Understanding Body Temperature


What Is Normal Body Temperature


body temperature

Body temperature is directly related to your body’s ability to increase or decrease heat, maintaining your temperature at a safe level.


When Your Body Needs To Cool Itself Down

  • Blood vessels in your skin expand allowing the blood to move towards the skins surface to be cooled.
  • The body’s most efficient cooling system is evaporation. When you sweat it evaporates off the surface of your skin cooling you as it does so.


When Your Body Needs To Warm Itself Up

  • Blood vessels in your skin contract reducing blood flow to the skins surface to save body heat.
  • You may begin to shiver. The muscular contractions responsible for causing you to shiver also generate heat increasing your temperature.


Normal Body Temperature Vs Abnormal Body Temperature


normal body temperature


  • A temperature reading from the ear, or rectally, will be higher than an oral reading
  • A temperature reading from the armpit will be lower than an oral reading
  • The most accurate way to take a temperature is rectally


Normal Temperature

  • 37°C (98.6°F) is considered the normal average body temperature, but this can vary by around 0.6°C or (1°F) in some people.
  • Your temperature will change during the day, usually being at its lowest in the mornings, and exercising on a hot day may cause your temperature to rise by as much as 0.6°C or (1°F).
  • The body temperature of a woman may change around 0.6°C or (1°F) during her menstrual cycle and this will peak during ovulation.


Abnormal Temperature

Oral, Ears or Rectal Readings

Fever:  38°C (100.4°F) to 39.9°C (103.9°F)

High Fever: 40°C (104°F) or higher


Armpit Measurements

Fever: 37.4°C (99.4°F) to 39.4°C (102.9°F)

High Fever: 39.5°C (103°F) or higher



  • An Ear Temperature or rectal temperature which is less than 36.1°C (97°F) is considered low body temperature (hypothermia)
  • An Ear Temperature or rectal temperature which is higher than 40°C (104°F) is a sign of heat stroke


Taking a Temperature

  • Take your temperature when you are well to find out what is normal for you
  • If you eat or drink something hot or have a smoke wait 20 to 30 minutes before taking your temperature
  • If you have a hot bath or exercise wait at least an hour
  • Read and follow the directions on your thermometer carefully


The Best Thermometers


Electronic thermometers

electronic thermometer 

  • Pencil shaped, made of plastic.
  • Have a temperature probe at one end with a display window at the other end
  • Used in the armpit, mouth or rectum.

Ear thermometers

ear thermometer

  • Made of plastic and come in different shapes and sizes
  • Have a small cone shaped end which gets inserted into the ear
  • Have a digital display and show the temperature in seconds


Disposable thermometers

disposable-dot thermometers

  • Made of plastic and have colored dot temperature markings on one end
  • Can be used in the mouth or inserted into the rectum
  • Come in a patch form which can be placed on a babies skin to continuously monitor the body temperature
  • Are less accurate than electronic or ear thermometers


Pacifier Thermometers

pacifier thermometer

  • Shaped like a babies pacifier with a temperature display on one end, these are used in the mouth only
  • May take longer than other thermometers to get a reading
  • Not as accurate as other thermometers


The old glass thermometers which contain mercury should be disposed of immediately. Call your local Department Of Health to find out the safe disposal methods.

If you break a thermometer containing mercury call the poisons information centre in your area and follow cleanup directions.


When using a thermometer read the instructions carefully and follow them to the letter. Although taking a temperature is a very safe and simple process you may cause injury if you are not careful. This is more of a concern with the ear and rectal thermometers.