Treating encephalitis 

Encephalitis needs to be treated urgently and most people with the condition will be admitted to a hospital intensive care unit (ICU).

Treatment depends on the type of encephalitis you have, but aims to:

  • stop and reverse the process of infection
  • control immediate complications caused by fever, such as seizures or dehydration
  • prevent long-term complications developing

An oxygen mask will be used to help with breathing. Feeding tubes will provide nutrition and help keep the body hydrated.

Encephalitis is a very serious condition and recovery can take months. There's also a significant risk of developing complications of encephalitis, such as memory loss, behavioural changes or even death.

Infectious encephalitis

In the UK, a medicine called aciclovir (sometimes spelt acyclovir) is the most widely used treatment for infectious encephalitis. However, it's only effective in treating cases caused by the herpes simplex virus or varicella zoster virus.

The earlier aciclovir is used, the more successful it is, so treatment is usually started while the condition is being diagnosed. If tests reveal encephalitis is being caused by something else, the treatment will be changed.

Aciclovir works by directly attacking the DNA inside viral cells, which stops the virus reproducing and spreading further into the brain. It's given directly into a vein (intravenously), usually three times a day for two to three weeks.

Aciclovir causes some side effects, include vomiting and diarrhoea. Less commonly, it can lead to liver damage, hallucinations and a decrease in the number of white blood cells produced by the bone marrow, which can make you more vulnerable to infection.

In rare cases, where a bacterial or fungal infection causes encephalitis, treatment usually consists of antibiotics or antifungal medicines.

Post-infectious encephalitis

Post-infectious encephalitis is usually treated with injections of high-dose corticosteroids. This may last several days, depending on the severity of the condition.

Corticosteroids work by calming the immune system (the body's natural defence against infection and illness). This reduces the levels of inflammation inside the brain.

Some people's symptoms may improve a few hours after treatment. However, in most cases, it will take a few days before symptoms start to improve.

Side effects of corticosteroids include:

  • nausea and vomiting
  • indigestion
  • skin irritation at the site of the injection
  • rapid mood changes, such as feeling happy one moment and depressed the next

If your symptoms don't respond to treatment with corticosteroids, an additional medication called immunoglobulin therapy may be used. This comes from a blood donation and contains specific antibodies that help to regulate the immune system.

If your symptoms still don't improve, a therapy called plasmapheresis may be considered. Plasmapheresis involves gradually passing your blood through a machine to remove the parts that contain antibodies before it's returned to your body.

Autoimmune encephalitis

Autoimmune encephalitis can be treated with corticosteroids, immunoglobulin therapy and plasmapharesis. An additional medication known as an immunosuppressant may also be recommended. 

Immunosuppressants suppress your immune system, which should prevent it attacking healthy tissue. Ciclosporin is an immunosuppressant that's widely used to treat autoimmune encephalitis.

Common side effects of ciclosporin include:

Chronic encephalitis

There's currently no cure for the subacute sclerosing panencephalitis (SSPE) type of chronic encephalitis. Anti-viral medication can slow its progression, but this condition inevitably proves fatal within two years of being diagnosed.

The recommended treatment for the type of chronic encephalitis known as progressive multifocal leukoencephalopathy (PML) usually depends on what's causing the immune system to weaken.

If the immune system is weakened due to a treatment such as chemotherapy, this treatment may be temporarily withdrawn.

If your immune system is weakened due to an HIV infection, a type of medication known as highly active antiretroviral therapy may be effective.

Read more about treating HIV.

If used early, HIV medication can also be an effective treatment for chronic progressive HIV encephalitis. If left untreated, it's fatal.

Page last reviewed: 16/12/2014

Next review due: 16/12/2016