Where to Take the Temperature

• Temperatures measured rectally are the most accurate. Temperatures measured orally, by electronic pacifier, by ear canal or temporal artery are also accurate if done properly. Temperatures measured in the armpit are the least accurate, but they are better than no measurement.
• Age less than 3 months old (90 days old):
  An armpit temperature is the safest and may be preferred for screening. If the armpit temperature is above 99° F (37.2° C), check it with a rectal temperature. The reason you need to take a rectal temperature for young infants is that if they have a true fever, they need to be evaluated immediately by a doctor.
• Age less than 4 or 5 years old:
  A rectal or electronic pacifier temperature are reliable. An ear or temporal artery thermometer can be used after 6 months old. An axillary (armpit) temperature is adequate for screening if it is taken correctly.
• Age older than 4 or 5 years old:
  Take the temperature orally (by mouth), by ear thermometer or by temporal artery thermometer.