Fever in Adults: Causes

Woman with fever holding thermometer

How does fever occur?

Fever occurs when the hypothalamus resets the normal temperature point to a higher level. Although the body is still working to balance the heat produced with the heat which it releases, since the set-point is now higher, the body temperature rises.

The increase in body temperature occurs for various reasons, such as release of certain chemicals called cytokines in response to invading microorganisms, cancer cells, or any other foreign matter. It is also in response to the body producing white blood cells and antibodies to protect it from the invading foreign matter.

Causes of fever

  • Any form of infection can cause the body to respond with a fever. These include viral and bacterial infections. Some examples are:

    Viral infections:

    • Common cold
    • Influenza
    • Meningitis
    • Dengue fever
    • Gastroenteritis

    Bacterial infections:

    • Dysentery
    • Bacterial pneumonia
    • Tuberculosis
    • Skin infections
    • Urinary tract infections
    • Otitis media (ear infections)
    • Eye infections
  • Although it is more common for a person to develop fever because of an infection, there are noninfectious causes of fever. These include:

    Autoimmune diseases

    • Systemic lupus erythematosus (SLE)
    • Rheumatoid arthritis


    • Leukemias
    • Lymphomas

    Drug induced

    • Sulfa drugs
    • Some antiepileptic medications
    • Antiretroviral medicines (for treatment of HIV)
    • Some antiarrhythmic medications (eg, amiodarone)

    Crystal-induced arthropathies

    • Gout (accumulation of uric acid in the joints)


    • Deep vein thrombosis

    Abdominal conditions

    • Acute pancreatitis

    Central nervous system conditions

    • Stroke (hemorrhagic and ischemic)

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