Bowel changes after treatment

Treatment for bowel (colon and rectal) cancer can cause changes to how your bowels work. Changes can include how often you poo, how urgently you need to go, and difficulty emptying your bowel completely.

These effects usually improve in the weeks and months after you finish treatment. But sometimes they might go on for longer and be difficult to live with. There are things you can do to help you manage these changes.

The bowel changes you have after treatment will depend on a number of factors. These include what operation you have, which part of your bowel the surgeon removes and any other treatments you have.  Your doctor or nurse will tell you more about what to expect after treatment and help you manage any bowel changes.

How treatment affects how your bowels work

The changes to your bowel function will depend on what treatment you have. Side effects are likely to be worse if you have a combination of treatments.

Surgery to the large bowel (colon)

The body absorbs water from undigested food as it passes through the colon. The waste material (poo) is then stored in the back passage (rectum) until you pass it out of the body through your anus. Straight after surgery to remove part of your colon, your poo might be a bit looser and more frequent. But this usually settles down after a few weeks and medicines may help with some of the symptoms.

Surgery to the back passage (rectum)

The rectum stores poo before you pass it out of your body. Most people will have problems with their bowel function for several weeks after rectal cancer surgery. And for many, these problems can continue for around a year. Although it is unlikely that your bowel habits will return to how they were before surgery, these problems should become less severe with time.

But some people can develop a long term condition called low anterior resection syndrome, or LARS. This syndrome is a group of bowel problems after surgery for rectal cancer. These problems can include:

  • opening your bowels more often (frequency)
  • getting a strong urge to open your bowel and constantly feeling like you need to poo (urgency)


Diarrhoea is a side effect of some chemotherapy drugs.


Radiotherapy to the rectum can inflame the lining of the bowel. This can cause bleeding and looser, more frequent bowel movements. Side effects often get better within a few weeks of finishing treatment. But some people have these side effects months or even years later.

How you might feel

Bowel changes might include:

  • pooing more often
  • changes to your poo such as loose runny poo (diarrhoea) or hard, difficult to pass poo (constipation)
  • having little or no warning that you need to poo or pass wind
  • passing wind and feeling bloated
  • leaking poo or being unable to control when you go
  • difficulty emptying your bowel completely when you poo
  • constantly feeling like you need to poo
  • sore skin around your anus

You might also have a temporary or permanent stoma.  This means the surgeon has brought out the end of your bowel into an opening on your tummy (abdomen). The opening is called a stoma.

You should speak to your doctor or specialist nurse if you’re having any of these side effects. They can advise you about what you can do to help manage these changes.

What can I do to help?

Your bowel habits might never return to how they were before your cancer treatment. But things should settle so that you develop a new ‘normal’ pattern. It might feel difficult at first. But remember that it’s likely to get better over time.

You can make some changes to help lessen the effects of treatment.


What you eat can make your poo looser or give you more wind. You might need to experiment a bit to find out which foods upset you. Everyone is different and there are no set rules about what you should eat. But the foods most likely to cause problems are:

  • very high fibre fruits and vegetables
  • onions, brussel sprouts and cabbage
  • pulses such as baked beans or lentils
  • fizzy drinks, beer and lager
  • very rich or fatty foods

You can slowly increase different foods in your diet and see how your bowels cope. If you find a food upsets your bowels, you can cut it out and try it again after a few weeks. Ask to see a dietitian if you have problems. They can give you tips and help you to work out which foods upset you.


Your doctor or nurse might recommend that you take medicines to help your bowels. Talk to your doctor before you take any of these medicines.

Loperamide (Imodium) can help if you have frequent, watery poo. It works by slowing down your bowel so it takes longer for poo to pass through. This gives the bowel more time to absorb water so the poo is less runny. It can also reduce how often you need to go.

Your doctor might also suggest fybogel. This helps to bulk out loose poo and can help if you are pooing small amounts frequently.

For constipation, your doctor might give you stool softeners or laxatives.   

Skin care

Pooing more often can make the skin around your back passage sore. You should try to keep it as clean and dry as possible. Your doctor might recommend creams such as E45 or sudocrem.  

Other tips include:

  • after pooing, wipe gently with soft toilet paper
  • wash the skin with tepid water and simple soaps – don’t use perfumed or medicated soaps or other products
  • pat dry the skin with a soft towel – or you can use a hairdryer on a cool setting
  • wearing loose, comfortable underwear and clothing can help

Toileting habits - bowel function after treatment

Your nurse specialist or doctor might talk to you about your toileting habits. These habits include how long you spend on the toilet and at what point you go to the toilet when you feel the urge.

Try not to sit and strain on the toilet for long periods – speak to your nurse or doctor if you find you’re doing this. And try to hold on until the urge to poo is strong. This might be difficult at first. But over time you will become more familiar with how long you can hold on before you have an accident.  


Living with bowel changes

Being prepared when you go out

One of the hardest things about having diarrhoea is that it can sometimes happen very suddenly. To avoid or cope with accidents when you go out, you can help to prepare yourself: 

  • know exactly where the toilets are in the place you are going
  • contact the Bladder and Bowel Foundation or Pelvic Radiotherapy Disease Association for a 'Just can't wait' card to give you quick access to public toilets
  • take spare underwear, pads, soothing creams and a plastic bag with you, just in case

Gentle exercise

Regular exercise helps to keep your bowel working normally.

Side effects from your cancer and its treatment can make it difficult to exercise. You might feel that you don’t have the energy for it. But a little exercise is better than none.

A short walk each day may make all the difference to keeping your bowel motions soft and regular. Exercise has also been shown to increase energy levels, so you may gradually feel better and be able to do a little more.

Support and information

You may feel quite isolated and find it difficult to talk to people. Our bowels and going to the toilet are very private matters for many people. But the staff at the hospital or clinic are very used to talking about these things and so you don't need to feel embarrassed. It is up to you who you decide to talk to.

You can talk to your doctor or nurse about any of these changes, particularly if your symptoms aren’t getting better. They can offer you advice and information about what you can do to manage your bowels.

They might refer you to a specialist such as a continence specialist or doctor who specialises in the digestive system (gastroenterologist).

Some people find it helpful talking with other people who have had similar experiences. You can do this in person at support groups, or online using forums.

Last reviewed: 
07 Nov 2018
  • American Cancer Society Colorectal Cancer Survivorship Care Guidelines (September 2015)
    K El-Shami and others
    CA Cancer J Clin. 2015 Nov-Dec; Volume 65 Issue 6 Pages 428-55

  • A descriptive qualitative study to assess patient experiences following stoma reversal after rectal cancer surgery
    M Reinwalds and others
    Ostomy wound management 63 (12) December 2017

  • Health-related quality of life after colorectal cancer in England: a patient-reported outcomes study of individuals 12 to 36 months after diagnosis.
    A Downing
    Journal of Clinical Oncology  SHAPE  \* MERGEFORMAT 2015 Feb Volume 33 Issue 6 Pages 616-24

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