Differential Diagnosis for Fever and Headache
Single Most Likely Diagnosis
- Viral upper respiratory infection (e.g., common cold, influenza): This is the most common cause of fever and headache in the general population, often presenting with additional symptoms such as cough, sore throat, and runny nose.
Other Likely Diagnoses
- Sinusitis: An infection or inflammation of the sinuses can cause fever, headache (often localized to the face), and nasal congestion.
- Meningitis: Although less common, meningitis is a significant concern, especially in young adults and those with compromised immune systems, presenting with fever, headache, stiff neck, and potentially altered mental status.
- Tension headache: While not typically associated with fever, tension headaches can be exacerbated by viral infections and may present with a low-grade fever.
- Influenza: Similar to the common cold but often more severe, influenza can cause high fever, headache, and significant fatigue.
Do Not Miss Diagnoses
- Subarachnoid hemorrhage: A life-threatening condition that requires immediate medical attention, presenting with a sudden, severe headache (often described as "the worst headache of my life") and possibly fever if there's associated infection or inflammation.
- Encephalitis: An inflammation of the brain tissue, usually caused by viral infections, which can present with fever, headache, confusion, and altered mental status.
- Brain abscess: A rare but potentially deadly condition where an abscess forms in the brain, often presenting with fever, headache, and focal neurological deficits.
- Meningoencephalitis: An infection that affects both the meninges and the brain tissue, which can present with fever, headache, stiff neck, and altered mental status.
Rare Diagnoses
- Temporal arteritis: An inflammation of the blood vessels in the head, more common in older adults, which can cause fever, headache, and visual disturbances.
- Neurosyphilis: A complication of syphilis infection that can affect the central nervous system, presenting with a variety of symptoms including fever and headache.
- Cerebral malaria: A severe complication of malaria infection, which can cause fever, headache, and altered mental status, particularly in travelers to endemic areas.
- Histoplasmosis: A fungal infection that can cause fever, headache, and respiratory symptoms, more common in immunocompromised individuals or those exposed to contaminated soil.