Fever

Summary

• Fever is when body temperature rises above normal (over 37°C).
• Fever has many possible causes e.g. infection, dehydration, allergic reaction.
• In adults, the level of temperature generally reflects the severity of the illness; in babies and young children, even a small change in temperature may be cause for concern.
• Seek medical help if a fever is accompanied by other signs e.g. pain, vomiting.

What is a fever?

Normal body temperature, when measured by an oral thermometer, is between 36.5°C and 37°C. Fever is when body temperature is over 37°C (37.8°C or more when measured rectally).

In an adult, the level of fever generally reflects the severity of the illness causing it. In a child, however, this is not necessarily the case. A child with a mild cold may have a temperature of 40°C, while a child with a serious illness - bacterial pneumonia, for example - may have a temperature lower than that.

In a newborn, the body's temperature control is not yet well developed. As a result, signs other than fever - poor appetite, lethargy, irritability - may be earlier indicators of an infection and are more helpful than temperature in assessing a newborn's condition.

What causes a fever?

A fever can be caused by a wide variety of factors. Dehydration, overexertion, mosquito bites, bee stings, allergic or toxic reactions and viral or bacterial infections are just a few. A fever of unknown origin is a condition defined as an elevated temperature lasting for three weeks or more without an identifiable cause.

Drugs to lower fever

Paracetamol (found in Tylenol, Panado and other over-the-counter medications) is a drug that helps lower fever. Paracetamol is also an analgesic (pain reliever), so it eases the discomfort and body aches that often accompany fever.

Note: in excessive amounts, this drug can cause liver damage. Be careful not to exceed the correct dosage.

Ibuprofen (Advil, Nuprin and others) is another fever-reducing medication that relieves mild to moderate aches and pains. Be sure to take the medication with food to prevent irritation of the stomach. Ibuprofen is available in liquid or pill form. Follow dosage directions on the product label. Don't give ibuprofen to infants younger than 6 months of age.

Do not give aspirin to a child or teenager with fever. Many fevers are caused by viral infections, and the combination of aspirin and viral illness has been linked to the development of Reye's syndrome, a very dangerous liver disease.

First aid for fever

• Administer paracetamol to reduce a fever of 40°C or higher. Do not use/give in higher doses or more frequently than directed.
• Encourage the person to drink plenty of water or fruit juices.
• For a temperature above 40°C, bathe or sponge the skin with lukewarm water (not cold water). You can fan the patient at the same time to improve the cooling effect of evaporation.
• Remove extra layers of clothing.
• Encourage the person to rest.

Call a doctor or go to the clinic or hospital if:

• A newborn has an elevated or lower than normal temperature (under 36.1 rectally)
• Any baby or child has a rectal temperature of 38 C or higher.
• An adult has a temperature of more than 39. ° C or has had a fever for more than three days.
• A child younger than two years has a fever for more than one day, or a child over age two has a fever for more than three days.
• A child has a fever after being left in a very hot car.

Seek immediate medical help if any of the following accompanies a fever:

• Severe headache
• Severe swelling of the throat
• Skin rash (especially purple color)
• Unusual sensitivity to bright light
• Stiff neck and pain when the head is bent forward
• Confusion or behavior out of the ordinary
• Persistent vomiting
• Difficulty breathing or chest pain
• Extreme listlessness or irritability
• Abdominal pain or pain when urinating
• A child is inconsolable or has difficulty waking
• Any signs of febrile seizure or convulsion in a child: loss of consciousness or responsiveness, muscle jerking, eye rolling, head jerks, hands and/or feet tap, absence attacks, loss of bowel and bladder control.

Last updated, July 2009.