Evaluation of fever of unknown origin in adults

  • Overview
  • Theory
  • Emergencies
  • Diagnosis
  • Resources
Last reviewed: 21 Sep 2025
Last updated: 31 Jul 2025

Summary

Differentials

Common

  • Tuberculosis (TB)
  • Abdominal or pelvic abscess
  • HIV
  • Rhinosinusitis, acute or chronic
  • Bacterial pneumonia
  • Urinary tract infection
Full details

Uncommon

  • Infective endocarditis
  • Dental abscesses
  • Osteomyelitis
  • Prostatitis, acute or chronic
  • Cytomegalovirus infection
  • Epstein-Barr virus infection
  • Coronavirus disease 2019 (COVID-19)
  • Rheumatic fever
  • Lyme disease
  • Chronic myeloid leukemia
  • Hodgkin lymphoma
  • Non-Hodgkin lymphoma
  • Metastatic carcinoma, primary unknown
  • Renal cancer
  • Myelodysplastic syndrome
  • Adult-onset Still disease
  • Polymyalgia rheumatica
  • Giant cell arteritis
  • Systemic lupus erythematosus
  • Crohn disease
  • Ulcerative colitis
  • Rheumatoid arthritis
  • Reactive arthritis
  • Drug-induced fever
  • Cirrhosis, complicated
  • Hepatitis
  • Deep vein thrombosis
  • Sarcoidosis
  • Periodic fever syndromes
  • Malaria
  • Typhoid fever
  • Rocky Mountain spotted fever
  • Ascariasis
  • Tularemia
  • Brucellosis
  • Psittacosis
  • Q fever
  • Pheochromocytoma
  • Hyperthyroidism
  • Munchausen syndrome
  • Dengue fever
Full details

Contributors

Authors

William F. Wright, DO, MPH

Assistant Professor

Division of Infectious Diseases, Department of Medicine

Johns Hopkins University School of Medicine

Baltimore

MD

Disclosures

WFW declares that he has no competing interests. WFW is an author of references cited in this topic.

Paul G. Auwaerter​,, MD

Professor

Division of Infectious Diseases, Department of Medicine

The Sherrilyn and Ken Fisher Center for Environmental Infectious Diseases

Johns Hopkins University School of Medicine

Baltimore

MD

Disclosures

PGA declares that he has no competing interests. PGA is an author of references cited in this topic.

Acknowledgements

Dr William F. Wright and Dr Paul G. Auwaerter would like to gratefully acknowledge Dr Roth and Dr Basello, previous contributors to this topic.

Peer reviewers

Kevin P. High, MD, MS, MACP, FIDSA

Professor of Medicine

Wake Forest University School of Medicine

Vice Chief Academic Officer, aLHS, Advocate Health

Winston-Salem

NC

Disclosures

KPH declares that he has no competing interests.

Peer reviewer acknowledgements

BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.

Disclosures

Peer reviewer affiliations and disclosures pertain to the time of the review.

References

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Key articles

Haidar G, Singh N. Fever of unknown origin. N Engl J Med. 2022 Feb 3;386(5):463-77. Abstract

Cunha BA, Lortholary O, Cunha CB. Fever of unknown origin: a clinical approach. Am J Med. 2015 Oct;128(10):1138.e1-1138.e15.Full text  Abstract

Wright WF, Auwaerter PG. Fever and fever of unknown origin: review, recent advances, and lingering dogma. Open Forum Infect Dis. 2020 May;7(5):ofaa132.Full text  Abstract

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

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