Differential Diagnosis of Fever
Fever is most commonly caused by infection. (medlineplus.gov)
When no source is apparent, differential diagnoses are typically organized into infectious causes, malignancy, inflammatory/noninfectious disease, and miscellaneous causes. (aafp.org)
Infectious Causes
Respiratory tract infection
- Viral upper respiratory infection (common cold). (medlineplus.gov)
- Influenza or other influenza-like illness. (medlineplus.gov)
- Pharyngitis. (medlineplus.gov)
- Bronchitis. (medlineplus.gov)
- Pneumonia. (medlineplus.gov)
- Tuberculosis. (medlineplus.gov)
Gastrointestinal infection
- Viral gastroenteritis. (medlineplus.gov)
- Bacterial gastroenteritis. (medlineplus.gov)
Urinary infection
- Urinary tract infection. (merckmanuals.com)
Skin and soft tissue infection
- Cellulitis and other skin/soft-tissue infections. (medlineplus.gov)
Central nervous system infection
- Meningitis or encephalitis. (merckmanuals.com)
Systemic infection and bacteremia
- Bloodstream infection, including catheter-related bloodstream infection. (merckmanuals.com)
Other infectious sources
- Infective endocarditis. (aafp.org)
- Osteomyelitis and septic arthritis. (aafp.org)
- Hepatobiliary and intra-abdominal infection. (aafp.org)
Malignancy-Associated Fever
- Leukemia. (medlineplus.gov)
- Lymphoma. (medlineplus.gov)
- Solid tumors, including kidney cancer. (medlineplus.gov)
Inflammatory and Autoimmune Causes
- Connective tissue disease and autoimmune inflammatory syndromes. (aafp.org)
- Adult-onset Still disease. (aafp.org)
- Large-vessel vasculitis. (aafp.org)
- Temporal arteritis. (aafp.org)
- Polymyalgia rheumatica. (aafp.org)
Miscellaneous Noninfectious Causes
- Medication-related fever (drug fever). (merckmanuals.com)
- Transfusion reaction. (merckmanuals.com)
- Pressure sores. (merckmanuals.com)
- Venous thromboembolism, including deep vein thrombosis and pulmonary embolism. (merckmanuals.com)
- Atelectasis. (merckmanuals.com)
Special Clinical Contexts That Expand the Differential
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Fever with rash has a wide differential that includes infectious causes such as measles and varicella and noninfectious causes such as adult-onset Still disease and cutaneous drug reactions. (pmc.ncbi.nlm.nih.gov)
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Fever of unknown origin is defined clinically and after a minimum initial evaluation. (aafp.org)
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In adults with fever of unknown origin, the differential diagnosis is categorized as infection, malignancy, connective tissue diseases/granulomatous disease, and miscellaneous. (aafp.org)
Differential Diagnosis Framework for Practical Use
- Infection should be prioritized in the presence of focal infectious findings, exposure history, or immunocompromise. (medlineplus.gov)
- Malignancy should be considered with systemic symptoms, cytopenias, lymphadenopathy, or unexplained persistent fever. (aafp.org)
- Inflammatory/autoimmune disease should be considered when inflammatory symptoms are present or when infection has not been identified after initial workup. (aafp.org)
- Miscellaneous causes should be considered when there is a temporal association with medications, procedures, transfusion, immobility, or thromboembolism risk. (merckmanuals.com)