Bowel problems after radiotherapy

Radiotherapy for prostate cancer, including external beam radiotherapy, permanent seed brachytherapy and high dose-rate brachytherapy, can sometimes cause bowel problems.

Bowel problems affect each man differently. Some men have mild symptoms, while others have more noticeable symptoms. You may not get all the symptoms described on this page.

Why does radiotherapy cause bowel problems?

Radiotherapy aims to destroy prostate cancer cells. Because the bowel and back passage (rectum) are close to the prostate, healthy tissue can sometimes be affected by the radiation. This can cause inflammation of the lining of the rectum called radiation proctitis. Radiotherapy can also affect the blood vessels, nerves and muscles around the bowel, which may change how your bowel works.

If you already have a bowel condition, such as inflammatory bowel disease (IBD) tell your hospital team before treatment, as radiotherapy may make some bowel problems worse.

What bowel problems can happen?

Symptoms of bowel problems after radiotherapy can include:

• loose and watery bowel movements (diarrhoea)

• passing more wind than usual

• needing to go to the toilet more often, or having to rush to the toilet

• leaking a clear, jelly-like mucus from the back passage

• feeling an urge to have a bowel movement, but then not being able to go

• a feeling that your bowels haven’t emptied properly

• pain in the stomach area (abdomen) or back passage

• bleeding from the back passage – this isn't usually anything to worry about, but let your doctor, nurse or therapeutic radiographer know if it happens

• leaking from your back passage (faecal incontinence)– this is very rare.

Bowel problems can start during radiotherapy and may continue for a few weeks after treatment finishes. For some men, they last longer. Some men don’t develop bowel problems until months or even years after treatment.

If you notice any new changes in your bowel habits later on, speak to your GP or hospital team. You may need further tests to find out what is causing them.

How can bowel problems affect anal sex?

If you’re gay, bisexual or a man who has sex with men, and are the receptive partner (‘bottom’) during anal sex, then bowel problems after radiotherapy may be a particular issue. Read our information for gay and bisexual men.

What can help with bowel problems?

If you are experiencing bowel problems after radiotherapy, there are things you can do yourself that may help. It’s also important to tell your GP, doctor, nurse or therapeutic radiographer about any changes in your bowel habits.

Can changes to my diet help with bowel problems?

Some foods and drinks may make bowel problems such as diarrhoea, wind or bloating worse. Everyone reacts differently to foods during and after radiotherapy. You may need to make small changes to your diet depending on how your bowel reacts. Your doctor, nurse or therapeutic radiographer can advise you if changes are needed.

Some men may find it helps to:

• reduce fizzy drinks

• limit alcohol

• cut down on foods that make them gassy, such as beans, pulses and some green vegetables such as broccoli, cabbage and sprouts

• eat smaller meals more often instead of larger meals

• eat slowly and chew your food well

• drink enough fluids to avoid dehydration

• keep a note of foods and drinks that seem to make your symptoms worse.

Try making any changes to your diet gradually, so you can see what works best for you. Speak to your doctor, nurse or therapeutic radiographer for advice before making any changes to your diet.

Can medicines help with bowel problems?

Some medicines may help manage bowel problems after radiotherapy, such as diarrhoea or needing to rush to the toilet.

Your doctor, nurse or therapeutic radiographer may recommend medicines such as loperamide (Imodium®) to help reduce diarrhoea. Soluble fibre-based medicines and supplements, such as ispaghula husk (Fybogel®) absorb water and may help make loose and watery bowel movements firmer.

Speak to your medical team before trying any medicines or supplements, they will chat through what the best treatment options are based on your symptoms.

What else can help with managing bowel problems?

Living with bowel problems can be distressing, and some men find them difficult or embarrassing to talk about. But support is available, and there are things you can do to help manage your symptoms.

You may find these following tips helpful:

• Plan ahead and find out where the public toilets are before leaving home. You can visit toiletmap.org.uk for a map of public toilets and the accessibility of each location.

• Pack a bag with absorbent pads, underwear and wet wipes if needed.

• Wear clothing that’s easy to remove if you need the toilet quickly.

• Get our Urgent toilet card to show to staff in shops, restaurants and other public places.

• Use a RADAR key if you need access to locked accessible public toilets across the UK.

• Pelvic floor muscle exercises may also help with bowel control. Find out more about pelvic floor muscle exercises.

Where can I get help and support?

If bowel problems are affecting you after radiotherapy, tell your doctor, nurse or therapeutic radiographer. They can review your symptoms and suggest treatments or other ways to help manage them.

Your local continence service may also be able to help. These services are usually run by specialist nurses who support people with bladder and bowel problems. Ask your GP if you can be referred.

If your bowel problems don’t improve, your GP or hospital team may refer you to a bowel specialist. You may need further tests to find out what is causing your symptoms.

Other useful organisations

You can find more information and support from:

• Pelvic Radiation Disease Association (PRDA) who provide information and peer support for people affected by long-term side effects of pelvic radiotherapy.  

• Bladder and Bowel UK who provide information and advice about bladder and bowel problems.

• Macmillan Cancer Support who provide practical, financial and emotional support for people with cancer, their family and friends. 

Dealing with prostate cancer

Being diagnosed and living with prostate cancer can change how you feel about yourself and your life. You may feel scared, overwhelmed, low or even angry. There is no ‘right’ way to feel and everyone reacts differently. It’s important to remember that support is available, and you don’t have to face this alone.

Visit our wellbeing hub for information on looking after your emotional, mental, and physical wellbeing. You can also find out more about our support services and choose what works for you.

If you are close to someone with prostate cancer, find out more about how you can support someone with prostate cancer and where to get more information.

You can also visit our Prostate Health Hub for information and support about living with prostate cancer.

Questions to ask your doctor or nurse

• Is radiotherapy likely to be causing my bowel problems?

• What type of bowel problems might I get? 

• When should I contact my doctor or nurse about my bowel problems?

• Will my bowel problems get better?

• What treatments are available?

• What are the risks and side effects of treatments for bowel problems?

• What can I do to help myself? 

• When should I be referred to a bowel specialist or continence service?

Reviewers and references

Updated: October 2026｜To be reviewed: October 2029

Written by the Prostate Cancer UK Health Information team.

We are committed to reviewing this content within the stated time frame to ensure it is based on the latest published research and maintains clinical accuracy. This is in line with our commitment to the PIF TICK.