Managing bowel late effects

Treatment for bowel cancer or pelvic radiotherapy for other cancers can cause long-term changes to the way the bowel works. There are lots of ways of managing or treating bowel symptoms.

Bowel control after treatment

If you have a bowel control problem, you may have:

  • difficulty controlling when and how often you pass stools (poo) or wind
  • problems controlling your bowel, leading to leakage or soiling, cramps, or bloating
  • diarrhoea or constipation
  • difficulty emptying your bowel completely.

Not feeling in control of your bowel can be stressful, particularly when you are away from home. Although you might find it difficult to talk about bowel control problems, it is important to tell your doctor or specialist nurse. There are many things that they can do to help.

Bowel problems may be caused as a late effect from pelvic radiotherapy, or as a result of late effects of bowel cancer treatment.

Improving bowel control

Your doctor or nurse will probably have helpful suggestions. The most common ways of improving bowel control include:

  • changes to your diet
  • drugs to regulate your bowel
  • exercising and strengthening the muscles used for bowel control.

If your symptoms do not improve, you can ask your GP to refer you to a continence advisor, or a doctor who treats problems with the digestive system (gastroenterologist).

Tests to check for bowel problems

Your doctor or nurse will usually ask about your bowel problems and things that affect your symptoms. It is important that they properly assess your situation. The right treatments for bowel control problems depend on your symptoms and what is causing them.

You may have some of the following tests:

  • blood and stool tests – you may have a sample of blood taken to be tested in a laboratory. You may also be asked to collect a sample of your poo (stool)
  • x-rays and scans – x-rays and scans can be used to look inside your body.
  • camera (endoscopy) tests such as a colonoscopy or sigmoidoscopy – this is where a doctor or nurse passes a scope (a thin tube with a light and tiny camera on the end) into the bowel to look for any abnormal areas
  • breath tests – this is where a doctor uses samples of your breath to investigate symptoms such as diarrhoea or discomfort in your tummy (abdomen).

Diet and bowel problems


It is important to try to eat at regular times. This helps to encourage a regular bowel pattern. Skipping meals may make your symptoms worse.

You may notice certain foods make your stools loose or increase wind. You may want to try eating less of these foods, without cutting them out altogether. It is best to do this with the support of a dietitian. This is because it is important to continue to eat a wide range of different food types.

Your doctor can refer you to a dietitian for expert advice on managing your diet. The dietitian may ask you to keep a food and symptom diary. It lets them see the types of food you usually eat and what changes may help your symptoms.

Download our food and symptom diary [PDF]


Try to drink at least 1 to 2 litres (2 to 3½ pints) of fluids a day, unless your healthcare team tell you differently. Water is best. Drink smaller amounts through the day so that you do not drink lots of fluids with meals. Some types of drinks can make bowel problems worse. You may want to limit drinking:

  • fizzy drinks
  • caffeinated drinks (like coffee, tea or cola)
  • alcohol
  • sugar-free drinks that contain artificial sweeteners.


Changing the amount of fibre in your diet may help with bowel problems. Your doctor, nurse or dietitian will give you advice about the type of fibre you need and how much you should have. This depends on the treatment you had and the type of bowel problem.

There are 2 types of fibre:

  • Insoluble fibre helps with managing constipation. It can also help with other bowel problems. You can get insoluble fibre from wholegrain bread and cereals, vegetables and fruit skins. It is also in bran and seeds.
  • Soluble fibre helps bulk up and slow down bowel movements, so it may help improve diarrhoea or soft stools. You can get soluble fibre from oats and bananas, and from apples and pears with their skins removed. It is important to remove the skins, because they contain insoluble fibre.

If you are adding fibre to your diet, do it slowly. This gives your body time to adjust. Start with small amounts and slowly increase the amount when you are ready. Fibre absorbs fluid, so make sure you also drink more water. This helps the stool stay soft and move through the bowel easily.

Adding more fibre is not right for everyone. Following the 5-a-day plan for fruit and vegetables may not always be appropriate either. Your doctor, nurse or dietitian may give you advice about blending, slow cooking and peeling fruit and vegetables to reduce the amount of fibre you have.

Soluble fibre supplements

People with bowel control problems are often prescribed soluble fibre supplements, such as Normacol® or Fybogel®. They work by absorbing water and expanding to fill the bowel. This makes the stools bulkier and easier to push out. But some people find Fybogel® makes the bowel produce more wind.

If you are taking fibre supplements, make sure you drink plenty of fluids. You should drink at least 2 litres (3½ pints) of fluids every day.

Food intolerance

Sometimes radiotherapy can affect how well your bowel copes with certain food types, such as lactose or fructose. Lactose is found in milk and some other dairy products. Fructose is found in sugar and fruit.

Symptoms of food intolerance may include:

  • tummy cramps
  • feeling bloated
  • having more wind after eating a particular food.

If you think you may have a food intolerance, ask your GP to refer you to a gastroenterologist.

Food intolerance may improve over time, so it is worth trying foods again rather than avoiding them for long periods of time.

Drugs and diarrhoea

Anti-diarrhoea drugs

If you have urgency, loose stools, diarrhoea or bowel incontinence, anti-diarrhoea drugs may help. It is important to speak to a doctor or specialist nurse before taking any medicines.

The most commonly used treatment is loperamide. It slows down your bowel, making the stools more solid and less frequent. Taking loperamide regularly can work very well for some people. It usually works best when taken about 20 to 30 minutes before eating a meal.

It is safe to take loperamide for as long as you need it. But you should discuss this with your doctor.

The dose of loperamide you take may need to be adjusted until you find what works best for you. Your doctor may recommend starting with a low dose and increasing this until your symptoms are controlled. Loperamide is available as a syrup, which allows you to make small changes to the dose as needed.

Sometimes loperamide can cause cramps. If this happens, taking a lower dose may help.

There are other types of anti-diarrhoea medicine, such as codeine phosphate or diphenoxylate (Lomotil®). Your doctor or a continence adviser can give you advice.

Drugs that can increase bowel symptoms

You may be taking medicines that can make bowel symptoms worse. For example:

  • magnesium in antacids – this treatment for heartburn may cause diarrhoea
  • proton pump inhibitors such as omeprazole (Losec®) may cause wind and diarrhoea
  • laxatives such as Lactulose® and Fybogel® may cause wind and diarrhoea
  • metoclopramide – this anti-sickness drug may cause diarrhoea
  • metformin – this tablet to treat diabetes may cause diarrhoea, particularly when you have just started taking it
  • beta-blockers – these tablets to treat high blood pressure and some heart problems may cause diarrhoea.

If you think a drug you are taking might be making your symptoms worse, tell your doctor. They may be able to prescribe a different drug that may affect you less.

Drugs and constipation

Drugs to treat constipation

If you have problems with constipation or difficulty emptying your bowel completely, you may be given one of the following treatments:

  • Soluble fibre supplements – these include Fybogel® or Normacol®.
  • Suppositories – you put these into your back passage or stoma. As they dissolve, they release a lubricant. This encourages the bowel to empty. They usually take about 10 to 30 minutes to work. It may be easier to use them at a time when you are able to stay near a toilet for a while after inserting them. You may not need to use them every day. Ask your doctor or nurse if you want to try using them at night so they have longer to work.
  • Enemas – these contain a small amount of gel or liquid that you squeeze into the lower bowel. This stimulates the bowel to empty.

Drugs that can cause constipation

Your doctor can check whether you are taking any drugs that can cause constipation. They may be able to prescribe a different drug.

Medicines that may cause constipation include:

  • opioid painkillers, such as codeine or morphine
  • ondansetron, which is an anti-sickness drug
  • iron tablets
  • loperamide or other anti-diarrhoea drugs.

Smoking and vaping

If you have problems with urgency, loose stools or bowel incontinence, smoking or vaping may make things worse. This is because nicotine stimulates the bowel. Talk to your doctor about ways to stop smoking or smoke less. We have more information about quitting smoking.

Exercises for bowel control

Exercises to strengthen the muscles used in bowel control are called pelvic floor exercises. These are sometimes called Kegel exercises. They may help with:

To avoid putting extra pressure on your pelvic floor muscles, try to keep your weight within healthy limits. You can also look after these muscles by avoiding getting constipated and not doing heavy lifting.

Bowel retraining

Some bowel control problems can make it difficult to predict when you will need a toilet. This can be very stressful. You may worry that you will not be able to ‘hold on’. Or you may be checking all the time for signs that you need to go.

A continence advisor may suggest a bowel retraining programme to help you feel more in control. This teaches you ways to:

  • resist the urge to go straight away
  • get your bowel habits into a regular, predictable pattern
  • manage any anxiety you have about bowel control.

Bowel retraining may also involve other methods such as anti-diarrhoea medicines (see above) and pelvic floor exercises.

Good toilet habits for bowel control

If you have ongoing problems with constipation or difficulty emptying your bowel, good toilet habits can help.

Toilet routine

Most people find the best time to empty their bowel is about 30 minutes after a meal. But this can vary. You may already know what time works best for you. It is important not to push hard to try to pass a stool (poo). This can weaken your pelvic floor muscles and may cause problems with bowel control in the future.

If you have to wait for a long time on the toilet, you may be going to the toilet too soon. Or it may be a sign that you are constipated. Try not to go to the toilet until you have a strong urge to pass a stool. And try not to sit on the toilet for more than 20 minutes.

Toilet posture

Sitting in the right position on the toilet can help you to empty your bowels. Lean forward a little and rest your elbows on your knees. Use a small footstool to raise your feet off the floor by about 20cm (8 inches). This will make your knees higher than your hips. Do not strain or hold your breath. Straining or holding your breath makes the muscles tighten, instead of relaxing them so you can pass stool. You may find using a relaxed breathing technique helps.


The correct position for emptying your bowels
Image: The correct position for emptying your bowels


If you have had recent hip surgery, do not use this position. Always check with your doctor first.

About our information

  • References

    Below is a sample of the sources used in our pelvic radiotherapy information. If you would like more information about the sources we use, please contact us at

    Andreyev HJN, Muls AC, Norton C, et al. Guidance: The practical management of the gastrointestinal symptoms of pelvic radiation disease. Frontline Gastroenterology, 2015; 6, 53-72.

    Dilalla V, Chaput G, Williams T and Sultanem K. Radiotherapy side effects: integrating a survivorship clinical lens to better serve patients. Current Oncology, 2020; 27, 2, 107-112.

    The Royal College of Radiologists. Radiotherapy dose fractionation. Third edition. 2019. Available from: [accessed March 2021]. 

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Chief Medical Editor, Professor Tim Iveson, Consultant Medical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

Date reviewed

Reviewed: 31 July 2021
Next review: 31 July 2024
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

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