What is a fever?

Fever refers to an elevation in body temperature. Technically, any body temperature above the normal oral measurement of 98.6 F (37 C) or the normal rectal temperature of 99 F (37.2 C) is considered to be elevated. However, these are averages, and your normal temperature may actually be 1 F (0.6 C) or more above or below the average of 98.6 F. Body temperature can also vary up to 1 F (0.6 C) throughout the day.

Thus, fever is not considered medically significant until body temperature is above 100.4 F (38 C). Fever serves as one of the body's natural defenses against bacteria and viruses which cannot live at a higher temperature. For that reason, low fevers should normally go untreated, unless accompanied by troubling symptoms.

Also, the body's defense mechanisms seem to work more efficiently at a higher temperature. Fever is just one part of an illness, many times no more important than the presence of other symptoms such as cough, sore throat, etc.

Fevers of 104 F (40 C) or higher demand immediate home treatment and subsequent medical attention, as they can result in delirium and convulsions, particularly in children.

How should I take a temperature for fever?

Digital thermometers can be used to measure rectal, oral, or axillary (under the armpit) temperatures. The American Academy of Pediatrics does not recommend use of mercury thermometers (glass), and they encourage parents to remove mercury thermometers from their households to prevent accidental exposure to this toxin.

Measuring an axillary (under the armpit) temperature for fever:

Axillary temperatures are not as accurate as rectal or oral measurements, and these generally measure one degree lower than a simultaneously obtained oral temperature.

• Place the tip of the digital thermometer in your child's armpit.



• Leave in place about one minute or until you hear a beep to check a digital reading.

Measuring fever by eardrum temperature:

Tympanic (ear) thermometers must be placed correctly in your child's ear to be accurate. Too much earwax can cause the reading to be incorrect.

Eardrum temperature measurements are not accurate in small children and should not be used in children under 3 years (36 months) of age. This is especially true in infants below 3 months of age when obtaining an accurate temperature is very important.

Measuring fever by oral temperature:

Children 4 to 5 years old and adults can have their temperature taken with a digital thermometer under the tongue with their mouth closed.

• Clean the thermometer with soapy water or rubbing alcohol and rinse.



• Turn the thermometer on and place the tip of the thermometer as far back under the tongue as possible.



• The thermometer should remain in place for about one minute or until you hear the beep. Check the digital reading.

Avoid hot or cold drinks within 15 minutes of oral temperature measurement to ensure correct readings.

Measuring fever by rectal temperature:

The American Academy of Pediatrics recommends rectal temperature measurements for children under 3 years, as this gives the most accurate reading of core temperature.

• Clean the thermometer with soapy water or rubbing alcohol and rinse with cool water.



• Use a small amount of lubricant, such as petroleum jelly, on the end.



• Place the child prone (belly-side down) on a firm surface, or place your child face up and bend his legs to his chest.



• After separating the buttocks, insert the thermometer approximately ½ to 1 inch into the rectum. Do not inset it too far.



• Hold the thermometer in place, loosely keeping your hand cupped around your child's bottom, and keep your fingers on the thermometer to avoid it accidently sliding further into the rectum. Keep it there for about one minute, until you hear the beep.



• Remove the thermometer, and check the digital reading.



• Label the rectal thermometer so it's not accidentally used in the mouth.

A rectal temperature will read approximately one degree higher than a simultaneously obtained oral temperature

How is fever treated?

Generally, if the fever does not cause discomfort, the fever itself need not be treated. It is not necessary to awaken an adult or child to treat a fever unless instructed to do so by your health-care practitioner.

The following medications may be used at home to treat a fever:

• Acetaminophen (Tylenol and others) can be used to lower a fever. The recommended pediatric dose can be suggested by the child's health-care provider. Adults without liver disease or other health problems can take 1000 mg (two "extra strength" tablets) every four to six hours or as directed by your physician.



• Ibuprofen (Motrin/Advil) can also be used for fever in patients over 6 months of age. Discuss the best dose with your doctor. For adults, 400-600 mg (two to three 200 mg tablets) can be used every six hours.



• Aspirin should not be used for fever in children or adolescents. Aspirin use in children and adolescents during a viral illness (especially chickenpox and influenza) has been associated with Reye syndrome. Reye syndrome is a dangerous illness which causes prolonged vomiting, confusion, and even coma and liver failure.

An individual with a fever should be kept comfortable and not overdressed. Overdressing can cause the temperature to rise further. Tepid water (85 F [30 C]) baths may help bring down a fever. Never immerse someone in ice water. This is a common misconception. Never sponge a child or an adult with alcohol; the alcohol fumes may be inhaled, causing many problems.

When should I seek medical care for a fever?

Any child below the age of 3 months who has a temperature of 100.4 F (38 C) should be seen by a physician or other health-care worker. If a child or adult has a history of cancer, AIDS, or other serious illness, such as heart disease or diabetes, medical care should be sought.

Otherwise, observe the person with the fever. If they appear sick or have symptoms that would suggest a major illness, such as meningitis (headache, stiff neck, confusion, problems staying awake), urinary tract infection (shaking chills, burning with urination), pneumonia (shortness of breath, cough), or any other signs of a serious illness, contact your health-care provider.

On the other hand, if the fever accompanies a simple cold, you can treat the fever as above and be assured that the fever is only a symptom of the illness. This is not to say that you should ignore a fever. If there are other associated symptoms that are bothersome, you should contact your health-care professional.

About 3% of all children between 18 months to 3 years of age will have a seizure (convulsion) with a high fever. Of those with a history of febrile seizure, approximately one-third will have another seizure associated with another febrile episode. Febrile seizures, while frightening to the parents, are not associated with long-term nervous-system side effects. Children used to be prescribed phenobarbital following a febrile seizure as a preventive measure (prophylaxis). This has been shown to be unbeneficial and possibly harmful, so it is not always recommended.

Aches, Pain, Fever At A Glance

• Although a fever could be considered any body temperature above the normal 98.6 F (37 C), medically, a person is not considered to have a significant fever until the temperature is above 100.4 F (38.0 C).
• Most fever is beneficial, causes no problems, and helps the body fight off infections. The main reason for treating a fever is to increase comfort.
• Children under 3 months old with a temperature of 100.4 F (38.0 C) or greater should be seen by a health-care provider. They may be quite ill and not show any signs or symptoms besides a fever. Infants less than 6 weeks old should be seen immediately by their doctor.
• Acetaminophen (Tylenol and others) and ibuprofen (Advil, Motrin) can be used to treat a fever. Aspirin should not be used in children or adolescents to control fever.

Previous contributing author and editor:

Author: Dennis S. Phillips, MD
Editor: Dennis Lee, MD

Medically reviewed by James Gerace, MD, Board Certified American Board of Internal Medicine with additional certification by the Subspecialty Board of Pulmonary Disease

References:

http://www.webmd.com/a-to-z-guides/body-temperature

http://www.aap.org/publiced/BR_Fever.htm

http://aappolicy.aappublications.org/cgi/content/full/pediatrics;103/6/e86

http://www.medscape.com/viewarticle/575603

Webster's New World Medical Dictionary, Third Edition

Related Posts Widget