Brain radiotherapy and tiredness | Cancer Research UK
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Brain radiotherapy and tiredness

Nurse and patients talking about cancer

This page tells you about tiredness during and after having radiotherapy to the brain. Find out about


Tiredness due to brain radiotherapy

Radiotherapy to the brain can make you feel very tired. You might have radiotherapy for

  • A tumour that started in the brain (a primary brain tumour)
  • Cancer cells that have spread into the brain from another part of the body (secondary brain tumour)

You may not feel tired at the beginning of your treatment. The tiredness usually comes on gradually as you go through your treatment over a number of weeks. By the end of the course of treatment you may feel very tired.

The tiredness is a direct effect of the treatment. It is due to the body using up your energy reserves to repair healthy cells damaged by the radiotherapy. If you are taking steroids these can also cause tiredness, particularly when you stop taking them. 

Travelling to the hospital for treatment can also make you tired. Unfortunately, the tiredness does not go away immediately when the treatment ends. It usually carries on for at least 6 weeks.

In a few people, the tiredness can become very severe a few weeks after treatment has finished. You may also feel drowsy and irritable. This is a rare side effect and is called somnolence syndrome. It doesn't need treatment and gets better on its own over a few weeks.


Coping with tiredness

If you are tired, it is important to rest or sleep when you need to. But it is likely to help if you can get some regular exercise. A daily walk is good if you can manage it.


Getting help and information

Find out about

Brain tumours

Books and resources about brain tumours

Brain tumour organisations

External radiotherapy

Side effects of radiotherapy

Tips on coping with tiredness

For general information and support

Contact the Cancer Research UK nurses on freephone 0808 800 4040 (Open 9am to 5pm, Monday to Friday)

Share experiences on our online forum – Cancer Chat

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Updated: 14 March 2016