Bowel cancer: managing bowel and dietary changes

by | Bowel Cancer, Cancer Care

bowel changes

After treatment for bowel cancer, many people find that they need to adjust to changes to their digestion or bowel function. Changes to how your bowel or bladder works can be very distressing and difficult to adjust to. These changes may be temporary or ongoing, and may require specialised help. If you experience any of these problems, talk to your GP, specialist doctor, specialist nurse or dietitian.


Incontinence is when a person is not able to control their bowel or bladder. It may be caused by different types of treatment.

Faecal incontinence

The movement of waste through the large bowel can become faster after surgery or radiation therapy. This can mean you need to go to the toilet more urgently and more often. It may also result in a loss of control over bowel movements. Bowel surgery or radiation therapy may weaken the anus, making it difficult to hold on when you feel the need to empty your bowels, particularly if you have loose stools (diarrhoea).

Urinary incontinence

This is when urine leaks from your bladder without your control. Bladder control may change after surgery or radiation therapy. For example, radiation therapy can irritate the lining of your bladder, because the bladder is located near the large bowel. Some people find they need to urinate more often, need to go in a hurry or don’t fully empty the bladder.

If you have bowel or bladder changes, you may feel embarrassed, but there are ways to manage the symptoms. Incontinence issues usually improve in a few months, but sometimes take years. Talk to your health care team about whether any bowel or bladder changes are likely to be permanent.

For ways to manage incontinence:

Talk to your surgeon or GP about available treatments. They may refer you to the hospital continence nurse or physiotherapist, who can suggest exercises to strengthen the pelvic floor muscles.

Call the National Continence Helpline on 1800 33 00 66 to talk to a continence nurse about continence aids, if needed, or visit

Visit to locate public toilets near you. You can also download the National Public Toilet Map App from the App Store (Apple phones) or Google Play (Android phones).

The Australian Government’s Improving Bowel Function After Bowel Surgery booklet provides helpful tips about managing bowel problems. Visit to get a copy, or call 1800 33 00 66.


Diarrhoea, the frequent passing of loose, watery stools, may be caused by different types of treatment:


If you have had part of your bowel removed, your bowel movements may be looser than you were used to. This is because the bowel absorbs water to form your stools. With a shorter bowel, the stools don’t form as solidly as before. This may be ongoing.

Radiation therapy

Diarrhoea is a common side effect of radiation therapy. It can take some weeks to settle down after treatment has finished. For a small number of people, diarrhoea is ongoing.


This can cause diarrhoea and nausea. These side effects will go away after treatment and you can gradually resume a normal diet.

The fast movement of food through your bowel before your body can absorb the water and nutrients can make you dehydrated. Signs of dehydration include a dry mouth, dark urine, dizziness and confusion. If left untreated, this can be dangerous. To manage dehydration, drink plenty of water and consider using a rehydration drink. If your anus becomes sore, a pharmacist can recommend a cream.

Having diarrhoea can also make you feel tired. Try to rest as much as possible and ask family or friends to help out with chores. Talk to your doctor and nurses about ways to control diarrhoea, such as using medicines, changing your diet and replacing fluids. You may also be referred to a dietitian or to a physiotherapist who specialises in bowel function.

Wind (flatulence)

Many people who have treatment for bowel cancer, especially surgery, find that it gives them wind. Reducing the foods that produce wind may be helpful. These might include fruit and vegetables with a high amount of carbohydrates that cannot be digested and absorbed in the intestine.

Diet after treatment

Immediately after treatment – particularly surgery – you may be on a modified diet. During and after recovery from treatment, you may find that some foods cause discomfort, wind or diarrhoea.

Your treatment team may tell you about some foods to avoid, but different foods can affect people differently, so you will need to experiment to work out which foods cause problems for you. It is best to limit – not eliminate – these foods from your diet, as you may find that what you can handle improves over time.

Keeping a food and symptom diary can help. Your ability to handle different foods usually improves with time but can take many months. If you find that dietary fibre makes any bowel problems worse, you may need to eat low-fibre foods.

If you have a stoma, you may need to make some dietary changes in the first few weeks to help the stoma settle. Nuts, seeds and very fibrous foods can lead to a blockage in the stoma. The level of stoma output will vary depending on how much you eat and when you eat. By trial and error, you might identify particular foods that irritate the stoma, but these vary considerably between people.

Most people with a stoma return to their normal diet. If you have concerns, your doctor or stomal therapy nurse may refer you to a dietitian.

Coping with dietary issues


  • Everyone responds to food differently.
  • Try different foods more than once to see how you react.
  • If a food doesn’t cause you any problems, you don’t need to avoid it.
  • If you have ongoing problems with food and eating, talk to your treatment team.
  • You may be able to see a dietitian at your cancer treatment centre – check with your cancer care coordinator.
  • You can also ask your GP for a referral to a dietitian who specialises in cancer. To find an Accredited Practising Dietitian in your area, call 1800 812 942 or visit


  • Eat low-fibre foods, such as white rice, white pasta, white bread, rice-based cereal, potatoes, fish and lean meat.
  • Well-cooked vegetables without seeds, husks or skin, such as carrots, potato and pumpkin, are good choices.
  • Eat three small meals a day and snack often.
  • If you suspect that a food causes diarrhoea, avoid it for 2–3 weeks. Reintroduce one food at a time. If the diarrhoea flares up again, you may want to avoid that food.
  • Avoid foods that increase bowel activity, e.g. caffeine; alcohol; spicy, fatty or oily foods; or artificial sweeteners.
  • Don’t eat too many raw fruits and vegetables, wholegrain breads and cereals, or legumes (e.g. lentils, chickpeas), as they may make diarrhoea worse.
  • Avoid dairy foods if they cause problems, or try low lactose or soy-based dairy products.


  • Stoma blockages
  • Try chewing charcoal tablets, eating natural yoghurt and/or drinking peppermint tea.
  • Cut food into small, bite- sized pieces.
  • Chew your food slowly and thoroughly.
  • When you have a drink, take small sips.
  • Talk to your doctor about doing light exercise to relieve bloating and gas.
  • Avoid foods that increase gas, e.g. eggs, legumes such as lentils and chickpeas, large serves of dairy products, and fizzy drinks.
  • Don’t eat too many raw fruits and vegetables.

Stoma blockages

  • Eat regular meals.
  • Try to maintain a balanced diet so your body is well nourished.
  • Drink up to eight glasses of fluid a day so you stay well hydrated.
  • Cut food into small, bite- sized pieces, and chew slowly and thoroughly.
  • If you have trouble eating a certain food, talk to a dietitian about alternatives.
  • You may find cooked food easier to digest.
  • Some foods are more likely to cause blockages in some people. These include high-fibre foods, raw vegetables, fruit and vegetable skins, nuts, seeds, kernels (e.g. corn, popcorn), and sausage skins.
  • Try small amounts of a new food. If it’s okay, try more next time.

Key points about changes to bowel function

Having a stoma

Some people will need to have a stoma, which is a surgically created opening in the abdomen. Waste (faeces or stools) passes out of the body through this opening and is collected in a bag. A stoma may be temporary or permanent.

Common changes

After treatment for bowel cancer, most people find their bowel function changes. You may have trouble controlling your bowel or bladder, have diarrhoea, or suffer from wind.

Managing changes

  • Stomal therapy nurses and stoma associations can provide support and information to help you adjust to life with a stoma.
  • There are many ways to manage incontinence, and changes to bowel and bladder function. For support and information, talk to your treating doctors.
  • Drinking plenty of fluid throughout the day will help avoid dehydration and reduce constipation and blockages.
  • You may need to change your diet, especially if the diarrhoea or wind is ongoing, or if you have a stoma blockage.
  • A dietitian can give you advice on removing certain foods from your diet, and tell you if and when to reintroduce them.