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If you or your child has symptoms of encephalitis, a seizure or any change in level of alertness, go to the emergency department straight away.

Key facts

  • Encephalitis is inflammation of your brain, which can be life-threatening.
  • It is most commonly caused by a virus.
  • Encephalitis can cause drowsiness, confusion, seizures, fever and headache.
  • It requires emergency treatment in hospital, including tests to find the cause.
  • After recovering from encephalitis, you may have ongoing problems such as epilepsy, fatigue or difficulty with memory, balance, hearing or speech.

What is encephalitis?

Encephalitis is an inflammation of the brain. It is usually caused by a virus. It is rare but potentially life-threatening. It can lead to permanent brain damage.

What causes encephalitis?

There are 2 main types of encephalitis: primary and secondary.

Primary encephalitis occurs if a virus infects your brain.

Secondary encephalitis occurs if your immune system reacts to something in your body (such as an infection, vaccine or cancer), and starts attacking your brain cells. This can happen 1 to 3 weeks after an infection or vaccination. It can also occur if you have an autoimmune condition.

Some infections that can cause encephalitis include:

Often no cause is found, and doctors will treat encephalitis without knowing the cause.

What symptoms might I have?

There may be changes in your brain function as a result of encephalitis, which may cause symptoms such as:

  • drowsiness, confusion
  • seizures
  • strange behaviour, personality changes
  • weakness
  • changes in speech, movement or sensation

Other symptoms of encephalitis may include:

Many of these symptoms also happen in other illnesses, such as migraines. If you have some of these symptoms with a fever, encephalitis is more likely to be the cause.

In very severe cases, encephalitis can lead to coma and even death.

If you or your child has symptoms of encephalitis, a seizure or any change in level of alertness, go to the emergency department straight away.

What complications can develop?

After having encephalitis, you might experience ongoing problems for several months. These may include fatigue, headaches, mood changes or problems with memory, concentration, balance, hearing and speech. Sometimes these problems are permanent.

You could also develop epilepsy.

If your child has had encephalitis, it may affect their development.

How is encephalitis diagnosed?

You will probably be admitted to hospital.

To check for encephalitis and to find its cause, you may have a number of tests, such as:

  • an MRI or CT scan of your brain
  • a lumbar puncture to remove some fluid from around your spinal cord, to test it for encephalitis and to check for viruses or bacteria
  • blood tests
  • a swab taken from your nose or throat, or a test of your urine or faeces, to check for viruses
  • an electroencephalogram (EEG)

Occasionally, if someone is not getting better and no cause has been found, they might have a brain biopsy.

What treatment will I need?

You will probably be given fluids and medicines for pain relief. If you are having seizures, you will be given medicine to stop them. If you have a severe infection, you may need help with breathing.

Other treatments will depend on the cause of your encephalitis. You may be prescribed antibiotics or an antiviral medicine. You might also be given a steroid medicine to reduce inflammation or other treatments to lower your immune system’s reaction, if it is overactive.

Once you are better, you may need speech therapy, occupational therapy or physiotherapy to help you manage longer-lasting symptoms.

If your child has had encephalitis, they will need to have a hearing test to check whether their hearing has been affected. Their development should be monitored over time, to check for any areas of difficulty.

Where can I find more information about encephalitis?

For more information, visit the Brain Foundation website.

If you are concerned about encephalitis or not sure what to do, call healthdirect on 1800 022 222 to speak to a nurse, 24 hours a day.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: September 2022

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