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
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
Can a high body temperature be dangerous?
Heatstroke occurs when the body fails to regulate its own temperature and body
temperature continues to rise. Symptoms of heatstroke include mental changes
(such as confusion, delirium, or unconsciousness) and skin that is red, hot,
and dry, even under the armpits.
Classic heatstroke can develop
without exertion when a person is exposed to a hot environment and the body is
unable to cool itself effectively. In this type of heatstroke, the body's
ability to sweat and transfer the heat to the environment is reduced. A person
with heatstroke may stop sweating. Classic heatstroke may develop over several
days. Babies, older adults, and people who have chronic health problems have the
greatest risk of this type of heatstroke.
may develop when a person is working or exercising in a hot environment. A
person with heatstroke from exertion may sweat profusely, but the body still
produces more heat than it can lose. This causes the body's temperature to rise
to high levels.
Both types of heatstroke cause severe dehydration
and can cause body organs to stop functioning. Heatstroke is a life-threatening medical emergency requiring emergency medical
Why It Is Done
Body temperature is checked to:
- Detect fever.
- Detect abnormally low
body temperature (hypothermia) in people who have been exposed to
- Detect abnormally high body temperature (hyperthermia) in
people who have been exposed to heat.
- Help monitor the
effectiveness of a fever-reducing medicine.
- Help plan for pregnancy
by determining if a woman is ovulating.
How To Prepare
Take your temperature several times
when you are feeling well to find out what is normal for you. Check your
temperature in both the morning and evening, since body temperature can vary by
as much as 1°F (0.6°C) throughout the day.
Wait at least 20 to 30
minutes after smoking, eating, or drinking a hot or cold liquid before taking
your temperature. Also, wait at least an hour after vigorous exercise or a hot
Several different types of thermometers are
- Electronic thermometers
are plastic and shaped like a pencil, with a display window at one end and the
temperature probe at the other end. They work by measuring how well electricity
travels through a wire. Electronic thermometers are used in the mouth, rectum,
or armpit. They are easy to use and easy to read. If you buy an
electronic thermometer, check the package for information about its accuracy.
See a picture of an
electronic thermometer .
- Ear thermometers are plastic and come in
different shapes. They use infrared energy to measure body temperature. The
small cone-shaped end of the thermometer is placed in the ear, and body
temperature is shown on a digital display. The results appear within seconds. Some
models also show the corresponding oral and rectal readings. See a picture of
an ear thermometer .
- Temporal artery thermometers are electronic devices that measure body temperature on the skin over an artery in the forehead (superficial temporal artery). The device has a small "cup" that is moved across the skin over the artery. Infrared energy is used to determine the temperature. When used correctly, temporal artery thermometers are accurate for measuring body temperature.1, 2
- Disposable thermometers are thin flat pieces of plastic with colored dots and
temperature markings on one end. The color of the dots shows the temperature.
Disposable thermometers can be used in the mouth or rectum. A patch form can be
used on a baby's skin to measure temperature continuously for 48 hours. These
thermometers are safe, but they are not as accurate as electronic or ear thermometers. They do not contain
glass, latex, or mercury. You can reuse the thermometer during an illness and
then throw it away.
- Forehead thermometers use skin
temperature to determine body temperature. They are thin pieces of plastic with numbers on them. You press the
strip against a person's forehead, and the temperature makes some numbers
change colors or light up. These thermometers are not very accurate.
- Pacifier thermometers are shaped like a baby's
pacifier but have a display that shows the temperature. You place the pacifier
in your child's mouth to measure temperature. These thermometers may take
longer to get a reading and are not as accurate as other types.
Glass thermometers containing mercury are no longer
recommended. If you have a glass thermometer, contact your local health
department for instructions on how to dispose of it safely. If you break a
glass thermometer, call your local poison control center immediately.