Fever of Unknown Origin (FUO)

Fever of Unknown Origin (FUO) is defined as a temperature of at 101° F that occurs for more than three weeks with no known cause. FUO can be caused by many factors and is a symptom of another disease or infection, including:

  • An unusual or rare infection
  • Cancer
  • Drug reactions
  • HIV infection
  • Inflammatory diseases
  • Viral infections

To diagnose FUO, your physician may order blood or urine tests, imaging (CT, MRI or x-ray scans), biopsies or endoscopies. FUO is treated through identification and treatment of the underlying condition.

Please consult your physician for more information regarding FUO and seek medical attention immediately if think you may be experiencing any symptoms of FUO.