Fever grades in adults
In an adult, a fever may be elevated, high or very high:
An elevated body temperature is between 37.5°C and 38°C (99.5°F to 100.4°F).
A fever is 38°C to 39.5°C (100.4°F to 103.1°F).
A high fever is 39.5°C (103.1°F).
A very high fever is above 41°C (105.8°F ).
Fever in babies and children
According to the American Academy of Pediatrics (AAP), normal temperature in children varies with a child’s age, time of day and level of activity.
Fever is defined as a temperature of 38°C (100.4°F).
A fever that requires a call to the pediatrician right away would be 38°C (100.4°F) or higher for a baby under 3 months old.
A fever above 40°C (104°F) requires a call to the doctor at any age.
How to measure fever
To take your temperature, a digital thermometer is recommended instead of a mercury thermometer, especially in children, because mercury from a broken thermometer may be toxic. There are three types of digital thermometers. There are many variations, so it is important to read and follow the thermometer instructions carefully. They all must be turned on and they will beep to tell you when to read them:
A digital multi-use thermometer can be used to take a rectal, oral (mouth) or axillary (armpit) temperature in adults and children. In general, oral and armpit temperatures have not shown to be as accurate as rectal. Oral use is not recommended for children under age 4, according to the AAP, and AAP notes that rectal use is best, especially for infants and children under 3 months. Always clean the thermometer before and after use, and do not use a thermometer orally that has been used rectally. Do not take an oral temperature for 30 minutes after a hot or cold drink.
A temporal or forehead artery thermometer reads your temperature from a blood vessel under the skin of your temple or forehead. You will need to check the instructions to find out how far away from your skin to hold it. If you have been in hot or cold temperatures, you should adjust to normal temperature before taking a reading.
A tympanic digital thermometer measures heat inside your ear canal. This type can be used for anyone except babies.
