Managing bowel late effects

Many bowel late effects can be managed or treated successfully.

Medicines can help to control diarrhoea and constipation. Pelvic floor exercises can strengthen the bowel and help control problems like urgency and leakage.

Small amounts of bleeding from the bowel are common and may not need treatment. But larger amounts may need to be treated using drugs given into the back passage. Other treatments are available if drug treatments don’t work.

Less common late effects of the bowel include a split in the skin of the anus (fissure) or a narrowing of the opening of the back passage (stricture). An anal fissure can usually be treated with creams but some people may need a small operation. A stricture can often be managed with stool softeners, but may need a small operation. Other 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.

Late effects of pelvic radiotherapy on the bowel

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 is 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 caused by the radiotherapy. It can be caused by piles (haemorrhoids) or straining on the toilet. 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 is 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 it manageable, you probably won’t need any treatment. You will be given advice about your bowel habits to help minimise the bleeding and avoid constipation. If you are taking blood-thinning drugs, your dose may be reduced and monitored.

If you have heavy bleeding that is interfering with your day-to-day life or if you become anaemic (have a lack of red blood cells), you are 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 back passage is a drug called sucralfate (Antepsin Suspension®). It is given as an enema. This is when a fluid (usually medicine) is gently infused into your back passage through a short tube. Sucralfate works by coating the lining of the rectum. This reduces inflammation and encourages healing. It is important to avoid getting constipated when you are 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 the bleeding is higher up in the large bowel (colon), or if enemas don’t reduce the bleeding, 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 is also a risk that 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 that gets to tissue that’s been damaged by pelvic radiotherapy. This can encourage new blood vessels to grow and may help the tissue heal. Treatment takes up to eight weeks. This treatment isn’t widely available, so you may need to travel some distance for it.


Tenesmus is the feeling that you need to go to the toilet although your bowel is empty. It can involve straining, pain and cramping. It can be caused by cramp (spasms) in the muscles that stimulate the bowel.

The spasms can often be controlled by:

  • pelvic floor exercises
  • taking soluble fibre to bulk up the stool
  • very low doses of certain anti-depressant drugs.

Sometimes tenesmus can be caused by constipation. It’s also sometimes caused by a non-cancerous growth (a polyp) in the bowel, or it can be caused by a cancer.

If you have tenesmus, your doctor will examine your back passage and may arrange for you to have a test called a flexible sigmoidoscopy. This looks at the rectum and the lower part of the large bowel.


After radiotherapy, some people develop a split in the skin of the anus. This is called a fissure. It can cause a sharp, intense pain when you pass a stool (bowel motion).

Your doctor can usually prescribe creams to apply to the area that will help. It’s important to avoid getting constipated, because this can make a fissure worse. Your doctor may also prescribe a laxative to make it easier for you to go to the toilet.

If the fissure doesn’t get better, your doctor may advise treating it with injections of botulinum toxin A (Botox). These are given into the tissue lining the anus.

Some people may need a minor operation to make a small cut in the muscle surrounding the anus. This releases the tension in the muscle and allows the fissure to heal. You usually have this operation under a general anaesthetic, and it can be done as a day patient.

Bowel control problems

After radiotherapy, some people feel that they can’t wait when they get the urge to open their bowels. This can be stressful, particularly when you’re away from home. You may sometimes have leakage (incontinence). The amount of incontinence varies. You may just have a small amount that causes some staining on your underwear. But occasionally you 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 a lot of things can 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 to be 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 ways of improving bowel control include:

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

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 (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, which allows you to take less and adjust the dose as needed.

Sometimes doctors prescribe other types of anti-diarrhoea tablet, 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 changes to your diet and anti-diarrhoea drugs don’t help your diarrhoea, 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. These conditions include:

  • bile acid malabsorption
  • 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. This is called malabsorption. It leads to diarrhoea.

A bowel specialist can diagnose bile acid malabsorption using a scan called a SeHCAT scan. Your specialist can tell you more about this. The scan will confirm whether you have bile acid malabsorption and also tell you how much will affect you. It is important to get the diagnosis right. This is because if you have bile acid malabsorption, you will need to take a drug for the rest of your life to treat it. You may also be advised to keep to a low-fat diet. 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 bowel movements (stools) are sometimes pale, smelly and difficult to flush away, Questran may not work. Or it may make things worse. If this happens, your specialist may prescribe a newer medicine, called colesevelam (Cholestagel®). They may also refer you to a dietitian for advice on keeping to a low-fat diet.

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. This can cause a number of symptoms, but the most common one is diarrhoea. Other symptoms include fatty bowel movements (stools), wind, bloating, constipation, feeling sick, vomiting and bad breath.

You will usually have a breath test to find out whether 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 the people around you.

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

Too much wind can be caused by:

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

If you have too much wind, these tips 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 and Fybogel, which may cause less wind.
  • Some people find peppermint oil, live yoghurts, probiotic drinks or charcoal tablets helpful in controlling wind.

Strengthening the muscles used for bowel control

You can do exercises to strengthen the muscles used in bowel control. These exercises can help you manage urgency, leakage and incontinence. Some people find they also help with wind, bowel cramps and tenesmus.

The exercises work the muscles around the anus. They also work a deeper layer of muscles, 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.

It is 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, because 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. Because of this, you may find it hard to know whether 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 yourself

As well as 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. Many people need to go to the toilet after eating, so your regular time might be after meals.
  • If you feel you need to go to the toilet several times a day, practise holding the stool. Over time this will help 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 whether they could be making bowel problems worse. If so, they may be able to prescribe an alternative that affects you less.

We have more information about skincare, going out and lifestyle changes that may help you cope with bowel problems.


Some people notice that when their bowel motions (stools) are loose, they are also paler than usual and much more smelly. The stool may float in the toilet and be harder to flush away. There may also 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 your GP to refer you to a gastroenterologist, who should be able to help you. Steatorrhoea can usually be treated effectively.

Uncommon and rare late effects

Very occasionally, people may have the following bowel problems because of pelvic radiotherapy.

Anal stricture

Radiotherapy may cause a tight band of scar tissue at the opening of the back passage (anus). This causes it to narrow. It is called an 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 take a stool-softening 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, your doctor may refer you to a bowel specialist. You may be able to have a procedure to stretch the opening.This is called 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 treatments.

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. It can also cause pain and cramping when you go to the toilet.

This 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. You may also be given treatment for constipation. 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. It can make you suddenly unwell.

This is usually treated straightaway with an operation to remove the affected part of the bowel.


A fistula is an opening that forms between two parts of the body. After pelvic radiotherapy, an opening can develop between the rectum and urethra, although this is rare. It is more likely to happen in men who’ve had brachytherapy for prostate cancer after a biopsy (removing a tissue sample) of the rectum.

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

Pelvic radiotherapy can damage the bladder and the muscles around it. This can change how the bladder functions.

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. Your doctor or nurse can give you advice on how to manage these.