What are the classic symptoms and treatment for encephalitis?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: June 4, 2025View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

From the Guidelines

Encephalitis is a medical emergency that typically presents with fever, headache, altered mental status, confusion, seizures, and neurological deficits, and prompt treatment with antiviral medications such as acyclovir is crucial to prevent permanent neurological damage or death. The classic symptoms of encephalitis include:

  • Fever
  • Headache
  • Altered mental status
  • Confusion
  • Seizures
  • Neurological deficits such as weakness, speech problems, or movement disorders
  • Neck stiffness
  • Light sensitivity
  • Coma in severe cases

Treatment depends on the cause, but generally includes antiviral medications, particularly acyclovir (10-15 mg/kg intravenously every 8 hours for 14-21 days) for suspected herpes simplex virus encephalitis, which should be started immediately while awaiting diagnostic confirmation 1. Supportive care is crucial and includes:

  • Managing seizures with anticonvulsants like levetiracetam (500-1500 mg twice daily)
  • Controlling fever with acetaminophen (650 mg every 4-6 hours)
  • Maintaining proper hydration
  • Monitoring for increased intracranial pressure Corticosteroids may be used in certain cases to reduce inflammation, particularly for autoimmune causes 1. The diagnostic evaluation of a patient who presents with encephalitis needs to be individualized and should be guided by epidemiologic and clinical clues and laboratory findings 1. Prompt treatment is essential as delays can lead to permanent neurological damage or death, and the brain inflammation in encephalitis disrupts normal neurological function, and while some patients recover completely, others may experience long-term complications requiring rehabilitation 1.

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

Classic Symptoms of Encephalitis

  • Fever 2, 3
  • Altered sensorium 2
  • Nausea and vomiting 2
  • Meningismus 2
  • Seizures 2, 3
  • Neurological deficits 2, 3
  • Coma in advanced stages 2
  • Headache 3
  • Confusion 3
  • Stiff neck 3
  • Hallucinations 3
  • Weakness 3

Treatment of Encephalitis

  • Antiviral medication, such as acyclovir, is the primary treatment for herpes simplex encephalitis 4, 5, 6
  • The recommended dose of acyclovir is 10 mg/kg/dose intravenous every 8 hours 6
  • The use of actual body weight or ideal body weight to calculate acyclovir dose in obese patients is unclear 6
  • Corticosteroids may be used as adjuvant therapy in some cases 4
  • Treatment should be initiated promptly to prevent delayed diagnosis and treatment, which can lead to significant morbidity and mortality 2

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.