Normal body temperature

Is there a normal body temperature?

Most people think of 'normal' body temperature as 37C (98.6F), measured using a thermometer in the mouth.

However, the concept of there being a normal body temperature is somewhat misleading. In fact normal body temperature can vary according to a wide range of factors including a person's age, the time of day and whether someone is active or not.

The 'normal' benchmark for body temperature was established by a 19th century German physician called Dr Carl Wunderlich. He is credited with taking temperature readings from thousands of patients, which led him to propose that 37C was normal body temperature.

So, what is normal body temperature?

Some studies have disputed Dr Wunderlich's findings. For instance, a 1992 evaluation of his work in the US, and based on 148 participants, found that 36.8C was a more accurate figure.

Normal body temperature also depends on where the temperature reading is taken. For instance, a reading from the armpit will be about 0.5C lower than the body's core temperature.

Research from Winthrop University in the US published in 2006 found that older people have lower temperatures and that, even when ill, their bodies may never reach temperatures that would be regarded as fever.

The NHS says that a normal temperature is around 37C (98.6F), although it depends on:

• The person
• Their age
• What they've been doing
• The time of day
• Which part of the body you take the temperature from

It is generally accepted that normal body temperature ranges between 36.1C (97F) to 37.2C (99F).