Everything you need to know

A fever is an abnormally elevated body temperature. It is often a sign of the body’s defense system working in overdrive to fight off an infection.

There are many different causes of fevers, and they can be associated with a number of symptoms depending on their causes.

Fever or elevated body temperature might be caused by:

• A virus

• A bacterial infection

• Heat exhaustion

• Certain inflammatory conditions such as rheumatoid arthritis — inflammation of the lining of your joints (synovium)

• A malignant tumor

• Some medications, such as antibiotics and drugs used to treat high blood pressure or seizures

• Some immunizations, such as the diphtheria, tetanus and acellular pertussis (DTaP) or pneumococcal vaccine

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How to measure body temperature in infants and children:

Infant:

The best and most effective way to measure a temperature is rectally. This is done by inserting a thermometer into the anus. If the temperature on the thermometer reads 38⁰C (100.4⁰F) or higher, that is considered a fever.

Children:

The most common is by mouth, or oral temperature. A reading above 37.8⁰C (100⁰F) or high is a fever. Other ways of measuring temperature include in the armpit (axillary temperature). A reading above 37.2⁰C (99⁰F) is a fever. Lastly, temperature measured by the ear (tympanic temperature) is a fever if it is 37.5⁰C (99.5⁰F) or higher.

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Complications:

Children between the ages of 6 months and 5 years may experience fever-induced convulsions (febrile seizures), which usually involve loss of consciousness and shaking of limbs on both sides of the body. Although alarming for parents, the vast majority of febrile seizures cause no lasting effects.

If a seizure occurs:

• Lay your child on his or her side or stomach on the floor or ground

• Remove any sharp objects that are near your child

• Loosen tight clothing

• Hold your child to prevent injury

• Don't place anything in your child's mouth or try to stop the seizure

Most seizures stop on their own. Take your child to the doctor as soon as possible after the seizure to determine the cause of the fever.

Call for emergency medical assistance if a seizure lasts longer than five minutes.

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Over-the-counter medications to treat fevers:

In the case of a high fever, or a low fever that's causing discomfort, your doctor may recommend an over-the-counter medication, such as acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin, others).

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Use these medications according to the label instructions or as recommended by your doctor. Be careful to avoid taking too much.

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High doses or long-term use of acetaminophen or ibuprofen may cause liver or kidney damage, and acute overdoses can be fatal. If your child's fever remains high after a dose, don't give more medication; call your doctor instead.

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Don't give aspirin to children, because it may trigger a rare, but potentially fatal, disorder known as Reye's syndrome.

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