A fever is usually a sign that something out of the ordinary is going on in your body. For an adult, a fever may be uncomfortable, but fever usually isn't dangerous unless it reaches 103 F (39.4 C) or higher. For very young children and infants, a slightly elevated temperature may indicate a serious infection.
But the degree of fever doesn't necessarily indicate the seriousness of the underlying condition. A minor illness may cause a high fever, and a more serious illness may cause a low fever.
Usually a fever goes away within a few days. A number of over-the-counter medications lower a fever, but sometimes it's better left untreated. Fever seems to play a key role in helping your body fight off a number of infections.
You have a fever when your temperature rises above its normal range. What's normal for you may be a little higher or lower than the average normal temperature of 98.6 F (37 C).
Depending on what's causing your fever, additional fever signs and symptoms may include:
High fevers between 103 F (39.4 C) and 106 F (41.1 C) may cause:
When to see a doctor
Taking a temperature
Although it's not the most accurate way to take a temperature, you can use an oral thermometer for an armpit (axillary) reading:
Use a rectal thermometer for infants:
Call your child's doctor if your child:
Ask your child's doctor for guidance in special circumstances, such as a child with immune system problems or with a pre-existing illness. Your child's doctor also may recommend precautions if your child has just started taking a new prescription medicine.
In addition, seek immediate medical attention if any of these signs or symptoms accompanies a fever:
Your normal 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 (36.1 C) to 99 F (37.2 C). Although most people consider 98.6 F (37 C) normal, your temperature may vary by a degree or more. Other factors, such as your menstrual cycle or heavy exercise, can affect your temperature.
A fever might be caused by:
Sometimes it's not possible to identify the cause of a fever. If you have a temperature of 101 F (38.3 C) or higher 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.
Complications of a fever may include:
If a seizure occurs:
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 10 minutes.
Preparing for your appointment
After you make an appointment with your family doctor, general practitioner or pediatrician, it's a good idea to be well prepared for your appointment. Here's some information to help you get ready for your appointment, and what to expect from the doctor.
What you can do
Preparing a list of questions ahead of time will help you make the most of your time together. List your questions from most important to least important. For fever, some basic questions to ask include:
In addition to the questions that you've prepared, don't hesitate to ask questions during your appointment anytime that you don't understand something.
What to expect from your doctor
Tests and diagnosis
Your doctor will look for an infection or noninfectious cause of your fever based on your other symptoms and a physical exam. You may need tests, such as blood tests, to confirm a diagnosis.
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.
Treatments and drugs
With low-grade fever, doctors don't always recommend trying to lower the body temperature. Doing so may prolong the illness or mask symptoms and make it harder to determine the cause.
Some experts believe that aggressively treating a fever interferes with the body's immune response. Viruses that cause colds and other respiratory infections thrive at normal body temperature. By producing a low-grade fever, your body may be helping to eliminate a virus.
Antibiotics don't treat viral infections, such as stomach infection (gastroenteritis) and mononucleosis. There are a few antiviral drugs used to treat some specific viral infections. However, the best treatment for most viruses is often rest and plenty of fluids.
Lifestyle and home remedies
You can try a number of things to make yourself or your child more comfortable during a fever:
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, after using the toilet, after spending time in a crowd or around someone who's sick, and after 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 moist towelettes or hand sanitizer with you for times when you don't have access to soap and water. When possible, teach your kids not to touch their noses, mouths or eyes — the main way viral infections are transmitted.
In addition, teach your children to turn away from others and to cover their mouths when coughing and their noses when sneezing.
Last Updated: 2011-06-01
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