However, body temperature varies from person to person, usually between 36-37 C. Your own temperature will also fluctuate throughout the day as it is affected by factors such as sleep, exercise, eating and drinking; and for women, the stage of the menstrual cycle that has been reached.
What causes high temperature?
Most fevers are caused by pyrogens fever-inducing toxins released by viruses or bacteria. Pyrogens act on the temperature regulating centre in the brain. Common illnesses caused by such infection are the common cold, tonsillitis, influenza and urinary tract infections cystitis. Fever may also occur in non-infectious conditions such as dehydration, heart attack or cancer.
In addition you can develop a high fever from over-exposure to heat, and especially to the sun. This is known as heat stroke.
In children, a high temperature may be caused by infections such as measles or an upper respiratory tract infection such as tonsillitis.
For some children a high temperature can lead to convulsions or seizures which are caused by the effect that the fever has on the brain.
How is high temperature investigated and treated?
You can tell if you have a fever simply by taking your temperature with a thermometer. Placing one in the mouth will give you the most accurate reading.
To do this, put the bulb end of a clean thermometer under the tongue. Keep it there with the mouth closed for three minutes. On removal, check the temperature against the column of mercury.
Fever can be treated with antipyretic anti-fever drugs such as aspirin adults only, and paracetamol. These drugs also relieve any accompanying aches and pains.
The underlying cause may also be treated for example with antibiotics, if it is due to a bacterial infection.
What can I do myself?
You can take an aspirin or paracetamol which in most cases will reduce your fever. Children can be given paracetamol at the first sign of fever. Repeat the dose every four to six hours as needed.
Try to cool the body by stripping the person down and keeping them covered with a light cotton sheet, plus regular bathing in lukewarm water.
If heat stroke is causing the fever, move the sufferer to a cool shady place and remove as such clothing as possible. Place the person in a half sitting position and cover him or her with a wet sheet.
Be sure to keep the sheet wet. Maintain a cool flow of air, ideally with an electric fan, until the body temperature drops to 38 C. Then seek medical help immediately.
When should I see my doctor?
Do so if a fever lasts more than two days or if there are any other symptoms, such as severe headache with stiff neck, abdominal pain, or painful urination.
A very high fever is potentially dangerous as it can lead to coma in both adults and children. You should seek medical help immediately.
You should see the doctor if a fever occurs in a baby under six months old; in a child with a history of febrile convulsions seizures related to high temperatures; or in an elderly person.
A fever may be accompanied by:
Always see your doctor if your temperature remains above 38 C for longer than two days, or rinse obove 40 C. If you have taken aspirin or paracetamol and this does not reduce the fever, see a doctor as soon as possible.
In the case of babies, call your doctor if the temperature rises above 39 C, whatever the suspected cause. A high temperature can lead to seizures in some children.