Topic Overview
Fever is the body's normal and healthy
reaction to infection and other illnesses, both minor and serious. It helps the
body fight infection. Fever is a symptom, not a disease. In most cases, having
a fever means you have a minor illness. When you have a fever, your other
symptoms will help you determine how serious your illness is.
Temperatures in this topic are oral temperatures. Oral
temperatures are usually taken in older children and adults.
Normal body temperature
Most people have an average
body temperature of about
98.6°F (37°C), measured orally
(a thermometer is placed under the tongue). Your temperature may be as low as
97.4°F (36.3°C) in the morning
or as high as 99.6°F (37.6°C)
in the late afternoon. Your temperature may go up when you exercise, wear too
many clothes, take a hot bath, or are exposed to hot weather.
Fever temperatures
A fever is a high body
temperature. A temperature of up to
102°F (38.9°C) can be helpful
because it helps the body fight infection. Most healthy children and adults can
tolerate a fever as high as
103°F (39.4°C) to
104°F (40°C) for short periods
of time without problems. Children tend to have higher fevers than
adults.
The degree of fever may not indicate how serious the
illness is. With a minor illness, such as a cold, you may have a temperature,
while a very serious infection may cause little or no fever. It is important to
look for and evaluate other symptoms along with the fever.
If you
are not able to measure your temperature with a thermometer, it is important to
look for other symptoms of illness. A fever without other symptoms that lasts 3
to 4 days, comes and goes, and gradually reduces over time is usually not a
cause for concern. When you have a fever, you may feel tired, lack energy, and
may not eat as much as usual. High fevers are not comfortable, but they rarely
cause serious problems.
Oral temperature taken after smoking or
drinking a hot fluid may give you a false high temperature reading. After
drinking or eating cold foods or fluids, an oral temperature may be falsely
low. For information on how to take an
accurate temperature, see the topic
Body Temperature.
Causes of fever
Viral infections, such as colds and
flu, and
bacterial infections, such as a
urinary tract infection or
pneumonia, often cause a fever.
Travel
outside your native country can expose you to other diseases. Fevers that begin
after traveling in other countries need to be evaluated by your health
professional.
Fever and respiratory symptoms are difficult to
evaluate during the flu season. A fever of
102°F (38.9°C) or higher for 3
to 4 days is common with the flu. For more information, see the topic
Respiratory Problems, Age 12 and Older.
Recurrent fevers are those that occur 3 or more times within 6 months and
are at least 7 days apart. 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
fever is recurring. If you have frequent or recurrent fevers, it may be a
symptom of a more serious problem. Talk to your doctor about your
fevers.
Treating a fever
In most cases, the illness that
caused the fever will clear up in a few days. You usually can treat the fever
at home if you are in good health and do not have any medical problems or
significant symptoms with the fever. Make sure that you are taking enough foods
and fluids and urinating in normal amounts.
Use the Check Your Symptoms section to decide if and when
you should see a doctor.
Home Treatment
It is easy to become dehydrated
when you have a
fever. Watch for
early signs of dehydration and
drink extra fluids, especially water. Adults should
drink at least 10 glasses of liquid a day to replenish lost fluids. Children
between the ages of 4 and 10 should drink at least 6 to 10 glasses. You may
feel better if you eat light, easily digested foods, such as soup.
Many people find that taking a lukewarm [80°F (27°C) to
90°F (32°C)]
shower or bath makes
them feel better when they have a fever. Do not try to take a shower if you are
dizzy or unsteady on your feet. Increase the water temperature if you start to
shiver. Shivering is a sign that your body is trying to raise its temperature.
Do not use rubbing alcohol, ice, or cold water to cool
your body.
Dress lightly when you have a fever. This will help
your body cool down. Wear light pajamas or a light undershirt. Do not wear very
warm clothing or use heavy bed covers. Keep room temperature at
70°F (21°C)
or lower.
If you are unable to measure your temperature, you
need to look for other symptoms of illness every hour while you have a fever
and follow home treatment measures.
Medicine you can buy without a prescription| Try a nonprescription
medicine to help treat your fever or pain: |
|---|
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 directions
on the medicine bottle and box.
- Do not take more than the
recommended dose.
- Do not take a medicine if you have had an
allergic reaction to it in the past.
- If
you have been told to avoid a medicine, call your doctor before you take
it.
- If you are or could be pregnant, do not take any medicine other
than acetaminophen unless your doctor has told you to.
- Do not give aspirin to anyone younger than age 20 unless your doctor tells you to.
- Do
not give your child naproxen sodium (such as Aleve) to children younger than
age 12 unless your child's doctor tells you to.
|
Be sure to check your temperature every 2 to 4 hours to make
sure home treatment is working.
Symptoms to Watch For During Home Treatment
Use the Check Your Symptoms section to
evaluate your symptoms if any of the following occur during home
treatment:
- Level of consciousness
changes.
- You have
signs of dehydration and you are unable to drink
enough to replace lost fluids.
- Fever lasts longer than 4
days.
- Other symptoms develop, such as pain in one area of the body,
a cough, or urinary symptoms.
- Fever recurs more than once over 3
weeks.
- Symptoms become more severe or frequent.