Decorative image

Side effects of radiotherapy

Find out about the side effects of brain tumour radiotherapy and how to cope with them.

Side effects tend to start a week after the radiotherapy begins. They gradually get worse during the treatment and for a couple of weeks after the treatment ends. But they usually begin to improve after around 2 weeks or so.

These side effects vary from person to person. You may not have all of the effects mentioned.

Side effects can include:

Hair loss only happens in the area of the head that is being treated. You do not lose all your hair as you do with some cancer drugs. You usually only lose patches of hair where the radiation beams entered and left your skull.

You might feel tired during your treatment. It tends to get worse as the treatment goes on. You might also feel weak and lack energy. Rest when you need to.

Tiredness can carry on for some weeks after the treatment has ended but it usually improves gradually.

Various things can help you to reduce tiredness and cope with it, such as exercise. Some research has shown that taking gentle exercise can give you more energy. It's important to balance exercise with resting.

A rarer complication is somnolence syndrome or early delayed syndrome. This is extreme tiredness where you sleep nearly all the time. You might have other symptoms. For example, a worsening of your old symptoms or a poor appetite. 

Somnolence syndrome is more common in children, but can also happen in adults. It usually starts 4 to 6 weeks after treatment has finished. Just when you think you are getting over your treatment, this can be a blow. But it also passes in time.

Your doctor might temporarily increase your dose of steroids to reduce somnolence syndrome.

Radiotherapy for brain tumours can sometimes make symptoms worse before they get better. This is because the treatment can cause swelling in the treatment area. The swelling increases the pressure in the head and makes the symptoms worse. Your doctor might give you steroids to try to prevent this. Your symptoms usually get better in time.

You might feel sick at times. You can have anti sickness medicines. Let your treatment team know if you still feel sick, as they can give you another type.   

Side effects of stereotactic radiotherapy

Stereotactic radiotherapy and radiosurgery target the radiotherapy very precisely at the brain tumour. So a much smaller area of healthy brain tissue is exposed to radiation.

This means that the treatment tends to have fewer or milder side effects, than regular radiotherapy to the brain.

Long term side effects

Most side effects gradually go away in the weeks or months after treatment. But some side effects can continue, or start some months or years later.  

Last reviewed: 
22 Oct 2015
  • Cancer and its management (7th edition)
    J Tobias and D Hochhauser
    Blackwell, 2015

  • CNS complications of radiotherapy and chemotherapy
    Soussain C. and others
    2009, Nov. Volume 374, Issue 9701, Pages 1639–1651

  • Guidelines on the diagnosis and management of primary CNS and intra-ocular lymphoma (PCNSL)
    British Neuro-Oncology Society, June 2011 

  • Improving outcomes for people with brain and other CNS tumours
    National Institute for Health and Clinical Excellence, June 2006

  • Supportive care in Radiotherapy
    Faithfull S. and Wells M.
    Elsevier Science Limited, 2003

Information and help

Dangoor sponsorship

About Cancer generously supported by Dangoor Education since 2010.