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Side effects of radiotherapy

Radiotherapy can cause different side effects, such as tiredness and feeling sick. The side effects you get depend on which part of the body is having treatment, and how much radiotherapy you have. 

The treatment aims to control symptoms and make you feel better. This is called palliative radiotherapy. Your doctor will try to plan palliative radiotherapy so it has as few side effects as possible. 

The side effects

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:

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.

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.   

Radiotherapy to the tummy (abdomen) or pelvic area can cause diarrhoea. Taking a medicine to slow down your bowel or changing your diet can help to reduce diarrhoea. Your radiotherapy department staff or dietitian will give you information about this.

Drink plenty of fluids and let your doctor know if you have frequent diarrhoea.

For a while after having the treatment you might feel that you have to pass urine more often than usual. And you may have a burning feeling when you do. Or you might feel that you can’t wait then you need to go. This is called cystitis.

The treatment temporarily inflames the lining of your bladder. It helps to drink plenty of fluids. You might find that some drinks increase the soreness, such as tea and coffee. You can experiment for yourself and see what works for you. 

Tell your doctor or nurse if you have bladder soreness. They can prescribe medicines to help.

'Just can’t wait' card

You can get a card to show to staff in shops or pubs etc. It allows you to use their toilets, without them asking awkward questions. You can get the cards from Disability Rights UK or the Bladder and Bowel Foundation. They also have a map of all the public toilets in the UK.

Disability Rights UK can also give you a key for disabled access toilets so that you don't have to ask for a key when you are out.

Last reviewed: 
06 Feb 2019
  • Cancer and its management (7th edition)
    Tobias J. and Hochhauser D.
    Wiley-Blackwell, 2015

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