Possible side effects of radiotherapy

You may develop side effects while you’re having radiotherapy. These usually improve in the weeks and months after treatment finishes. Your health care team will discuss possible side effects with you. Do let them know if you have side effects as there are often ways to help.

Side effects you may have include:

  • skin changes
  • tiredness
  • stomach cramps
  • vaginal discharge
  • a reduction in red and white blood cells – you may need regular blood tests
  • bowel changes, including diarrhoea and soreness around the back passage
  • bladder changes, including a burning feeling when you pass urine and feeling like you want to pass urine more often.

Radiotherapy to the pelvic area can sometimes cause side effects months or years after radiotherapy treatment. These side effects may include changes to the bowel and bladder, changes to the vagina and lymphoedema (swelling) in one or sometimes both legs.

Do let your health care team know if you notice any of these changes as there are lots of ways in which they can be managed.

Side effects of radiotherapy

You may develop side effects over the course of your treatment. These usually improve gradually over a few weeks or months after treatment finishes. Your doctor, nurse or radiographer will discuss this with you, so you know what to expect. Let them know about any side effects you have during or after treatment, as there are often things that can be done to help.


The side effects of radiotherapy are made worse by smoking, so if you can cut down or stop smoking during and after your treatment this will help. If you want help or advice on how to quit, you can talk to your clinical oncologist, GP or a specialist nurse. Organisations such as QUIT can also offer advice and support.

Skin changes

Your skin in the area being treated may get dry and irritated. Avoid using perfumed soaps or bodywashes during your treatment as they could irritate your skin. You’ll be given advice on looking after your skin. Your doctor or sometimes your radiographer or nurse can prescribe cream to soothe it if it becomes sore.

You may lose some of your pubic hair. After treatment, it will usually grow back, but may be thinner than it was before.


This is a common side effect and may continue for some months after treatment is over. During treatment, you may need to rest more than usual, especially if you have to travel a long way for treatment each day. But it’s good to do gentle exercise, such as walking, when you feel able. Once your treatment is over, gradually increase your activity and try to balance rest periods with exercise such as walking. This will help build up your energy levels.

‘It’s incredible that you’re just lying there during radiotherapy and almost feel like nothing’s happening, but it really drains your energy.’

Understanding cervical cancer

Bowel changes

Radiotherapy to the pelvis may irritate your bowel and cause your bowels to open more often. You may have diarrhoea and also soreness around the back passage.

Make sure you drink plenty of fluids if you have diarrhoea. Eating a low-fibre diet may help reduce diarrhoea. This means avoiding wholemeal bread and pasta, raw fruit, cereals and vegetables during and for a couple of weeks after treatment. Your doctor, nurse or radiographer can provide you with information on diet. They may refer you to a dietitian. Your doctor may also prescribe medication to help manage diarrhoea.

Stomach cramps

Radiotherapy to the pelvis can cause stomach cramps. If you experience these, it’s important to mention them to your doctor, nurse or radiographer. They can advise you on medication to help.

Changes in your blood

Sometimes external radiotherapy can temporarily reduce the number of red and white blood cells produced by your bone marrow. This is more likely to happen if you are having chemoradiation. If your white blood cell count is low you’re more prone to infection and may need antibiotics. If your red blood cell count is low you may get tired more easily and you may need a blood transfusion. Your hospital team will arrange for you to have regular blood tests if needed.

Bladder changes

Radiotherapy can irritate your bladder, which will make you want to pass urine more often. It may also cause a burning feeling when you pass urine. Your doctor can prescribe medicines to reduce these symptoms. It will also help to drink at least 2 litres (3 pints) of fluid a day.

Vaginal discharge

You may have a slight vaginal discharge for a few weeks after treatment has finished. If it continues or becomes heavy, let your doctor, specialist nurse or radiographer know.

Find out more about pelvic radiotherapy.

Possible late effects

Radiotherapy to the pelvic area can sometimes cause long-term side effects (late effects). However, improvements in how radiotherapy is given have reduced the risk of some late effects. If you do have any late effects there are lots of ways in which they can be managed or treated.

Changes to the vagina

Radiotherapy to the pelvic area can cause vaginal dryness and narrow the vagina, which can make having sex or an internal examination uncomfortable. Your specialist nurse or radiographer will usually talk to you about ways of trying to prevent narrowing (such as using vaginal dilators) and creams to treat dryness.

Changes to the bowel or bladder

Some women may develop permanent changes to the bowel or bladder. Symptoms generally develop from six months to two years after radiotherapy treatment, although in some people it may be years later. If your bowel is affected, you may have to go the toilet more often than usual, or you may have diarrhoea.

Sometimes, the bladder shrinks after radiotherapy and can’t hold as much, so you’ll need to pass urine more often. The blood vessels in the bowel and bladder can become more fragile, and if this happens you may get blood in your urine or bowel movements.

Always let your doctor, radiographer or specialist nurse know if you have any changes to your bladder and bowel so they can be checked out.


Radiotherapy and surgery to remove the pelvic lymph nodes may increase the risk of swelling (lymphoedema) in one, or occasionally both, legs. This isn’t common, but you can read about ways to reduce the risk of lymphoedema here. Your doctor, radiographer or specialist nurse can also give you information and support.

Back to Radiotherapy explained

Planning your treatment

Before you start radiotherapy, your treatment is carefully planned with information from a planning scan.

Who might I meet?

You will meet many different specialists before, during and after radiotherapy treatment.

After treatment

It can take time for your body to recover after finishing treatment. Advice and support is always available.