First aid: Fever
Fever is a sign of a variety of medical conditions, including infection. Your normal temperature may differ slightly from the average body temperature of 98.6 F (37 C).
For young children and infants — especially newborns — even slightly elevated temperatures may indicate a serious illness. For adults, a fever usually isn't dangerous until it reaches 103 F (39.4 C) or higher.
For adults, don't treat fevers below 102 F (38.9 C) with any medications unless your doctor tells you to. If you have a fever of 102 F (38.9 C) or higher, your doctor may suggest taking an over-the-counter medication, such as acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin, others).
Adults also may use aspirin, but don't give aspirin to children or teenagers under the age of 19. It may trigger a rare, but potentially fatal, disorder known as Reye's syndrome. Also, don't give ibuprofen to infants younger than 6 months of age.
How to take a temperature
If you use a digital thermometer, be sure to read the instructions so that you know what the beeps mean and when to read the thermometer. Under normal circumstances, temperatures tend to be highest around 4 to 6 p.m. and lowest around 6 a.m.
Because of the potential for mercury exposure or ingestion, glass mercury thermometers have been phased out and are no longer recommended.
Rectally (for infants)
Taking a rectal temperature is also an option for older adults when taking an oral temperature is not possible.
A rectal temperature reading is generally 1 degree Fahrenheit (about 0.5 degree Celsius) higher than an oral reading.
Under the arm (axillary)
To take your child's axillary temperature, have the child sit in your lap, facing to the side. Place the thermometer under your child's near arm, which should be against your chest.
An axillary reading is generally 1 degree Fahrenheit (about 0.5 degree Celsius) lower than an oral reading.
When to seek medical help
When to seek emergency help
Last Updated: 2012-04-17
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