Fever and Taking Your Child's Temperature
You've probably experienced waking in the middle of the night to find your child flushed, hot, and sweaty. Your little one's forehead feels warm. You immediately suspect a fever, but are unsure of what to do next. Should you get out the thermometer? Call the doctor?
In healthy kids, fevers usually don't indicate anything serious. Although it can be frightening when your child's temperature rises, fever itself causes no harm and can actually be a good thing — it's often the body's way of fighting infections. And not all fevers need to be treated. High fever, however, can make a child uncomfortable and worsen problems such as dehydration.
Here's more about fevers, how to measure and treat them, and when to call your doctor.
Fever happens when the body's internal "thermostat" raises the body temperature above its normal level. This thermostat is found in a part of the brain called the hypothalamus. The hypothalamus knows what temperature your body should be (usually around 98.6°F/37°C) and will send messages to your body to keep it that way.
Most people's body temperatures even change a little bit during the course of the day: It's usually a little lower in the morning and a little higher in the evening and can vary as kids run around, play, and exercise.
Sometimes, though, the hypothalamus will "reset" the body to a higher temperature in response to an infection, illness, or some other cause. Why? Researchers believe turning up the heat is the body's way of fighting the germs that cause infections and making the body a less comfortable place for them.
Causes of Fever
It's important to remember that fever by itself is not an illness — it's usually a symptom of an underlying problem.
Fevers have a few potential causes:
Infection: Most fevers are caused by infection or other illness. A fever helps the body fight infections by stimulating natural defense mechanisms.
Overdressing: Infants, especially newborns, may get fevers if they're overbundled or in a hot environment because they don't regulate their body temperature as well as older kids. However, because fevers in newborns can indicate a serious infection, even infants who are overdressed must be checked by a doctor if they have a fever.
Immunizations: Babies and kids sometimes get a low-grade fever after getting vaccinated.
Although teething may cause a slight rise in body temperature, it's probably not the cause if a child's temperature is higher than 100°F (37.8°C).
When Fever Is a Sign of Something Serious
In the past, doctors advised treating a fever on the basis of temperature alone. But now they recommend considering both the temperature and a child's overall condition.
Kids whose temperatures are lower than 102°F (38.9°C) often don't need medication unless they're uncomfortable. There's one important exception to this rule: If you have an infant 3 months or younger with a rectal temperature of 100.4°F (38°C) or higher, call your doctor or go to the emergency department immediately. Even a slight fever can be a sign of a potentially serious infection in very young infants.
If your child is between 3 months and 3 years old and has a fever of 102.2°F (39°C) or higher, call your doctor to see if he or she needs to see your child. For older kids, take behavior and activity level into account. Watching how your child behaves will give you a pretty good idea of whether a minor illness is the cause or if your child should be seen by a doctor.
The illness is probably not serious if your child:
And don't worry too much about a child with a fever who doesn't want to eat. This is very common with infections that cause fever. For kids who still drink and urinate (pee) normally, not eating as much as usual is OK.
Is it a Fever?
A gentle kiss on the forehead or a hand placed lightly on the skin is often enough to give you a hint that your child has a fever. However, this method of taking a temperature (called tactile temperature) doesn't give an accurate measurement.
Use a reliable thermometer to confirm a fever, which is when a child's temperature is at or above one of these levels:
But how high a fever is doesn't tell you much about how sick your child is. A simple cold or other viral infection can sometimes cause a rather high fever (in the 102°-104°F/38.9°-40°C range), but this doesn't usually indicate a serious problem. And serious infections might cause no fever or even an abnormally low body temperature, especially in infants.
Because fevers can rise and fall, a child might have chills as the body's temperature begins to rise. The child may sweat as the body releases extra heat as the temperature starts to drop.
Sometimes kids with a fever breathe faster than usual and may have a faster heart rate. You should call the doctor if your child is having trouble breathing, is breathing faster than normal, or continues to breathe fast after the fever comes down.
Types of Thermometers
Whatever thermometer you choose, be sure you know how to use it correctly to get an accurate reading. Keep and follow the manufacturer's recommendations for any thermometer.
Digital thermometers usually provide the quickest, most accurate readings. They come in many sizes and shapes and are available at most supermarkets and drugstores in a range of prices. Read the manufacturer's instructions to see what the thermometer is designed for and how it signals that the reading is complete.
Usually, digital thermometers can be used for these temperature-taking methods:
Turn on the thermometer and make sure the screen is clear of any old readings. Digital thermometers usually have a plastic, flexible probe with a temperature sensor at the tip and an easy-to-read digital display on the other end. If your thermometer uses disposable plastic sleeves or covers, put one on according to the manufacturer's instructions. Throw away the sleeve afterward and clean the thermometer according to the manufacturer's instructions before putting it back in its case.
Electronic ear thermometers measure the tympanic temperature (the temperature inside the ear canal). Although they're quick and easy to use in older babies and kids, they aren't as accurate as digital thermometers for infants 3 months or younger and are more expensive.
Plastic strip thermometers (small plastic strips that you press against the forehead) might tell you whether your child has a fever, but they don't give an exact measurement, especially in infants and very young children. If you need to know your child's exact temperature, plastic strip thermometers are not the way to go.
Forehead thermometers also can tell you if your child has a fever, but are not as accurate as oral or rectal digital thermometers.
Pacifier thermometers can be convenient, but their readings are less reliable than rectal temperatures and shouldn't be used in infants younger than 3 months. Kids also need to keep the pacifier in their mouth for several minutes without moving, which is a nearly impossible task for most babies and toddlers.
Glass mercury thermometers were once common, but should not be used because of possible exposure to mercury, an environmental toxin. (If you still have a mercury thermometer, do not simply throw it in the trash where the mercury can leak out. Talk to your doctor or your local health department about how and where to dispose of a mercury thermometer.)
Tips for Taking Temperatures
As any parent knows, taking a squirming child's temperature can be a challenge. But it's one of the most important tools doctors have to determine if a child has an illness or infection. The best method will depend on a child's age and temperament.
For kids younger than 3 months, you'll get the most reliable reading by using a digital thermometer to take a rectal temperature. Electronic ear thermometers aren't recommended for infants younger than 3 months because their ear canals are usually too small.
For kids between 3 months to 4 years old, you can use a digital thermometer to take a rectal temperature or an electronic ear thermometer to take the temperature inside the ear canal. You could also use a digital thermometer to take an axillary temperature, although this is a less accurate method.
For kids 4 years or older, you can usually use a digital thermometer to take an oral temperature if your child will cooperate. However, kids who have frequent coughs or are breathing through their mouths because of stuffy noses might not be able to keep their mouths closed long enough for an accurate oral reading. In these cases, you can use the tympanic method (with an electronic ear thermometer) or axillary method (with a digital thermometer).
To take a rectal temperature: Before becoming parents, most people cringe at the thought of taking a rectal temperature. But don't worry — it's a simple process:
To take an oral temperature: This process is easy in an older, cooperative child.
To take an axillary temperature: This is a convenient way to take a child's temperature. Although not as accurate as a rectal or oral temperature in a cooperative child, some parents prefer to take an axillary temperature, especially for kids who can't hold a thermometer in their mouths.
Whatever method you choose, keep these additional tips in mind:
Helping Kids Feel Better
Again, not all fevers need to be treated. And in most cases, a fever should be treated only if it's causing a child discomfort.
Here are ways to ease symptoms that often accompany a fever:
When to Call the Doctor
The exact temperature that should trigger a call to the doctor depends on the age of the child, the illness, and whether there are other symptoms with the fever.
Call your doctor if you have an:
Call the doctor if an older child has a fever of less than 102.2°F (39°C) but also:
Seek emergency care if your child shows any of these signs:
Also, ask your doctor for his or her specific guidelines on when to call about a fever.
Fever: A Common Part of Childhood
All kids get fevers, and in most cases they're completely back to normal within a few days. For older infants and kids (but not necessarily for infants younger than 3 months), the way they act is more important than the reading on your thermometer. Everyone gets cranky when they have a fever. This is normal and should be expected.
But if you're ever in doubt about what to do or what a fever might mean, or if your child is acting ill in a way that concerns you even if there's no fever, always call your doctor for advice.
Reviewed by: Yamini Durani, MD
Note: All information on KidsHealth® is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor.
© 1995- The Nemours Foundation. All rights reserved.