All kids get a fever from time to time. A fever itself usually causes no harm and
can actually be a good thing — it's often a sign that the body is fighting an
infection.
But when your child wakes in the middle of the night flushed, hot, and sweaty,
it's easy to be unsure of what to do next. Should you get out the thermometer? Call
the doctor?
Here's more about fevers, including when to contact your doctor.
What Is a Fever?
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 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
that turning up the heat is a way for the body to fight the germs
that cause infections, making it a less comfortable place for them.
What Causes Fevers?
It's important to remember that fever by itself is not an illness — it's
usually a sign or symptom of another problem.
Fevers can be caused by a few things, including:
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. But 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 Is a Fever a Sign of Something Serious?
In healthy kids, not all fevers need to be treated. High fever, though, can make
a child uncomfortable and make problems (such as dehydration)
worse.
Doctors decide on whether to treat a fever by 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
medicine unless they're uncomfortable. There's one important exception: If
an infant 3 months or younger has 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 babies.
If your child is between 3 months and 3 years old and has a fever of 102.2°F
(39°C) or higher, call to see if your doctor 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:
- is still interested in playing
- is eating and drinking well
- is alert and smiling at you
- has a normal skin color
- looks well when his or her temperature comes down
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) won't give an accurate measurement.
Use a reliable digital thermometer to confirm a fever. It's a
fever when a child's temperature is at or above one of these levels:
- measured orally (in the mouth): 100°F (37.8°C)
- measured rectally (in the bottom): 100.4°F (38°C)
- measured in an axillary position (under the arm): 99°F (37.2°C)
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 mean there's a serious problem. In fact, a serious
infection, especially in infants, might cause no fever or even a low body temperature
(below 97°F or 36.1°C).
Because fevers can rise and fall, a child might have chills as the body's temperature
begins to rise. The child may sweat to release extra heat as the temperature starts
to drop.
Sometimes kids with a fever breathe faster than usual and may have a faster heart
rate. Call the doctor if your child has trouble breathing, is breathing faster than
normal, or is still breathing fast after the fever comes down.