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Fever is the body's normal and healthy reaction to infection and other illnesses, both minor and serious. Fevers help the body fight infection. Fever is a symptom, not a disease. In most cases, fever means your child has a minor illness. Often you must look at your child's other symptoms to determine how serious the illness is. Although it may be scary when your child's temperature goes up, fever is not harmful.

Normal body temperature

The average normal body temperature is about 98.6°F (37°C). It usually rises during the day from a low of 97.4°F (36.3°C) in the morning to a high of 99.6°F (37.6°C) in the late afternoon. Each child has a normal temperature range that may be different from another child's. Mild increases to 100.4°F (38°C) can be caused by exercising, wearing too many clothes, taking a hot bath, or being outside in hot weather.

Fever

Temperature varies depending on how you take it. The most common ways to measure it are:

  • Under the tongue.
  • In the armpit.
  • In the rectum.
  • In the ear.

You can also use:

  • Forehead thermometers.
  • Pacifier thermometers.

Some methods may not be as reliable or accurate as others. For information about taking accurate temperatures, see the topic Body Temperature.

If you think your child has a fever but you are not able to measure his or her temperature, it is important to look for other symptoms of illness.

Children tend to run higher fevers than adults. The degree of fever may not indicate how serious your child's illness is. With a minor illness, such as a cold, a child may have a temperature of 104°F (40°C), while a very serious infection may not cause a fever or may cause only a mild fever. With many illnesses, a fever temperature can go up and down very quickly and often, so be sure to look for other symptoms along with the fever.

Babies with a fever often have an infection caused by a virus, such as a cold or the flu. Infections caused by bacteria, such as a urinary infection or bacterial pneumonia, also can cause a fever. Babies younger than 3 months should be seen by a doctor anytime they have a fever because they can get extremely sick quickly.

A fever in a healthy child is usually not dangerous, especially if the child does not have other symptoms and the fever goes away in 3 to 4 days. Most children who have a fever will be fussy and play less and may not eat as much as usual.

High fevers may make your child uncomfortable, but they rarely cause serious problems. There is no medical evidence that fevers from infection cause brain damage. The body limits a fever caused by infection from rising above 106°F (41.1°C). But outside heat—such as from being in a car that is parked in the sun—can cause body temperature to rise above 107°F (41.7°C), and brain damage can occur.

Childhood immunizations can reduce the risk for fever-related illnesses, such as Haemophilus influenzae type b (Hib) infection. Although no vaccine is 100% effective, most routine childhood immunizations are effective for 85% to 95% of the children who receive them. For more information, see the topic Immunizations.

Causes of fever

It is not unusual for a preschool-aged child to have 7 to 10 viral infections in a year. Each new viral infection may cause a fever. It may seem that a fever is ongoing, but if 48 hours pass between fevers, then the new fever is most likely from a new illness.

Common causes of fever include:

  • Viral infections, such as colds, flu, and chickenpox.
  • Bacterial infections, such as a urinary tract infection.
  • Immunizations.

Teething does not cause a fever. If a baby is teething and has a fever, look for other symptoms that may need to be evaluated.

A fever that increases quickly may lead to a fever seizure in some children. After a fever has reached a high temperature, the risk of a seizure is less. Fever seizures can be frightening to see, but they usually do not cause other problems, such as brain damage, intellectual disability, or learning problems. If your child has a high fever and a seizure, see the topic Fever Seizures.

Low body temperature

An abnormally low body temperature (hypothermia) can be serious, even life-threatening. Low body temperature may occur from cold exposure, shock, alcohol or drug use, or certain metabolic disorders, such as diabetes or hypothyroidism. A low body temperature may also be present with an infection, particularly in newborns, older adults, or people who are frail. An overwhelming infection, such as sepsis, may also cause an abnormally low body temperature.

Check your child's symptoms to decide if and when your child should see a doctor.

It can be hard to know whether you should call your doctor when your child has a fever, especially during the cold and flu season. The degree of the fever may not be related to the seriousness of the illness. The way your child looks and acts is a better guide than the thermometer. Most children will be less active when they have a fever.

If your child is comfortable and alert, is eating well, is drinking enough fluids, is urinating normal amounts, and seems to be improving, home treatment without medicine is all that is needed for a fever. Dress your child lightly, and do not wrap him or her in blankets. Dressing lightly will help your child's body cool down.

Try these home treatment measures to make sure your child is drinking enough fluids and does not get dehydrated while he or she has a fever.

Newborns and babies younger than 1 year of age

Don't wait until you see signs of dehydration in your baby. These signs include your baby being thirstier than usual and having less urine than usual.

  • If you breast-feed your baby, nurse him or her more often. Offer each breast to your baby for 1 to 2 minutes every 10 minutes.
  • If you use a bottle to feed your baby, increase the number of feedings to make up for lost fluids. The amount of extra fluid your baby needs depends on your baby's age and size. For example, a newborn may need as little as 1 fl oz (30 mL) at each extra feeding, while a 12-month-old baby may need as much as 3 fl oz (90 mL) at each extra feeding.
  • Ask your doctor if you need to use an oral rehydration solution (ORS) if your baby still isn't getting enough fluids from formula or the breast. The amount of ORS your baby needs depends on your baby's age and size. You can give the ORS in a dropper, spoon, or bottle.
  • If your baby has started eating cereal, you may replace lost fluids with cereal. You also may feed your baby strained bananas and mashed potatoes if your child has had these foods before.

Children ages 1 through 11

  • Make sure your child is drinking often. Frequent, small amounts work best.
  • Allow your child to drink as much fluid as he or she wants. Encourage your child to drink extra fluids or suck on flavored ice pops, such as Popsicles. Note: Do not give your child fruit juice or soda pop. Fruit juice and soda pop contain too much sugar and not enough of the essential minerals (electrolytes) that are being lost. Diet soda pop lacks calories that your child needs.
  • Cereal mixed with milk or water may also be used to replace lost fluids.
  • If your child still is not getting enough fluids, you can try an oral rehydration solution (ORS).

Keep your child comfortable

Lowering your child's temperature is important when the fever is causing discomfort. If your child is uncomfortable:

Medicine you can buy without a prescription
Try a nonprescription medicine to help treat your child's fever or pain:
  • Acetaminophen, such as Tylenol
  • Ibuprofen, such as Motrin or Advil

Talk to your child's doctor before switching back and forth between doses of acetaminophen and ibuprofen. When you switch between two medicines, there is a chance your child will get too much medicine.

Safety tips
Be sure to follow these safety tips when you use a nonprescription medicine:
  • Carefully read and follow all labels on the medicine bottle and box.
  • Give, but do not exceed, the maximum recommended doses.
  • Do not give your child a medicine if he or she has had an allergic reaction to it in the past.
  • Do not give aspirin to anyone younger than age 20 unless directed to do so by your child's doctor.
  • Do not give naproxen (such as Aleve) to children younger than age 12 unless your child's doctor tells you to.
  • Try giving your child a sponge bath with lukewarm water. Do not use cold water, ice, or rubbing alcohol.
  • Encourage quiet activities.
  • Watch for signs of dehydration. These include your child being thirstier than usual and having darker urine than usual.

Symptoms to watch for during home treatment

Call your child's doctor if any of the following occur during home treatment:

  • Level of consciousness changes.
  • Your child has signs of dehydration and is not able to drink enough to replace lost fluids. Signs of dehydration include being thirstier than usual and having darker urine than usual.
  • Other symptoms develop, such as pain in one area of the body, shortness of breath, or urinary symptoms.
  • Symptoms become more severe or frequent.

The best way to prevent fevers is to reduce your child's exposure to infectious diseases. Hand-washing is the single most important prevention measure for people of all ages.

Childhood immunizations can reduce the risk for fever-related illnesses, such as Haemophilus influenzae type b (Hib) infection. Although no vaccine is 100% effective, most routine childhood immunizations are effective for 85% to 95% of the children who receive them. For more information, see the topic Immunizations.

To prepare for your appointment, see the topic Making the Most of Your Appointment.

You can help your child's doctor diagnose and treat your child's condition by providing the following information:

  • The history of the fever, including:
    • When did the fever start? Did it come on suddenly or increase over several hours?
    • Are you able to measure your child's temperature? How high is the fever?
    • Does the child have any other symptoms?
  • Does your child have frequent fevers?
    • How often does your child get a fever?
    • How long does the fever usually last?
  • Has your child had any other health problems during the past 3 months?
  • Has your child been eating, drinking, and playing normally?
  • Has anyone else in your family been ill?
  • Is your child in day care? If so, have any other children at the facility been ill?
  • Has your child recently traveled outside the country?
  • Has your child recently had close contact with immigrants or nonnative people?
  • Has your child had any animal or insect bites (including ticks) in the past 6 weeks?
  • Does your child have any health risks?
  • Abdominal Pain, Age 11 and Younger
  • Dehydration
  • Diarrhea, Age 11 and Younger
  • Ear Problems and Injuries, Age 11 and Younger
  • Heat-Related Illnesses
  • Nausea and Vomiting, Age 11 and Younger
  • Poisoning
  • Rash, Age 11 and Younger
  • Respiratory Problems, Age 11 and Younger

Other Works Consulted

  • Centigrade to Fahrenheit temperature conversions (2011). In MJ Hockenberry, D Wilson, eds., Wong's Nursing Care of Infants and Children, 9th ed., (inside back cover). St. Louis, MO: Mosby Elsevier.


By: Healthwise Staff Current as of: June 4, 2014
Medical Review: William H. Blahd, Jr., MD, FACEP - Emergency Medicine
H. Michael O'Connor, MD - Emergency Medicine

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