Fever
Original Article:
http://www.mayoclinic.com/invoke.cfm?id=DS00077
Overview
When you or your children aren’t feeling well, one of the first things you may do is check for a fever. Although a fever isn’t an illness itself, it’s usually a sign that something’s going on in your body. Yet fevers aren’t necessarily bad. In fact, they seem to play a key role in helping your body fight off a number of bacterial and viral infections.
A fever occurs when your temperature rises above its normal range. What’s normal for you may be a little higher or lower than the average temperature of 98.6 F. That’s why it’s hard to say just what a fever is. But a “significant” fever is usually defined as an oral or ear temperature of 102 F or a rectal temperature of 103 F. If you’re an adult, a fever may be uncomfortable, but it usually isn’t dangerous unless it rises above 103 F. For very young children and infants, however, even slightly elevated temperatures may indicate a serious infection. In newborns, a subnormal temperature — rather than a fever — may be a sign of serious illness.
Because a fever can occur with many different conditions, other signs and symptoms can often help identify the cause. For example, nausea and vomiting with a fever may mean gastroenteritis. A fever in addition to a cough that produces thick, yellow or green phlegm might be pneumonia.
If you don’t know why you have a fever, it’s best not to try to lower your temperature. This may only mask your symptoms and make it harder to determine the cause. In addition, some experts think that aggressively treating all fevers actually interferes with your body’s immune response. That’s because the viruses that cause colds and other respiratory infections thrive at cool temperatures. By producing a low-grade fever your body may actually be helping eliminate the virus. What’s more, most fevers go away in a relatively short time — usually within a few days.
Signs and symptoms
Depending on what’s causing your fever, your signs and symptoms may include:
Sweating
Shivering
Headache
Muscle aches
Lack of appetite
Dehydration
General weakness
Very high fevers, between 103 and 106 F, may cause hallucinations, confusion, irritability and even convulsions.
Approximately four percent of children under age 5 experience fever-induced seizures (febrile seizures). The signs of febrile seizures, which occur when a child’s temperature rises or falls rapidly, include a brief loss of consciousness and convulsions. Although these seizures can be extremely alarming, most children don’t experience any lasting effects. Febrile seizures are often triggered by a fever from a common childhood illness such as roseola, a viral infection that causes a high fever, swollen glands and a rash.
Causes
Even when you’re well, your body temperature varies throughout the day — it’s lower in the morning and higher in the late afternoon and evening. In fact, your normal temperature can range from about 97 F to 99 F. Although most people consider 98.6 F a healthy body temperature, yours may vary by a degree or more.
Your body temperature is set by your hypothalamus, an area at the base of your brain that acts as a thermostat for your whole system. When something’s wrong, your normal temperature is simply set a few points higher. The new set-point, for example, may be 102 F instead of 97 F or 98 F.
When a fever starts and your body tries to elevate its temperature, you feel chilly and may shiver to generate heat. At this point, you probably wrap yourself in your thickest blanket and turn up the heating pad. But eventually, as your body reaches its new set-point, you likely feel hot. And when your temperature finally begins to return to normal, you may sweat profusely, which is your body’s way of dissipating the excess heat.
A fever usually means your body is responding to a viral or bacterial infection. Sometimes heat exhaustion or an extreme sunburn or certain inflammatory conditions such as temporal arteritis — inflammation of an artery in your head — may cause fever as well. Some medications such as antibiotics and drugs used to treat hypertension or seizures may do the same. In rare instances, a malignant tumor or some forms of kidney cancer may cause a fever.
Viral infections, strep throat and ear infections (otitis media) are the most common causes of fevers in children. Some infants and children develop fevers after receiving routine immunizations, such as the diphtheria, tetanus and pertussis (DTaP) or pneumococcal vaccines.
Sometimes it’s not possible to identify the cause of a fever. If you have a temperature higher than 100.5 F for more than three weeks and your doctor isn’t able to find the cause after extensive evaluation, the diagnosis may be fever of unknown origin. In most cases, though, the reason for your fever can be found and treated.
When to seek medical advice
Fevers by themselves may not be a cause for alarm — or a reason to call a doctor. Yet there are some circumstances when you should seek medical advice for your baby, your child or yourself.
For infants
An unexplained fever is greater cause for concern in infants and children than in adults. Call your baby’s doctor if your baby:
Is younger than 3 months of age and has a rectal temperature of 100.5 F or more or an ear temperature of about 99.5 or higher. Even if your baby doesn’t have other signs or symptoms, call your doctor just to be safe.
Is more than 3 months of age and has a temperature of 102 F or higher.
Is a newborn who has a lower-than-normal temperature — under 95 F rectally.
Has a fever and unexplained irritability, such as marked crying when you change your baby’s diapers or when he or she is moved. Some infants might have a fever and seem lethargic and unresponsive. In infants and children under age 2, these may be signs of meningitis, an infection and inflammation of the membranes and fluid surrounding your brain and spinal cord. If you’re worried that your baby might have meningitis, see your doctor right away. Don’t wait until morning to see your usual physician — meningitis is an emergency.
For children
Children often tolerate fevers quite well, although high temperatures may cause parents a great deal of concern. Still, it’s best to be guided more by how your child acts than by any particular temperature. If your child has a fever but is responsive and is drinking plenty of fluids and wanting to play, there’s probably no cause for alarm.
Call your doctor if your child is listless or irritable, vomits, or has a severe headache or stomachache. But don’t treat low-grade fevers (generally an oral temperature between 99 and 101 F) with any medications unless advised by your doctor.
For adults
Call your doctor about a fever if:
Your temperature is more than 104 F
Your temperature has been higher than 101 F for more than three days
You have a temperature of 100.5 F for three weeks or more, but no other symptoms
In addition, call your doctor immediately if any of these signs and symptoms accompany a fever:
A severe headache
Severe swelling of your throat
Unusual skin rash
Unusual eye sensitivity to bright light
Significant stiff neck and pain when you bend your head forward
Mental confusion
Persistent vomiting
Difficulty breathing
Extreme listlessness or irritability
Abdominal pain or pain when urinating
Any other unexplained symptoms
Screening and diagnosis
Your doctor will likely diagnose the cause of your fever based on your other symptoms and a physical exam. Sometimes you may need additional tests to confirm a diagnosis. If your doctor suspects pneumonia, for instance, you may have a chest X-ray following your physical exam. In other cases you may have blood or urine tests to check for signs of infection.
If you have a low-grade fever that persists for three weeks or more, but have no other symptoms, your doctor may recommend a variety of tests to help find the cause. These may include blood tests and X-rays.
Complications
A rapid rise or fall in temperature may cause a febrile seizure in a small percentage of children younger than age 5. Although they’re 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. Remove any sharp objects that are near your child, loosen tight clothing and hold your child to prevent injury. Don’t place anything in your child’s mouth or try to stop the seizure. Although most seizures stop on their own, call for emergency medical assistance if the seizure lasts longer than five minutes.
If possible, try to time the seizure using your watch or a clock. Because they’re so alarming, seizures often seem to last longer than they really do. Also try to note which part of your child’s body begins to shake first. This can help your doctor understand the cause of the seizure. Your pediatrician should see your child as soon as possible.
Treatment
Medical treatment will depend on the cause of your fever. Your doctor will likely prescribe antibiotics for bacterial infections, such as pneumonia or tonsillitis. For viral infections, including stomach flu (gastroenteritis) and mononucleosis, the best treatment is often rest and plenty of fluids.
Your doctor may also suggest taking over-the-counter medications, such as acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin, others) to lower a very high fever. Adults may also use aspirin. But don’t give aspirin to children. It may trigger a rare, but potentially fatal, disorder known as Reye’s syndrome.
Prevention
The best way to prevent fevers is to reduce your exposure to infectious diseases. One of the most effective ways to do that is also one of the simplest — frequent hand washing.
Teach your children to wash their hands often, especially before they eat, and after using the bathroom, spending time in a crowded public place, or petting animals. Show them how to wash their hands vigorously, covering both the front and back of each hand with soap, and rinsing thoroughly under running water. Carry hand-washing towelettes with you for times when you don’t have access to soap and water. When possible, teach your kids not to touch their nose, mouth or eyes — the main way viral infections are transmitted.
Self-care
Because your body loses more water with a fever, be sure to drink plenty of fluids to avoid dehydration. Water is best, but if it’s hard to get your children to drink water, encourage them to drink juices or eat frozen ice pops. Adults and children should also get enough rest. Don’t be concerned with treating a fever just because it’s a fever. Often, a low-grade fever is actually helping fight off an infection. In addition, follow these guidelines for both children and adults:
For temperatures less than 102 F
Don’t give any medication for a fever in this range unless advised by your doctor. And don’t give children aspirin because of the risk of Reye’s syndrome. Instead, wear comfortable, light clothing and try bathing in lukewarm water. At bedtime, cover yourself or your children with just a sheet or light blanket.
For temperatures between 102 F and 104 F
Take acetaminophen or ibuprofen according to the label instructions or as recommended by your doctor. If you’re not sure about the proper dosage, be sure to check with your doctor or pharmacist. Adults may use aspirin instead. Be careful not to give too much medication. High doses or long-term use of acetaminophen may cause liver or kidney damage, and acute overdoses can be fatal. If you’re not able to get your child’s fever down, don’t give more medication. Call your doctor instead. Side effects of aspirin and other nonsteroidal anti-inflammatory drugs such as Motrin and Advil include stomach pain, bleeding and ulcers.
For temperatures greater than 104 F
Give adults or children acetaminophen or ibuprofen following the manufacturer’s instructions or as recommended by your doctor. Adults may use aspirin instead. If you’re not sure about the dosage, check with your doctor or pharmacist. Be careful not to give too much medication.
Acetaminophen is available in liquid, chewable and suppository forms for children, but it’s often easiest to give medications in liquid form. For a small child, use a syringe with measurements on the side and a bulb on the tip. Gently squirt the medicine in the back corners of your child’s mouth.
Use a sponge bath of lukewarm water to try to bring your own or your child’s temperature down. Recheck the temperature every 30 minutes. When it’s less than 102 F, you can stop sponging. If your child shivers in the bath, stop the bath, dry your child and wait. Shivering actually raises the body’s internal temperature — shaking muscles generates heat. If the fever doesn’t moderate or your child has a febrile seizure that lasts longer than five minutes, seek immediate medical care.
Taking a temperature
To check your or your child’s temperature level, you can choose from several types of thermometers, including electronic thermometers and ear (tympanic) thermometers. Thermometers with digital readouts and those that take the temperature quickly from the ear canal are especially useful for young children and older adults. Because glass mercury thermometers harm both humans and the environment, they’re being phased out and are no longer recommended.
Although it’s not the most accurate way to take a temperature, you can also use an oral thermometer for an armpit (axillary) reading. Place the thermometer in the armpit with arms crossed across the chest. Wait five minutes. The axillary temperature is about one degree less than an oral or rectal temperature.
Use a rectal thermometer for infants. Place a dab of petroleum jelly on the bulb. Lay your baby on his or her tummy. Carefully insert the bulb one-half inch to 1 inch into your baby’s rectum. Hold the bulb and your baby still for three minutes. Don’t let go of the thermometer while it’s inside your baby. If your baby squirms, it could go deeper and cause an injury.
By Mayo Clinic staff
DS00077
September 12, 2003
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