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.

Your skin might go red or darker in the treatment area. You might also get slight redness or darkening on the other side of your body. This is where the radiotherapy beams leave the body.  It's not likely to be that noticeable for bladder cancer but do tell your radiographer if you notice any skin changes.

The red or darker areas can feel sore. Using a cream helps keep the skin hydrated and soothe it. The soreness usually goes away within 2 to 4 weeks of ending the treatment. But your skin might always be slightly darker in that area.

Your radiographers will tell you which cream you should use.

You may feel:

  • as if you want to pass urine all the time (but when you go, there isn't much there)
  • as if you have a bladder infection (cystitis)
  • a burning or stinging pain when you do pass urine

You should try to drink more fluids than you would normally.  Drinking tea and coffee don’t count as they make you go to the toilet and don’t hydrate you.

Many people think that drinking cranberry juice can be helpful with bladder problems. But cranberry juice can increase the effects of warfarin (a blood thinner or anticoagulant). You should not drink cranberry juice if you are taking warfarin. 

It's quite common to have a tube into your bladder (catheter) to help you pass urine during your radiotherapy treatment. 

Your bladder inflammation should settle down after the treatment is over.

Tell your doctor if you have any pain when passing urine. It could be a sign that you have an infection. You may need antibiotic treatment.

Radiotherapy can inflame the lining of your bowel. This can cause diarrhoea. You may also have:

  • griping or cramping pain
  • an increase in wind
  • feeling you need to go to the toilet urgently
  • some mucus or blood in your poo (stool)

It’s important to drink plenty if you have diarrhoea, so you don't become dehydrated. Your doctor might prescribe tablets to help slow down your bowel if you need them. This should help to reduce the number of times you have diarrhoea.  Changing your diet might also help lessen the number of times you need to go, such as a low fibre diet. Ask your nurse or doctor about this.

Ask your nurse or radiographer for soothing creams to apply around your back passage (anus). The skin in that area can get very sore and might break if you have severe diarrhoea.

Diarrhoea should gradually get better a few weeks after your treatment has finished. Let your doctor or nurse know if it continues.

Changes to your sex life

You can have some changes that can affect your sex life. These changes may continue some time after treatment. 

Men can experience a lower sex drive, difficulty in getting an erection or problems with ejaculation.

Women may have dryness and shrinkage of the vagina, making sex painful. Some women also experience an early menopause.

Both men and women might lose their fertility.

Talk to your doctor if you think you have developed any of these side effects.

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 later.  

Side effects of chemoradiotherapy

Having chemotherapy combined with radiotherapy (chemoradiotherapy) can make some side effects worse.

Last reviewed: 
21 Jun 2019
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  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. Please contact patientinformation@cancer.org.uk with details of the particular issue you are interested in if you need additional references for this information.

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