What is a fever?

Fever is defined as a body temperature that is 1 or more degrees higher than normal. Normal body temperature varies from person to person, by age, by the time of day, and by the part of the body where it is measured. Other factors such as strenuous exercise, medicines, or even excitement can also affect body temperature.

Different types of thermometers are available to measure your temperature in different parts of your body. For example, there are thermometers that measure temperature in the mouth, ear, armpit, or rectum or on the forehead. Temperatures measured in the different areas may be different by one-half to 1 degree.

Fever can be a sign that the body is fighting an infection or that you have a medical problem, such as dehydration, a hormone disorder, certain cancers, an immune system problem, or a reaction to certain medicines that you are taking. Most often, the fever is associated with other symptoms of illness. Sometimes, the cause of the fever may not be known.

What can I expect in the hospital?

You may need to stay in the hospital because:

  • You have had a low-grade fever for 3 weeks or more without a known cause.
  • You have a high-grade fever without a known cause.
  • You have other chronic medical conditions that need careful observation and treatment.

Several things may be done while you are in the hospital to monitor, test, and treat your condition. They include:


  • You will be checked often by the hospital staff.
  • Your heart rate, blood pressure, and temperature will be checked regularly.
  • Your blood oxygen level may be monitored by a sensor that is attached to your finger or earlobe.


Testing may include:

  • Blood and urine tests to check for dehydration, infections, or other possible causes for your fever.
  • Blood, urine, or other tests to monitor how well your organs are functioning.
  • X-rays: Pictures of the inside of your chest to check for infection.
  • Computed tomography (CT) scan: A series of X-rays taken from different angles and arranged by a computer to show thin cross sections of the abdomen, pelvis, or other sites.


The treatment for fever depends on its cause, your symptoms, your overall health, and any complications you may have.

  • You will have a small tube (IV catheter) inserted into a vein in your hand or arm. This will allow medicine to be given directly into your blood and to give you fluids, if needed.
  • You may receive oxygen through a small tube placed under your nose or through a mask placed over your face.
  • Your provider may prescribe medicine to:
    • Reduce your fever
    • Treat or prevent an infection

What can I do to help?

  • You will need to tell your healthcare team if you have new or worsening:
    • Shortness of breath
    • Severe headache or a headache that does not go away with treatment
    • Severe pain when you straighten your neck or back
    • Vomiting
    • Sensitivity to bright lights
    • Abdominal pain
    • Back pain
    • Pain or burning with urination
    • Redness, swelling, tenderness, or other signs of infection on the skin
  • Ask questions about any medicine or treatment or information that you do not understand.

How long will I be in the hospital?

How long you stay in the hospital depends on many factors. The average amount of time to stay in the hospital with a fever is 2 to 3 days.

Developed by RelayHealth.
Acute Care Advisor 2015.1 published by RelayHealth.
Last modified: 2014-04-30
Last reviewed: 2014-04-14
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
Copyright ©1986-2015 McKesson Corporation and/or one of its subsidiaries. All rights reserved.

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