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Side effects of radiotherapy

Find out what the side effects of external radiotherapy are and how to cope with them.

Side effects tend to start a few days 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.

Everyone is different and the side effects vary from person to person. You may not have all of the effects mentioned.

Side effects can include:

You might feel very 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.

Long term side effects

Most side effects gradually go away in the weeks or months after treatment. But some side effects can continue or might start some months or years after your treatment has finished.

Normal tissues grow very slowly so the effects of the radiation take a long time to show up. You may find you have bowel changes or need to pass urine more often.

Doctors can't usually tell who will be most at risk of side effects. Some people just seem to be more sensitive to radiation than others. Research is going on to try to find a way of telling this in advance so that those people can have lower treatment doses.

Tell your doctor if you have had bowel disease or previous surgery to the abdomen. They may then be able to take precautions to reduce your risk of side effects. If you are worried about long term side effects, you should certainly ask your doctor about the risks from your treatment.

Rarely, you may have more frequent or looser poo (stools) in the long term. This can be all the time. Or it may come and go.

Your doctor can give you medicines to slow down the bowel and help control the diarrhoea. You might need to avoid high fibre foods. 

Let your doctor know if you have ongoing problems with frequent bowel movements or bleeding. They can refer you to a specialist team. The team includes cancer doctors, digestive system specialists, bowel surgeons, dietitians and specialist nurses.

The team can carry out tests to see what is causing the problem. Then they can give you treatment to control it.

The Pelvic and Radiation Disease Association offers information and support for people suffering from the long term side effects of pelvic radiation.

'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.

Radiotherapy can make your bladder less stretchy so it won't hold as much urine as it used to and you will have to go to the toilet more often.

Do tell your doctor who may be able to refer you to a nurse who specialises in continence problems. With help, you may be able to train your bladder so that you can pass urine a little less often.

Last reviewed: 
05 Dec 2016
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  • Newly diagnosed and relapsed epithelial ovarian carcinoma: ESMO clinical practice guidelines for diagnosis, treatment and follow up
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