Worsening symptoms

Radiotherapy to the brain causes a short term swelling in the treatment area, which raises the pressure in the brain.

Doctors call this oedema. It can make your symptoms worse for a time. This can be frightening because you might think the radiotherapy isn't working. Raised pressure in the brain might cause:

  • headaches
  • feeling sick
  • fits (seizures)

Controlling symptoms

The swelling from radiotherapy goes down after treatment, but while you have it your doctor gives you medicines to take. 


Steroids can reduce the swelling in the brain.

Your doctor will tell you how long to take the steroids for. Usually, you gradually lower the dose of steroids after the treatment ends. But if the swelling hasn't gone down enough, your symptoms might start to come back.

It is important to talk to your radiotherapy doctor (clinical oncologist), radiographer, or specialist nurse if you think your symptoms are getting worse.

They will be able to reassure you and might increase your dose of steroid tablets until it gets better.

Bevacizumab (Avastin)

You might have a targeted cancer drug called bevacizumab (Avastin) if you can't take steroids for any reason.

Bevacizumab can lower raised pressure in the brain by changing the growth of blood vessels around the tumour.

  • Leibel and Phillips Textbook of Radiation Oncology (3rd edition)
    R Hope and others, 
    Elsevier Saunders, 2010

  • Cancer and its management (7th edition)
    J Tobias and D Hochhauser
    Wiley-Blackwell, 2015

  • Electronic Medicines Compendium
    Accessed November 2020

Last reviewed: 
10 Nov 2020
Next review due: 
10 Nov 2023

Related links