Bowel problems

Cancer and its treatment can irritate your bowel causing increased wind (flatulence), constipation and diarrhoea.

Increased wind (flatulence)

If too much wind is a problem it may help to:

  • avoid drinking through a straw • avoid chewing gum
  • limit fizzy drinks, or let them go flat first
  • limit ‘gassy’ vegetables such as cabbage, onions, cucumber, peas, lentils, and beans.


Poor appetite, being less active than usual, and side effects of treatment can cause constipation (difficulty pooing).Eating regular meals, having enough fibre, drinking plenty of fluid, and keeping active will all help to keep your bowel working properly.

The following tips may help to keep your bowel motions regular. 

  • Drink plenty of fluid (8 to 10 glasses – 1.5 to 2 litres daily).
  • Choose high-fibre breakfast cereals such as porridge, Weet-Bix, and All-Bran.
  • Increase your fibre intake by adding two or three teaspoons of wheat bran flakes to cereals.
  • Choose wholegrain breads and cereals such as brown rice.
  • Aim to eat at least two servings of fruit and three servings of vegetables (1.5 cups) daily if you can.
  • Include some cooked dried beans and/or peas such as kidney beans, chickpeas and lentils, nuts and/or seeds in your diet.
  • Try natural laxatives such as kiwifruit, prunes, and/or their juices.
  • Exercise daily such as by walking, biking, and doing yoga.
  • Check with your treatment team about using a laxative, stool softener, and/or fibre supplement if constipation continues to be a problem.



Infections, some medications, and cancer treatments can harm or irritate your bowel causing diarrhoea and loose watery bowel motions (poo). Watch for signs of dehydration such as increased thirst, dry mouth, feeling tired, having a headache, and weeing less.

  • Take anti-diarrhoea medication if it is prescribed by your treatment team.
  • Drink more to replace lost fluids, at least 8-10 glasses (1.5 to 2 litres) of clear fluid daily such as vegetable juice, clear soup, weak tea, or fruit juice. Do not have undiluted sports drinks, as these can make diarrhoea worse.
  • Try to have small frequent meals and snacks, and eat slowly.
  • Include a small serving of protein in each meal such as meat, fish, chicken, eggs, tofu, milk, cheese, and yoghurt.
  • Choose foods that are low in fibre such as white rice, pasta, bread, cereals, bananas, mashed potato, boiled green banana, and taro.
  • Avoid foods that may upset your bowel such as wholegrain breads and cereals, dried fruit, nuts and seeds, raw fruit, unpeeled vegetables, spicy, fatty or oily foods, caffeine and alcohol.
  • Try soy or lactose-free milk if you experience a temporary intolerance to milk or dairy products. If your diarrhoea continues, see your treatment team. 

After treatment for bowel cancer

After bowel surgery and treatment, you may need to eat a low fibre diet for four to six weeks. You should only follow this way of eating if instructed by your doctor or dietitian.

Foods to consider avoiding include:

  • seeds, dried fruit and nuts
  • most raw fruit and vegetables
  • grainy breads and cereals
  • tough stringy food such as celery, coconut, and gristle from meat fatty foods such as takeaways and fast foods.


bowel chart


The Cancer Society has a resource called ‘Improving bowel function after treatment’ that gives more guidance. 

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