- Take the Cold & Flu Quiz
- Do Flu Shots Cause Flu?
- Is It a Cold or The Flu?
- Patient Comments: Fever - Treatments
- Patient Comments: Fever - Signs and Symptoms
- Patient Comments: Fever - Complications
- Find a local Family Physician in your town
- Fever facts
- What is a fever?
- What causes a fever?
- What are the signs and symptoms of a fever?
- How do health-care professionals diagnose a fever?
- How should someone take a temperature for fever?
- What is the treatment for a fever?
- What are home remedies for a fever?
- When should someone seek medical care for a fever?
- What kind of doctors treat a fever?
- What are complications of a fever?
- What is the prognosis for a fever?
- Is it possible to prevent a fever?
- Where can people find more information about fevers?
Quick GuideSore Throat or Strep Throat? How to Tell the Difference
How do health-care professionals diagnose a fever?
Along with having generalized symptoms of a fever, taking one's temperature with a thermometer can confirm the diagnosis of a fever. A temperature greater than 100.4 F in adults or children is considered a fever.
Different tests may be done by a doctor, such a blood and imaging tests, to determine the cause of a fever and if the cause of the fever needs to be treated.
How should someone take a temperature for fever?
Digital thermometers can be used to measure rectal, oral, or axillary (under the armpit) temperatures. The American Academy of Pediatrics does not recommend use of mercury thermometers (glass), and they encourage parents to remove mercury thermometers from their households to prevent accidental exposure to this toxin.
Measuring an axillary (under the armpit) temperature for fever
Axillary temperatures are not as accurate as rectal or oral measurements, and these generally measure 1 degree lower than a simultaneously obtained oral temperature.
- Place the tip of the digital thermometer in a child's armpit.
- Leave the thermometer in place about one minute or until one hears a beep to check a digital reading.
Measuring fever by eardrum temperature
Tympanic (ear) thermometers must be placed correctly in a child's ear to be accurate. Too much earwax can cause the reading to be incorrect.
Eardrum temperature measurements are not accurate in small children and should not be used in children under 3 years (36 months) of age. This is especially true in infants below 3 months of age when obtaining an accurate temperature is very important.
Measuring fever by oral temperature
People 4 years old and older can have their temperature taken with a digital thermometer under the tongue with their mouth closed.
- Clean the thermometer with soapy water or rubbing alcohol and rinse.
- Turn the thermometer on and place the tip of the thermometer as far back under the tongue as possible.
- The mouth should remain closed, as an open mouth can cause readings to be inaccurate.
- The thermometer should remain in place for about one minute or until one hears the beep. Check the digital reading.
Avoid hot or cold drinks within 15 minutes of oral temperature measurement to ensure correct readings.
Measuring fever by rectal temperature
The American Academy of Pediatrics recommends rectal temperature measurements for children and toddlers under 3 years of age, as this gives the most accurate reading of core temperature.
- Clean the thermometer with soapy water or rubbing alcohol and rinse with cool water.
- Use a small amount of lubricant, such as petroleum jelly, on the end.
- Place the child or baby prone (belly-side down) on a firm surface, or place a child face up and bend his legs to his chest.
- After separating the buttocks, insert the thermometer approximately ½ to 1 inch into the rectum. Do not insert it too far.
- Hold the thermometer in place, loosely keeping one's hand cupped around the child's bottom, and keep one's fingers on the thermometer to avoid it accidently sliding further into the rectum. Keep it there for about one minute, until one hears the beep.
- Remove the thermometer, and check the digital reading.
- Label the rectal thermometer so it's not accidentally used in the mouth.
A rectal temperature will read approximately 1 degree higher than a simultaneously obtained oral temperature.