What causes fever?

Multiple types of infections, inflammatory disorders, and conditions can lead to a fever. More common infections include flu (influenza), pneumonia, appendicitis, and urinary tract infections. Rheumatoid arthritis and other connective tissue inflammatory conditions can also be present with a fever. Your baby may even have a fever when teething. Because there are so many possibilities, it is important to contact your doctor to address your concerns and answer your questions.

Possible causes of fever

Fever is a sign of many different types of infections:

  • Abscess
  • Appendicitis
  • Bronchitis
  • Cellulitis (bacterial skin infection)
  • Common cold (viral respiratory infection)
  • Ear infection
  • Gallbladder disease
  • Urinary tract infection

Other causes of fever

Fever can also be caused by inflammatory conditions including:

  • Arthritis
  • Autoimmune disorders
  • Cancer
  • Rheumatoid arthritis (chronic autoimmune disease characterized by joint inflammation)
  • Systemic lupus erythematosus (disorder in which the body attacks its own healthy cells and tissues)

Life-threatening causes of fever

In some cases, fever may be a symptom of a serious or life-threatening condition that should be immediately evaluated in an emergency setting. These conditions include:

  • Brain abscess
  • Epiglottitis (life-threatening inflammation and swelling of the epiglottis, a tissue flap between the tongue and windpipe)
  • Influenza, particularly in the very old or young
  • Liver abscess
  • Meningitis (infection or inflammation of the sac around the brain and spinal cord)
  • Pericarditis
  • Pneumonia
  • Septic shock
  • Tuberculosis (serious infection affecting the lungs and other organs)

Questions for diagnosing the cause of fever

To diagnose the underlying cause of fever, your doctor or licensed health care practitioner will ask you several questions related to your symptoms. Questions for diagnosing the cause of fever include:

  • When did the fever start?

  • How long have you had a fever?

  • Is the fever constant or intermittent?

  • Is the fever reduced by common over-the-counter medications, such as acetaminophen (Tylenol)?

  • Do you have any other symptoms, such as a cough or sore throat?

What are the potential complications of fever?

A rise in temperature is your body’s natural way of killing the infectious agent or preventing its spread. A fever is a sign of an infectious or inflammatory process, many of which can be treated without serious difficulties. In most cases, the complications are due to the underlying problem, not the fever itself. However, there are potential complications of untreated or poorly controlled fever, some of which can be serious and even life threatening including:

  • Brain damage from an extremely high fever
  • Dehydration due a decreased desire to drink fluids
  • Long term physical disability


  1. Fever. Medline Plus, a service of the National Library of Medicine National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/003090.htm.
  2. Fever. FamilyDoctor.org. http://familydoctor.org/online/famdocen/home/tools/symptom/503.html.
  3. Collins RD. Differential Diagnosis in Primary Care, 5th ed. Philadelphia: Lippincott, Williams & Williams, 2012.

What is fever?

Fever is an increase in your body’s temperature to a range that is above normal (98.6 degrees Fahrenheit). Normal body temperature can change throughout the day by a few degrees. Various factors can increase your body temperature including infection, eating, physical activity, medications, surrounding (room or outdoor) temperature, or a strong emotional response.

An oral te... Read more about fever informationintroduction


What other symptoms might occur with fever?

Fever may be accompanied by other symptoms, depending on the underlying disease, disorder or condition. Fever is usually a sign of infection, which often leads to a variety of symptoms. This section describes relatively common as well as more serious symptoms that may accompany a fever.

Symptoms may occur along with fever

Fever may occur with other common symptoms inclu... Read more about fever informationsymptoms

Medical Reviewer: William C. Lloyd III, MD, FACS Last Annual Review Date: Aug 9, 2013 Copyright: © Copyright 2014 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

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