Abdominal or pelvic radiotherapy side effects

You may have radiotherapy to the area in between your hips (the pelvis) or to the tummy (abdomen).

The main side effects from abdominal or pelvic radiotherapy include:

  • diarrhoea
  • sickness
  • weight loss
  • bladder problems
  • pain
  • changes to your sex life and fertility

You may also experience more general side effects of radiotherapy such as sore skin and tiredness.

Like all side effects of radiotherapy, you might not feel these straight away. Side effects tend to come on gradually as you go through your treatment. And for a few weeks afterwards. These usually get better within a few weeks of finishing your radiotherapy treatment. Everyone reacts differently to radiotherapy, so how you feel varies from person to person. 


It is normal to have diarrhoea Open a glossary item during or after radiotherapy to your abdomen or pelvis. You might also have stomach cramps and wind. Diarrhoea can also be a long term side effect. This means it can continue for quite a while after your treatment ends.

It is unpleasant to have diarrhoea and it can also make you feel weak and tired, so it is important to rest if you need to. 

Your bowel habit may change during radiotherapy and following treatment. You might:

  • need to open your bowels urgently
  • have to go several times before you feel the bowel is empty
  • feel the need to open your bowels, even if you have done so recently and have an empty bowel (tenesmus)
  • pass more wind than usual
  • pass mucus Open a glossary item from your back passage

More rarely you might notice some blood in your poo. This can sometimes be due to irritation of the rectum lining because of opening your bowels more. Let your doctor or radiographers know if you have any bleeding. 

There are several things that can help you, such as:

  • anti diarrhoea drugs, which your healthcare team can give you
  • anti spasm medicines from your healthcare team
  • drinking lots – this is important as you can easily get dehydrated
  • changing your diet – you can speak to your radiotherapy team or dietitian Open a glossary item for advice


Radiotherapy to the abdomen can make you feel or be sick. This is called nausea and vomiting. The sickness might last for a few weeks after the treatment has finished. Medicines, diet and sometimes complementary therapies Open a glossary item can help to control sickness.

Sickness can usually be well controlled with medicines. Your radiotherapy doctor can prescribe anti sickness tablets for you to take. Some people find that it helps to take an anti sickness tablet about 20 to 60 minutes before having treatment.

Other people find they manage better by taking anti sickness tablets regularly throughout the day. They do this during the course of their treatment. You can discuss which would be best for you with your radiotherapy team.

There are some foods which can help reduce your sickness, such as ginger, and others which are best to avoid.

Weight loss

Sickness or problems eating can cause you to lose weight. You may feel tired and weak. Sometimes you might not feel like eating at all. The dietitian or your doctor can give you advice if eating is a problem. 

If your weight keeps on falling you might need to spend a short time in hospital. You might have liquid food through a fine tube called a nasogastric tube Open a glossary item. It goes up your nose and down into your stomach. Or you might have a special liquid feed into your bloodstream through a drip.

Bladder problems

Having radiotherapy to the pelvis might cause:


You might have pain in your pelvis after radiotherapy. This can happen some time after your radiotherapy has finished. Let your healthcare team know if you have any pain during or after your treatment. 

Possible reasons for pain can include: 


Radiotherapy to your lower abdomen or pelvis can affect your fertility and sex life.

For women, radiotherapy to this area may affect your womb and can stop your ovaries from working. If you haven’t already been through the menopause, this means your periods stop. So you won’t be able to become pregnant. 

The risk of infertility depends on:

  • the dose of radiation to your ovaries
  • your age - the risk is higher the older you are
  • whether you have chemotherapy with the radiotherapy

Finding out that treatment for your cancer may leave you infertile can be extremely distressing if you had hoped to get pregnant in the future. Your doctor, radiographer and nurse will support you and talk about possible options.

Radiotherapy can also cause vaginal dryness, fibrosis and narrowing of the vagina. The skin inside the vagina can also become thin, delicate and easily torn. This can cause pain and discomfort. You may find that you feel too sore to have sex comfortably.

For men, the effect on fertility can be temporary or permanent and means you might not be able to father a child in the future. Your doctor or radiographer will talk to you about this before your treatment. They can support you and talk about the possibility of storing your sperm (sperm banking).

It is common for men having pelvic radiotherapy to have some problems with sex. You might have some of the following issues:

  • loss of interest in sex
  • sharp pain when you ejaculate
  • erection problems

You may have to wait several weeks after radiotherapy before you can have sex. Your doctor or radiographer can give advice about this.

You may not feel emotionally ready for much longer than this. Having cancer and its treatment can affect how you feel about your body, you may have ongoing side effects or other changes that may be affecting your body image. Talk to your partner about how you feel.

This video shows people affected by cancer talking about the side effects of radiotherapy for pelvic or abdominal cancer. The video is around 5 and a half minutes long.

You can talk to the Cancer Research UK nurses for general information and support on freephone 0808 800 4040, from 9am to 5pm, Monday to Friday.

  • Devita, Hellman and Rosenberg's Cancer: Principles and Practice of Oncology (12th edition)
    VT Devita, TS Lawrence and SA Rosenberg
    Wolters Kluwer Health, 2023

  • External Beam Therapy (Radiotherapy in Practice) Third Edition
    Peter Hoskin
    Oxford University Press, 2019

  • Cancer and its Management (7th edition)
    J Tobias and D Hochhauser
    Wiley Blackwell, 2015

  • Walter and Miller's Textbook of Radiotherapy: Radiation Physics, Therapy and Oncology (8th edition)
    R Symonds, J A Mills and A Duxbury
    Elsevier, 2019

Last reviewed: 
30 Jan 2024
Next review due: 
30 Jan 2027

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