Differential Diagnosis for Fever with Headache

The following is a list of potential diagnoses for a patient presenting with fever and headache, categorized by likelihood and potential impact.

• Single Most Likely Diagnosis

  • Viral upper respiratory infection (e.g., common cold, influenza): This is often the most common cause of fever and headache in the general population, usually presenting with additional symptoms such as cough, sore throat, and runny nose.

• Other Likely Diagnoses

  • Sinusitis: An infection of the sinuses can cause fever, headache (often localized to the face), and nasal congestion.
  • Meningitis: Although less common, meningitis is a significant concern and presents with fever, headache, and stiff neck. It can be viral or bacterial.
  • Tension headache or migraine: While not infectious, these can be exacerbated by or mimic the symptoms of an infection, especially if accompanied by fever due to another cause.

• Do Not Miss Diagnoses

  • Bacterial meningitis: This is a medical emergency that requires prompt treatment. Symptoms can include fever, headache, stiff neck, and altered mental status.
  • Encephalitis: An inflammation of the brain, usually due to viral infections, which can present with fever, headache, confusion, and seizures.
  • Subarachnoid hemorrhage: A life-threatening condition that may present with sudden, severe headache (often described as "the worst headache of my life"), fever might not be a primary symptom but can occur.
  • Brain abscess: A rare but potentially deadly condition where an abscess forms in the brain, often presenting with fever, headache, and focal neurological deficits.

• Rare Diagnoses

  • Temporal arteritis (giant cell arteritis): More common in older adults, this condition involves inflammation of the blood vessels and can cause fever, headache, and visual disturbances.
  • Neurosyphilis: A complication of untreated syphilis that can cause a variety of neurological symptoms, including fever and headache.
  • Cerebral vasculitis: Inflammation of the blood vessels in the brain, which can cause fever, headache, and a range of neurological symptoms depending on the areas affected.
  • Rocky Mountain spotted fever or other tick-borne illnesses: These can present with fever, headache, and rash, and are more common in specific geographic areas.

Each of these diagnoses has a different set of risk factors, symptoms, and required treatments, emphasizing the importance of a thorough medical evaluation to determine the underlying cause of fever and headache.