Viral Encephalitis

Side view of head and brain.

Encephalitis is inflammation of the brain. It may cause headache, stiff neck, irritability, fever, drowsiness, nausea and vomiting, confusion, bizarre behavior, or a seizure. It can be caused by infection from a virus, such as rabies, herpes, measles, mumps, chickenpox, West Nile virus, Zika virus, and others.

Encephalitis can be a complication of an infection with herpes, measles, mumps, chickenpox, or HIV. A virus that can cause encephalitis may be spread to a person by other people, animals, ticks, or insects (especially mosquitoes).

Antiviral medicines and other treatments may be used to treat viral encephalitis. In mild cases, most people recover fully in 2 to 4 weeks. However, in more severe cases, there are frequently long-term or permanent disabilities.


  • Stay current on vaccinations for common viral illnesses.

  • Drain areas of standing water where mosquitoes can breed.

  • Use insect repellent effective against mosquitoes and ticks, and wear protective clothing when in areas where mosquitoes and ticks are found.

  • Be cautious around stray cats and dogs, and wild animals.

  • Try not to have close contact with people who have viruses that can cause encephalopathy.

Home care

  • Rest in bed until you feel better. Stay home from school or work for at least one week to prevent spreading the virus to others.

  • Take any medicines as directed. Ask your healthcare provider about taking over-the-counter medicines (such as ibuprofen or acetaminophen) for fever and headache. (If you have chronic liver or kidney disease or ever had a stomach ulcer or gastrointestinal bleeding, let your healthcare provider know before using these medicines.)

  • If you have a fever, drink extra water, sports drinks or other fluids to prevent dehydration.

Follow-up care

Follow up with your healthcare provider during the next week or as directed by our staff. This helps ensure that you are getting better as expected.

When to seek medical advice

Call the healthcare provider if any of the following occur:

  • Fever of 100.4°F (38°C) or higher not better with medicine, or as directed by your healthcare provider

  • Headache or stiff neck continue or get worse

  • Not able to keep fluids down due to vomiting

Call 911

Call 911 or get emergency medical care if any of the following occur:

  • Increasing drowsiness, confusion, or bizarre behavior

  • Weakness of an arm or leg or one side of the face

  • Trouble with speech or vision

  • Trouble walking

  • Seizure or loss of consciousness

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