Encephalitis is swelling of the brain.

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Encephalitis can often be caused by an infection. Some common ones are:

It can also be caused by a problem with the immune system, such as a prior infection in the body or a tumor.

Risk Factors

Some things that may raise the risk of encephalitis are:

  • Spending time in an area where mosquito- or tick-borne viruses are common
  • Not getting vaccinated for diseases that can cause encephalitis
  • Having a weakened immune system


Symptoms may range from mild to severe. They may be:

  • Nausea and vomiting
  • Diarrhea
  • Belly pain
  • Fever
  • Headache
  • Sleepiness
  • Loss of feeling or numbness in the body
  • Stiff neck
  • Personality changes
  • Confusion
  • Seizures


The doctor will ask about your symptoms and health history. A physical exam will be done.

Blood tests will be done to look for signs of infection. A lumbar puncture may be done to test the fluid around spine.

Images may be taken of the brain to look for changes. This can be done with:


There are not many ways to treat viruses. They take time to leave the body. Most treatment will focus on supporting the body until the virus has passed.

These medicines may be given:

  • Antiviral drugs to shorten the length of the illness
  • Steroids to ease swelling in the brain
  • Diuretics to ease pressure in the head
  • Anti-seizure medicine to prevent and treat seizures


To lower your chances of getting encephalitis:

  • Make sure your vaccinations are up to date.
  • Protect yourself from mosquito and tick bites especially in high risk areas.

Revision Information

  • Reviewer: EBSCO Medical Review Board Rimas Lukas, MD
  • Review Date: 09/2019 -
  • Update Date: 10/18/2019 -