Encephalitis is an uncommon but serious condition in which the brain becomes inflamed (swollen).
It can be life-threatening and requires urgent treatment in hospital.
Anyone can be affected, but the very young and very old are most at risk.
Symptoms of encephalitis
More serious symptoms develop over hours, days or weeks, including:
- confusion or disorientation
- seizures (fits)
- changes in personality and behaviour
- difficulty speaking
- weakness or loss of movement in some parts of the body
- loss of consciousness
Dial 999 for an ambulance immediately if you or someone else has these more serious symptoms.
Causes of encephalitis
It's not always clear what causes encephalitis, but it can be caused by:
- viral infections – several common viruses can spread to the brain and cause encephalitis in rare cases, including the herpes simplex virus (which causes cold sores ↗ and genital herpes ↗) and the chickenpox ↗ virus
- a problem with the immune system (the body's defence against infection) – sometimes something goes wrong with the immune system and it mistakenly attacks the brain, causing it to become inflamed
- bacterial or fungal infections – these are much rarer causes of encephalitis than viral infections
You can't catch encephalitis from someone else.
Read more about the causes of encephalitis ↗.
Treatments for encephalitis
Encephalitis needs to be treated in a hospital. The earlier treatment is started, the more successful it's likely to be.
Treatment depends on the underlying cause, but may include:
- antiviral medication
- steroid injections ↗
- treatments to help control the immune system
- antibiotics ↗ or antifungal medication ↗
- painkillers to reduce discomfort or a fever
- medication to control seizures (fits)
- support with breathing, such as oxygen through a face mask or a breathing machine (ventilator)
How long someone with encephalitis needs to stay in hospital can range from a few days to several weeks or even months.
Read more about how encephalitis is treated ↗.
Recovering from encephalitis
Some people will eventually make a full recovery from encephalitis, although this can be a long and frustrating process.
But many people never make a full recovery and are left with long-term problems due to damage to their brain.
Common complications include:
- memory loss ↗
- frequent seizures
- personality and behavioural changes
- problems with attention, concentration, planning and problem solving
- persistent tiredness
These problems can have a significant impact on the life of the affected person, as well as their family and friends. But help and support is available.
Read more about the complications of encephalitis ↗.
It's not always possible to prevent encephalitis, but some of the infections that cause it can be prevented with vaccinations.
These include the:
- MMR (measles, mumps and rubella) vaccine ↗ – a routine vaccination offered to all children in England
- Japanese encephalitis vaccine ↗ – recommended for travellers to at-risk areas, such as parts of Asia
- tick-borne encephalitis vaccine ↗ – recommended for travellers to certain parts of Europe (but not the UK) and Asia
- rabies vaccination ↗ – recommended for travellers to at-risk areas ↗ where access to medical care is likely to be limited
Speak to your GP if you're not sure whether your vaccinations are up to date, or you're planning to travel abroad and don't know if you need any vaccinations.