious infection like meningitis. Meningitis and other serious bacterial infections can indeed cause brain damage. Fortunately, these conditions are quite rare now, and today we know that any brain damage that follows a fever is the result of whatever caused the fever, not of the fever itself. We’ll say it again, this time for the in-laws: Fever does not cause brain damage.

What is the biggest concern?

Our two biggest concerns in infants and children with fever is finding out why they have the fever, and keeping them comfortable until the illness clears up and the fever goes away. While fever itself is not dangerous, and most of the conditions that cause fever are not dangerous, there are a few that are. In general, younger children tend to be more likely to have more serious infections with fever. Doctors will usually do blood and urine tests on any baby younger than 2-3 months old with a temperature above 100.4 °F (38.0°C). Depending on the results and on how the baby looks, they may consider other tests, like a lumbar puncture (spinal tap). Please do not be afraid to take your child to the doctor because of the possibility of tests, however. Your doctor should feel comfortable discussing your concerns with you, and most doctors will agree to a compromise arrangement if parents feel very strongly, so long as the child does not appear ill.

In older children doctors usually feel more comfortable doing fewer tests or none at all, depending on the child’s other symptoms and appearance. In addition to a physical examination, which very often reveals the cause of the fever, doctors commonly check urine and blood, throat cultures, and chest X-rays as they search for a treatable source of infection.

Once the source of the fever is identified (or the doctor decides that the fever does not indicate an infection that can or needs to be treated), we focus on the child’s comfort. As we mentioned, fever is very uncomfortable, and can interfere with the child’s sleep, appetite, and activity. It can also wear out and worry the parent. We aim to reassure parents, grandparents, and other family members so that they don’t add to their own stress by worrying too much about fever.

Fever treatment

In most cases, doctors don’t find any cause of infection with a bacterial organism. This means that most cases of fever are not treated with antibiotics. Except in very young infants, most doctors prefer to avoid using antibiotics unless they know that the cause of the fever is a bacterium that the antibiotics will kill. If your doctor makes a diagnosis of a bacterial infection and prescribes antibiotics, please be sure to give each dose as close to on time as you can. It’s also important to give every dose – in other words, don’t stop when the child “seems better.” This can produce germs that are “resistant” to the antibiotic and can be much harder to treat later on.

To treat the fever itself, most doctors recommend using an anti-fever medicine such as acetaminophen (Tylenol®) or ibuprofen (Advil® or Motrin®) in children over 3 months. Check with your doctor about using these in younger babies. Fever is not dangerous, but it can make the child uncomfortable. If your child seems comfortable there is no reason to give any medication just for fever. Please NEVER give aspirin to a child with a fever unless you have first talked with your doctor. Aspirin is a good medicine but it can cause serious complications in certain viral illnesses.

In addition to medication, you can try to bring down a fever by giving your child a lukewarm bath. Have your child sit in the tub with lukewarm water to the hips only, and gently rub a wet washcloth over the baby’s back, chest, and head. As the lukewarm water slowly evaporates, it will take heat away from the baby at the proper rate. If the baby starts to shiver or gets “goose bumps,” please take him or her out and dry him or her off. Shivering and goose bumps will actually increase the body temperature.

For the same reasons, cold baths are not a good idea – they are very uncomfortable and they can make the baby shiver and increase his or her body temperature. Please NEVER give a baby or child an alcohol bath or rubdown. This can not only bring the temperature down too fast and cause shivering and goose bumps, but it can also cause alcohol poisoning when the baby’s skin absorbs the alcohol.

A quick word about treating fevers in general: although we use the phrase “control the fever” when we talk about treating it, this can be a little misleading. Your child’s body is trying to control his or her body temperature and keep it at the right point to help it kill the germs. Some children respond very readily to the anti-fever medicines, and others don’t. Please don’t feel that you are a “bad parent” because you can’t “control” the fever. Please especially avoid giving extra doses of medicine if the fever does not respond – this is always much more dangerous than the fever itself. Don’t set yourself up to believe that you “must control the fever,” because then you might feel frustrated or even panic if you can’t. Watch your child carefully, and try some of the other cooling things suggested above. If all else fails, please call your doctor – but remember that you aren’t failing as a parent, and the fever won’t just keep climbing and climbing!

Dangerous Fever Symptoms

As we’ve said several times in this Aftercare Instruction, fever (under 106 °F or 41.1 °C) is not dangerous, but it is uncomfortable and can be the sign of a serious infection. In a small number of children it can cause seizures. Here are some things to look out for when your child has a fever:

  • Temperature over 102.4 °F or 39 °C in a baby less than 2 years old who has not yet seen the doctor for this illness
  • Temperature over 100.4 °F or 38 °C in a baby less than 3 months old
  • Shaking chills that last more than five minutes
  • Seizure (involuntary body movements with loss of consciousness)
  • Severe headache and/or stiff neck
  • Vomiting more than 2-3 times, or vomiting that gets worse rather than better over time
  • Severe abdominal pain (“tummy ache” can be normal with fever if it doesn’t last more than a few hours)
  • Any new rash that your doctor has not seen in your child with this illness.
  • Any rash that is purple, black, or like tiny red dots that you can’t feel when you slide a finger over them. The red spots may or may not disappear when you press on them.
  • Worsening of any other symptoms that came along with the fever, such as cough,sore throat, etc.
  • Swelling or redness of any body part that was not present when the fever started

If any of these occur, please be sure to call your doctor’s office right away. If your child has any of the items listed above in bold print, please go directly to the emergency room.

Other points of concern

Despite what many people think, normal fevers in children do not cause brain damage. Fever over 106 °F or 41.1 °C can cause some problems, but even these are only important if the fever lasts several hours at this high level. Fevers this high are very unusual, but do of course see your doctor if your child gets a fever that high.

Please don’t be afraid to let your doctor or nurse know if you have trouble reading a standard glass thermometer. They are really very hard to read, and most doctors’ offices no longer use them. If possible, you might try to get an electronic digital thermometer. These are much easier to use and to read. Please follow the directions carefully and remember to discard the protective cover after each use.

Other Conditions that Might Be Present with a Fever

Many people worry about seizures with fevers. These so-called “febrile seizures” are unusual, but they do happen to about one in twenty children with high fever. You can read about them in our Aftercare Instruction on Febrile Seizures.

Again, as we have stressed – the fever itself is not the illness. Rather, something (usually a bacterium or a virus) is causing the fever, and it will be important for you to discuss with your doctor what that cause might be, and whether it should be treated.