Managing bowel late effects

Many bowel late effects can be managed or treated successfully. Diarrhoea, constipation and wind can be helped by changes to your diet. Anti-diarrhoea medicine can help or fibre supplements for constipation. Pelvic floor exercises can strengthen the bowel and help control problems like urgency and leakage.

Small amounts of bleeding from the bowel may not need treatment. But larger amounts may need treated with heat to seal off the bleeding or drugs given into the bowel. Occasionally oxygen therapy is given to the damaged area to heal damaged blood vessels but this is not available everywhere.

Less common late effects of the bowel include ongoing diarrhoea, and a split in the skin of the anus (fissure). You may need tests to find the cause of ongoing diarrhoea. It can then usually be treated medicine taken by mouth. Anal fissure can usually be treated with creams but some people may need a small operation. Rarer problems caused by pelvic radiotherapy can also be effectively treated.

Talk to your doctor if you are having symptoms. They can give you help and advice and may refer you to a bowel specialist.

Managing late effects

Some people experience some of the following bowel problems after pelvic radiotherapy.

Bleeding from the bowel

Bleeding from the back passage (rectum) after radiotherapy is common, but it’s usually mild and often doesn’t need treatment. Bleeding sometimes improves gradually and can stop on its own after a few years.

Bleeding may not always be a result of previous radiotherapy. It can be caused by piles (haemorrhoids) or straining on the toilet. Or, it could be a sign of cancer in the bowel. But even if you think you know the cause, always tell your cancer doctor or nurse specialist if you have any bleeding from the back passage. It’s important to find out the cause and to rule out serious problems. Your doctor will do an examination of your back passage and may refer you to have a test to look at the inside of your rectum (an endoscopy)


If there is only a small amount of blood and you are finding this manageable, you probably won’t need any treatment. You’ll be given advice about your bowel habits to help minimise the bleeding and avoid constipation. Those taking blood-thinning drugs, may have their dose reduced and monitored.

If you have heavy bleeding that is interfering with your day-to-day life or if you become anaemic (a lack of red blood cells) you’re likely to need treatment. . Your doctor or specialist nurse will explain more about your treatment options and give you more detailed information.

The most commonly used treatment for bleeding from the rectum is a drug called sucralfate (Antepsin Suspension®), given as an enema. An enema is when a fluid (usually medicine) is gently infused into your back passage via a short tube. Sucralfate works by coating the lining of the rectum, reducing inflammation and encouraging healing. It’s important to avoid constipation when you’re being treated with sucralfate.

A drug called formalin is also helpful for some people. It works by sealing the bleeding blood vessels. Your doctor can give it to you using an endoscope which is passed into the bowel. You can have this done under a general anaesthetic.

If bleeding is higher up in the large bowel (colon), or isn’t reduced with enemas, other treatments may be helpful:

Argon plasma coagulation directs heat at areas that are bleeding. The heat seals the blood vessels and destroys damaged tissue. It’s given during a colonoscopy (where a doctor passes a thin flexible tube with a light into your back passage). Doctors don’t yet know how successfully this treats heavy bleeding. There’s also a risk it can cause complications, such as serious tissue damage. Your doctor will discuss this with you.

Hyperbaric oxygen therapy works by increasing the amount of oxygen to tissue that’s been damaged by pelvic radiotherapy. This can encourage new blood vessels to grow and may help tissues heal. Treatment takes up to eight weeks. This treatment isn’t widely available, so you may need to travel some distance for it.

We have more information about hyperbaric oxygen therapy.


Tenesmus is the feeling of needing to go to the toilet often, although your bowel is empty. It can involve straining, pain and cramping. It’s probably due to cramp (spasms) in the muscles that stimulate the bowel, as radiotherapy can affect them. Sometimes tenesmus can be caused by constipation or by cancer. Your doctor will examine your back passage and may arrange for you to have a test, called a flexible sigmoidoscopy, to look at the rectum and lower part of the large bowel.

If tenesmus is caused by radiotherapy changes, the spasms can often be controlled by:

  • pelvic floor exercises
  • soluble fibre to bulk up the stool
  • very low doses of certain antidepressant drugs.


After radiotherapy, some people develop a split in the skin (a fissure) where the back passage opens to the outside of the body (anus). It can cause very sharp, intense pain when you pass a stool (bowel motion). Your doctor will usually prescribe creams that you can apply to the area. It’s important to avoid constipation, as this can make the fissure worse. Your doctor may prescribe a laxative to make it easier for you to go to the toilet.

If the fissure doesn’t improve, it can be treated with injections of botulinium toxin A (Botox®), which are given into the tissue lining the anus. Occasionally some people need a small operation to treat the fissure. This involves making a small cut in the muscle surrounding the anal canal. Releasing the muscle tension allows the fissure to heal. You will usually have a general anaesthetic for this surgery and can have it as a day patient.

Bowel control problems

Feeling that you can’t wait when you get the urge to open your bowels can be stressful, particularly when you’re away from home. You may sometimes have leakage (incontinence). You may just have a small amount that causes some staining on your underwear. But occasionally some people may have an accident and leak a larger amount of stool. Although you might find this difficult to talk about, it’s important to let your doctor know as there is a lot that can be done to help.

What can be done

If you have bowel control problems, such as urgency, leakage, diarrhoea or constipation, there are several things that can help. The best way to manage bowel control problems depends on the symptoms you have and what’s causing them, so it’s important you’re properly assessed. If your symptoms don’t improve, ask your GP to refer you to a gastroenterologist, a specialist nurse or continence adviser for advice.

The most common methods of improving bowel control include:

  • changes to your diet
  • medicines to slow the bowel down
  • strengthening the muscles used for bowel control.


What you eat affects your bowel. For example, fatty or spicy foods, or too much or too little fibre, can stimulate the bowel, making it more difficult to control. Ask your doctor to refer you to a dietitian for expert advice on managing your diet. If you’re losing weight because of bowel problems, it’s important to see a dietitian.

Foods affect people differently, so there may be some trial and error before you work out what’s best for you. Try to find out which foods cause constipation or make your bowel motions loose. You may be able to eat less of them without cutting them out altogether. Caffeine, alcohol and artificial sweeteners can also cause problems.

See our food guide for information about foods that can cause or improve bowel problems.

Some supplements (such as the mineral selenium, which is only needed in small amounts), can cause diarrhoea.


Fibre is important in regulating how your bowel works. There are two types of fibre:

Insoluble fibre helps with managing constipation, but can also help with other bowel problems. It is found in bran, seeds, and multigrain, wholemeal or wholegrain foods, such as bread or cereals.

Soluble fibre helps to bulk up and slow down bowel movements, so may help to reduce diarrhoea or soft stools. It’s found in oats, porridge, bananas, and in apples and pears with their skins removed (the skins contain insoluble fibre). Pulses, such as baked beans and lentils, are also high in soluble fibre, but they stimulate the bowel so aren’t recommended for people with diarrhoea or soft stools.

Your specialist nurse, continence adviser or gastroenterologist (if you’re seeing one) will advise you on the type of fibre you need and how much you should have.

If you’re adding fibre to your diet, do it gradually to give your body time to adjust. Start with small amounts and slowly increase the amount when you’re ready. Make sure you drink more water.

Adding more fibre won’t be right for everyone. After pelvic radiotherapy, you may not be able to cope with as much fibre in your diet as before. So ‘five a day’ won’t always be appropriate. Some high-fibre foods make the bowel produce a lot of gas (wind). You may need to avoid these if wind is a problem for you.

Fibre supplements

Soluble fibre supplements, such as Normacol® or Fybogel (soluble fibre), are often prescribed for people who have frequent bowel motions or incontinence. They’re also used to prevent constipation. They work by absorbing water and expand to fill the bowel, making the stools bulkier and easier to push out. Some people find Fybogel®, can make the bowel produce a lot of gas (wind). You can buy some fibre supplements at the chemist, or your doctor can prescribe them. Always make sure you’re drinking plenty of fluids each day (at least two litres) when you’re taking fibre supplements.

Food intolerance

Sometimes, radiotherapy can affect how well your bowel copes with certain food types, such as:

  • lactose, which is found in dairy products
  • fructose, a fruit sugar sweetener often found in products labelled ‘no added sugar’
  • gluten, a wheat-based protein found in breads, cakes, biscuits and pasta.

Symptoms of food intolerance may include tummy cramps, feeling bloated and increased wind after eating a particular food. If you think you may have a food intolerance, ask your GP to refer you to a gastroenterologist.

Anti-diarrhoea drugs

If changes to your diet aren’t enough to control bowel problems, anti-diarrhoea drugs may help. It’s important to speak to your doctor or specialist nurse before taking any medicines.

The most commonly used treatment is loperamide (also called Imodium® or Diareze®). It slows down your bowel, making the stools more solid and less frequent. Taking loperamide regularly, half an hour before meals, works very well for some people. It’s safe to take it for as long as you need it, but discuss this with your doctor. The dose 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 it’s right for you. Loperamide is also available as syrup, so you can take less and adjust the dose as needed.

Sometimes doctors prescribe other types of anti-diarrhoea tablets, such as codeine phosphate or diphenoxylate (Lomotil). Your doctor or a continence adviser can advise you about the medicines that may be best for you.

Doctors can also prescribe low doses of anti-depressant drugs to help slow down the bowel.

Ongoing diarrhoea

If you have diarrhoea and changes to your diet and anti-diarrhoea drugs don’t help, ask your doctor to refer you to a bowel specialist (a gastroenterologist). A number of things can cause diarrhoea, and a gastroenterologist will be able to do a full assessment.

Radiotherapy can cause other conditions that can lead to ongoing diarrhoea: bile acid malabsorption and small bowel bacterial overgrowth.

Bile acid malabsorption

Bile acids are made in the liver and travel to the small bowel to help us digest fats. They are then absorbed back into our system. Sometimes radiotherapy damages the small bowel so it can’t reabsorb the bile acids (malabsorption). This leads to diarrhoea.

A bowel specialist can diagnose bile acid malabsorption using a scan called a SeHCAT scan. Your doctor can tell you more about this. It’s helpful to have the scan before treatment, to confirm the diagnosis and the extent of its effect on you.

If you have bile acid malabsorption, you’ll need to take a drug for the rest of your life to treat it, and/or stick to a low fat diet. So it’s important to get the diagnosis right.

Bile acid malabsorption can be treated with a drug called colestyramine (Questran®). It comes as a powder that you mix with water or fruit juice.

If your stool is sometimes pale, smelly and difficult to flush away, Questran may not work or may make things worse. If this happens, your specialist may prescribe a newer medicine, called colesevelam (Cholestagel®). You may also be referred to a dietitian for advice on managing a diet that’s lower in fat.

Small bowel bacterial overgrowth

A healthy small bowel contains almost no bacteria. But the large bowel contains lots of healthy or ‘good’ bacteria, which help us digest food. After pelvic radiotherapy, bacteria sometimes grow in places in the small bowel where there shouldn’t be any bacteria. These can cause a number of symptoms, but the most common is diarrhoea. Other symptoms include fatty stool, wind, bloating, constipation, feeling sick, vomiting or bad breath.

You will usually have a breath test to find out if you have small bowel bacterial overgrowth. You can have the test as an outpatient and it takes around 2-4 hours. Your doctor or nurse can explain more about the test.

Small bowel bacterial overgrowth is usually treated with antibiotics.


After radiotherapy, some people have more wind because their pelvic floor muscles are weaker. Although it can be an embarrassing problem, you may be more aware of it than people around you.

The amount of wind we produce is the result of how healthy bacteria and digestive enzymes in our bowel combine with the foods we eat. Some foods, particularly high-fibre foods, such as vegetables and pulses, cause more wind than others.

Too much wind can be caused by:

  • eating certain types of foods - see our food guide
  • constipation
  • some medicines, such as Fybogel and Lactulose
  • bowel conditions (such as diverticular disease)
  • small bowel bacterial overgrowth.

Some tips that may help:

  • Cut down on foods and drinks that can cause wind.
  • Try to have meals at the same times each day, eat more slowly and try not to swallow air.
  • Avoid eating and drinking at the same time.
  • Try doing pelvic floor exercises .
  • Talk to your doctor or specialist nurse about trying laxatives other than lactulose or fybogel which may cause less wind.

Some people find one or more of the following helpful in controlling wind:

  • peppermint oil
  • live yoghurts or probiotic drinks
  • charcoal tablets.

Strengthening the muscles used for bowel control

Exercises to strengthen the muscles used in bowel control can help you manage urgency, leakage and incontinence. They may also help with wind, bowel cramps and tenesmus.

The exercises work the muscles around the back passage (anus) and a deeper layer called the anterior pelvic floor muscles. These muscles also help with bladder control and are used in sex.

Ask your doctor to refer you to a continence adviser to teach you how to do the exercises correctly. You can read more about pelvic floor exercises in our section on bladder changes.

The Bladder and Bowel Foundation also produces a fact sheet with instructions on how to do these exercises. You can order the fact sheet or download the information from their website.

It’s important to:

  • do your pelvic floor exercises correctly, otherwise they won’t work
  • practise regularly to build up your muscles (aim for three times a day)
  • keep to a healthy weight, as being overweight puts extra stress on the pelvic floor muscles.

You need to do your exercises for at least three months to properly strengthen these muscles.

Biofeedback training

Normally our pelvic floor muscles work without us consciously controlling them. As a result, you may find it difficult to know if you’re doing the exercises correctly.

Biofeedback training can help you with your pelvic floor exercises and bowel control. Your continence adviser can advise you on where you can get this training.

Other things you can do

In addition to making changes to your diet, taking medicines to slow your bowel and doing bowel control exercises, there are other things you can do to improve bowel control. Your doctor, specialist nurse or continence adviser can advise you about these.

Some of the following may also help:

  • Keep a diary of your bowel habits to help your specialist work out what might help you.
  • Try to go to the toilet at regular times each day – eating triggers bowel movement for many people, so this may be after meals.
  • If you feel you need to go to the toilet several times a day, practice holding the stool. Over time this will help to increase the amount of stool your bowel can hold.
  • Find ways of reducing stress.
  • If you smoke, try to stop, as smoking stimulates the bowel.
  • If you’re taking other medicines, ask your doctor or nurse if they could be making bowel problems worse – they may be able to prescribe an alternative that affects you less.

Read our section on coping with bladder or bowel changes for advice on skincare, going out and lifestyle changes that may help you cope.

Food guide

The following foods may cause or help bowel problems. This is only a guide, as foods can affect people differently.

Foods that may cause wind include:

  • vegetables such as sprouts, broccoli, cabbage, cauliflower, cucumber, onions, radishes, spinach and sweetcorn
  • baked beans, kidney beans, lentils, chickpeas and other pulses
  • nuts
  • dairy products
  • drinks such as beer and fizzy drinks
  • chewing gum
  • sorbitol (a type of sugar found in some artificial sweeteners, some sugar-free foods and in apples, pears and peaches).

Foods that may help make your stools firmer include:

  • apples and pears (with their skins removed), bananas and potatoes
  • white bread (not a high-fibre variety), white rice (boiled) and pasta (not a wholemeal variety)
  • chicken and fish.

Foods that stimulate the bowel, and make stools softer or more frequent include:

  • some types of fruit (fresh, tinned or dried) – grapes, fruits with stones (such as apricots, plums, peaches and prunes), and most berries (except blueberries)
  • fruit juices, such as prune, orange, apple and grape juices
  • vegetables such as broccoli, sprouts, cabbage, garlic, onions, peas, peppers, spinach and sweetcorn
  • beans, especially baked beans, kidney beans and chickpeas
  • bran and foods high in insoluble fibre
  • greasy foods and fried foods
  • spices such as chilli, curry and ginger
  • caffeine in coffee, tea, chocolate drinks, cola drinks and energy drinks
  • nuts, linseeds and popcorn
  • sugar-free foods containing sorbitol, mannitol or xylitol (such as sugar-free chewing gum, some mints, sweeteners, diet drinks and foods)
  • chocolate
  • alcohol, especially beer and red wine.

These foods should be limited if you have problems with diarrhoea, loose stools or frequent bowel movements. These foods may be helpful if you have constipation.

Greasy and pale stools

Sometimes when bowel motions are loose, they are also paler than usual and much more smelly. The stool may float and be more difficult to flush away, and there may be a film of oil on the toilet water. This is called steatorrhoea.

It can be caused by:

  • small bowel bacterial overgrowth
  • bile acid malabsorption
  • too much fat in the diet
  • a lack of proteins (enzymes) normally made by the pancreas to break down fat.

If you have these symptoms, you need to ask to be referred to a gastroenterologist, who should be able to help you. Steatorrhoea can usually be treated effectively.

Uncommon and rare late effects

Very occasionally, people experience other bowel problems because of pelvic radiotherapy.

Anal stricture

Radiotherapy may cause a tight band of scar tissue to develop at the opening of the back passage. This causes it to narrow (anal stricture). This can cause difficulty and pain when you try to open your bowels. If it’s mild, your doctor will advise you to use a stool-softener laxative or fibre supplement. This will make it easier to go to the toilet, which will help stretch the stricture. If the narrowing is more severe, you may be referred to a bowel specialist. You may be able to have a procedure to stretch the opening (dilatation) or you may have an operation under general anaesthetic to cut through the scar tissue. Your doctor or specialist nurse can explain more about these.

Ulcerated bowel

An area of bowel tissue may break down (ulcerate) and not heal. This can cause watery diarrhoea with blood or mucus in it, and pain and cramping when you go to the toilet. It can be treated with hyperbaric oxygen therapy.

Bowel blockage

A blockage (obstruction) in the bowel can cause sickness (vomiting), pain in the tummy and constipation. You may be given fluids through a drip to rest the bowel and a scan to try and find out what is causing the blockage. If resting the bowel is doesn’t help then some people may need an operation to remove the blockage.

Hole in the bowel wall

Very rarely, a hole may develop in the bowel wall. This is called a perforated bowel. This can make you suddenly unwell and is usually treated straight away with an operation to remove the affected part of the bowel.


This is an opening that forms between two parts of the body. Rarely, an opening can develop between two areas after pelvic radiotherapy. In women this is most common between the back passage and vagina, in men between the urethra and rectum. Sometimes a fistula will close on its own and can be managed with treatment to control symptoms. If this doesn’t happen it may be possible to have an operation to close the opening.

We have more information about fistulas.

Back to Late effects of pelvic radiotherapy

About late effects

Some people may have long term or late effects of pelvic radiotherapy. These can usually be treated or managed successfully.

Bladder changes

Late effects on the bladder can usually be managed or treated successfully. Talk to your doctor about any symptoms.

Bowel changes

Late bowel effects of pelvic radiotherapy are usually managed or treated successfully. Talk to your doctor if you notice any symptoms.

Late effects and sex life

Pelvic radiotherapy can have some late effects on your sex life. Talk to your doctor for advice on how to manage these.