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.
The average normal body temperature is about 37°C (98.6°F). It usually rises during the day from a low of 36.5°C (97.7°F) in the morning to a high of 37.5°C (99.5°F) in the late afternoon. Each child has a normal temperature range that may be different from another child's. Mild increases to 38°C (100.4°F) can be caused by exercising, wearing too many clothes, taking a hot bath, or being outside in hot weather.
Temperature varies depending on how you take it. The most common methods to measure it are:
To convert a temperature from one method to another, use the Interactive Tool: How Do Temperatures Compare?
You can also use:
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 40°C (104°F), 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 41°C (106°F). But outside heat-such as from being in a car that is parked in the sun-can cause body temperature to rise above 41.7°C (107°F), 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.
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:
Teething may cause a mild increase in your child's temperature. But if the temperature is higher than 38°C (100.4°F), look for symptoms that may be related to an infection or illness.
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.
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.
Health Tools help you make wise health decisions or take action to improve your health.
Many things can affect how your body responds to a symptom and what kind of care you may need. These include:
You have answered all the questions. Based on your answers, you may be able to take care of this problem at home.
Babies can quickly get dehydrated when they lose fluids because of problems like vomiting or fever.
Symptoms of dehydration can range from mild to severe. For example:
You can get dehydrated when you lose a lot of fluids because of problems like vomiting or fever.
Temperature varies a little depending on how you measure it. For children up to 11 years old, here are the ranges for high, moderate, and mild according to how you took the temperature.
Oral (by mouth), ear, or rectal temperature
A forehead (temporal) scanner is usually 0.3 C (0.5 F) to 0.6 C (1 F) lower than an oral temperature.
Armpit (axillary) temperature
Note: For children under 5 years old, rectal temperatures are the most accurate.
Certain health conditions and medicines weaken the immune system's ability to fight off infection and illness. Some examples in children are:
A baby that is extremely sick:
A baby that is sick (but not extremely sick):
Symptoms of difficulty breathing can range from mild to severe. For example:
Symptoms of difficulty breathing in a baby or young child can range from mild to severe. For example:
Sudden drooling and trouble swallowing can be signs of a serious problem called epiglottitis. This problem can happen at any age.
The epiglottis is a flap of tissue at the back of the throat that you can't see when you look in the mouth. When you swallow, it closes to keep food and fluids out of the tube (trachea) that leads to the lungs. If the epiglottis becomes inflamed or infected, it can swell and quickly block the airway. This makes it very hard to breathe.
The symptoms start suddenly. A person with epiglottitis is likely to seem very sick, have a fever, drool, and have trouble breathing, swallowing, and making sounds. In the case of a child, you may notice the child trying to sit up and lean forward with his or her jaw forward, because it's easier to breathe in this position.
If you're not sure if a child's fever is high, moderate, or mild, think about these issues:
With a high fever:
With a moderate fever:
With a mild fever:
Severe dehydration means:
Moderate dehydration means:
Mild dehydration means:
Severe dehydration means:
Moderate dehydration means:
Mild dehydration means:
You can use a small rubber bulb (called an aspirating bulb) to remove mucus from your baby's nose or mouth when a cold or allergies make it hard for the baby to eat, sleep, or breathe.
To use the bulb:
Don't do this more than 5 or 6 times a day. Doing it too often can make the congestion worse and can also cause the lining of the nose to swell or bleed.
Severe trouble breathing means:
Moderate trouble breathing means:
Mild trouble breathing means:
Symptoms of heatstroke may include:
Heatstroke occurs when the body can't control its own temperature and body temperature continues to rise.
Pain in children under 3 years
It can be hard to tell how much pain a baby or toddler is in.
Pain in children 3 years and older
Sudden tiny red or purple spots or sudden bruising may be early symptoms of a serious illness or bleeding problem. There are two types.
Petechiae (say "puh-TEE-kee-eye"):
Purpura (say "PURR-pyuh-ruh" or “PURR-puh-ruh”):
Symptoms of serious illness in a baby may include the following:
Symptoms of serious illness may include:
Shock is a life-threatening condition that may occur quickly after a sudden illness or injury.
Symptoms of shock in a child may include:
Fever can be a symptom of almost any type of infection. Symptoms of a more serious infection may include the following:
Many prescription and non-prescription medicines can trigger an allergic reaction and cause a fever. A few examples are:
Based on your answers, you may need care soon. The problem probably will not get better without medical care.
Based on your answers, you may need care right away. The problem is likely to get worse without medical care.
Based on your answers, you need emergency care.
or other emergency services now.
Based on your answers, the problem may not improve without medical care.
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.
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.
Lowering your child's temperature is important when the fever is causing discomfort. If your child is uncomfortable:
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.
Call your child's doctor if any of the following occur during home treatment:
The best way to prevent fevers is to reduce your child's exposure to infectious diseases. Handwashing is the single most important prevention measure for people of all ages.
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:
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.
ByHealthwise StaffPrimary Medical ReviewerWilliam H. Blahd, Jr., MD, FACEP - Emergency MedicineJohn Pope, MD - PediatricsAdam Husney, MD - Family MedicineKathleen Romito, MD - Family MedicineSpecialist Medical ReviewerDavid Messenger, MD
Current as ofMarch 20, 2017
Current as of: March 20, 2017
William H. Blahd, Jr., MD, FACEP - Emergency Medicine
& John Pope, MD - Pediatrics & Adam Husney, MD - Family Medicine & Kathleen Romito, MD - Family Medicine & David Messenger, MD
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