Radiation Induced Irritable Bowel: What helps?


This is my first post since joining the forum last year.

CONTENT WARNING: My history, from my profile is posted below but if you haven’t started treatment yet you may well not want to read it!

I’m currently 4 months post Chemoradiotherapy treatment . I weaned myself off my morphine and stopped all painkillers 4 weeks ago.

Although I’m happily rid of my opiate induced constipation, I’m now at the other extreme!

My Oncologist reckons this is due to a radiation induced inflammation/ microbiome dysbiosis which causes an Irritable Bowel Syndrome-like pattern of symptoms: colonic spasms, flatulence and frequent, urgent, watery stools.

I’m eating a fairly bland diet based around the BRAT (banana, rice, apple sauce, toast) diet and I’ve cut back on caffeine, alcohol and dairy. Also taking daily pre- and probiotics and kefir but so far, apart from reduced spasms, the diarrhoea is still a problem.

My Oncologist has reassured me that it should gradually get better over the coming 6-12 months.

I’m just wondering if anyone else here has been through this and has anyone found anything particularly useful that got things back on track for them?


This is my story so far…

Started with rectal bleeding in November 2022. Tender lump found by GP on digital rectal examination. December flexible sigmoidoscopy showed lump was high anal and biopsy showed  squamous cell carcinoma (P16 positive- ie caused by HPV) on histology.

Staging scans showed the tumour to be a large-ish locally advanced tumour with local lymph node involvement but no metastases

So my tumour staging was T3 N1 M0

Entered into the Radical Chemoradiotherapy PLATO ACT5 Trial in late February with  IV Mitiomycin on day 1 and oral Capecitabine twice daily on radiotherapy days.

I was randomly allocated to medium intensity radiotherapy arm of the trial (higher than standard intensity but lower than the highest intensity) for 5 and a half weeks.

Needed Morphine to control anal pain 30mg MST am and pm

Usual pattern of side effects with nothing much for the first 2 weeks then anorexia, nausea, constipation cystitis (meaning urgent dash to the loo EVERY 40-50 minutes throughout the day and night), prostatitis (meaning pain and difficulty - needing to strain to pass urine), insomnia, soreness and blistering of peri anal skin, super-screamingly intense tearfulness-inducing pain on opening bowels!

The last 2 weeks of treatment became increasingly nightmarish by the day and the 3 weeks post treatment were almost as bad- I feel a knot of anxiety in my chest as I am writing these traumatic recollections.

Then, as predicted things started to get progressively better!

As of today (late July 2023) I’m 4 months post treatment and just had 3 month scan showing all clear so far.

  • Hello Doctpg

    Welcome to the forum, and to the 'other side'!  I completely get the knot of anxiety writing about it, we get through it and looking back it is like a bad dream.  Even now, I shake my head and think did that really happen to me?

    Yes to the diarrhoea in the early days.  Like you, I stopped the morphine overnight, I became severely constipated and thought the pain was a better alternative.  I had diarrhoea probably for 4 - 5 months and gradually it settled down.  I still have loose stools, but that is by choice, I have a dread of constipation after the early days and take Laxido every day.  But the sprinting to the loo and sometimes not quite making it has long gone.  I still have urgency first thing but controllable (if I don't hang about too long!)  I eat what I want although my appetite isn't what it was once and my taste buds have changed somewhat.

    I am delighted to hear your three months scan was clear and hopefully your bowels will settle down very soon.

    Irene xx

  • Hi Irene

    Thanks for your response. Hmm Thinking I deffo identify with the sprint to the loo and ‘sometimes not quite making it’


    I’ve learned the hard way that, at least for now, I no longer have the luxury of being able to hang around once that initial urge makes itself known!

    It’s reassuring to hear that for you things settled after a few months and that I probably just need to relax and know that my body needs just a bit more time to heal itself.

    I think part of my impatience is about wanting to draw a line under the trauma of it all and to put it behind me. It’s as if the ongoing symptoms are a constant reminder that it still isn’t “all over” yet!

  • Hi Doctpg, congratulations on your NED results which makes the trauma of treatment somewhat worthwhile. I also was on morphine during treatment and around four weeks post treatment then came off it but had to start again due to developing a fissure through constipation. I also took movicol every day but found I was having to go to the loo up to five six times a day. My poor rear end suffered constant cleaning rituals. I was eventually put on a FODMAP diet for three months which for me was great as it cut down bowel movements to one or two a day and possible one around teatime depending on what I had eaten. I am over two years post treatment and cannot eat anything I want to without consequences. I try to follow a healthy diet consisting of the right fibre and the occasional treat. I was doing great after a year but always aware not to get constipated. It’s swings and roundabouts as you don’t want to be loose but paranoid about going the other way and have to strike the right balance. I don’t take laxatives anymore and if I think I haven’t had enough fibre I take a warm glass of water with a teaspoon of blackstrap molasses before bed and that tends to sort me out. I am presently recovering from surgery to remove a lump from my anus so can’t really say I’m fine at the moment but I was doing well living the new normal as I don’t know if you ever return to what it was like before. I am sure some on here do.

  • Hi Jaycee12

    Thanks for sharing your experience. I was thinking about a FODMAP diet but it seemed a bit extreme. It’s good to hear that just a few months on it can help get the bowel back into a more manageable rhythm. And bedtime molasses is a handy hack for constipation that is new to me. 
    Also thanks for the reminder that I may not get to say it’s “all over” and that I maybe need to come to terms with managing a “new normal” for me.

    Sorry to hear that you’ve had to have more medical intervention and I’m wishing you a speedy recovery from your recent surgery.

    All the best!

  • Thank you Doctpg, today I have just received an appointment to attend the Nuclear Medicine Clinic to have a NM Bile acid absorption study. All I know is you swallow a nuclear active capsule and they check what happens. You then return a week later. This is due to the bowel possibly not absorbing nutrients. It’s about a year delayed but better late than never I suppose. 

  • Hi Doctpg and welcome!

    Good for you for getting through the treatment and now to long haul of figuring out just where you fall in the recovery spectrum.

    Going back through my journal, all of my ... er.... bowel miscalculations happened during the first 4 months after treatment. Sometimes I'd get the urge and only have gas, others I'd try to put it off for a few minutes and get caught out. Now, a little over a year out, I still get occasional panics where it comes on and I barely have time to make it to the loo. I can go out and walk and do most things normally, most of the time, but I'm always just a little anxious if there's not a bathroom handy. 

    Eating most of what I want, but there are some foods that trigger the trots and I have to be mindful.

    I take a full dose (9 capsules) of psyllium husk every day, and if I do that and drink a full 40 ounces of water, I'm fine. I get annoyed with myself when I don't, and create problems. 

    Anorexia is a worry on top of all of that. No clue how to manage it. What are you doing to work with it?

    I totally get the knot of anxiety when one goes back in memory to the worst parts. We all come away with some degree of scarring, don't we? Our psyches just as much as our bums.



  • Oh that’s great news- that you’re getting some investigations. I started reading the Macmillan info pamphlet about late radiotherapy bowel complications last night- it was a bit depressing because  it seemed like there’s still a lot that can go wrong even years after finishing treatment Disappointed
    From my understanding of the bile acid absorption thing, it seems like sometimes the small bowel lining is damaged meaning that bile salts (which are normally secreted by the gall bladder to help break down dietary fats) don’t get reabsorbed where they should in the small bowel meaning that they carry on into the large bowel where they shouldn’t be and cause irritation and diarrhoea.

    Maybe this is the cause for your chronic problem. 
    At least if they discover this is what’s going on you’ll be able to get some specific treatment for it.

    Wishing you good luck with the test.

    All the best

  • Morning Doctpg, thank you for that information. If I think about the early post treatment months diarrhoea was really an issue before I did the FODMAP diet. Basically I kept a very simple diet swiSaladhing my favourite vegetables and Salad to green beans and sweet potatoes replaced white potatoes . I cut out all onions, garlic (lots of herb replacements) and various fruits like oranges and peaches and apple with skins were definitely out. I definitely couldn’t eat chocolate, even the dark kind. I made an oat bread to replace ordinary whole meal as I just don’t like white bread. I didn’t eat anything after 6pm to give the gut time to heal and it seemed to work bringing bowel movements to two in the morning. After the three months they told me to start introducing different foods one at a time and keeping a diary but to me it was tiresome and I knew the triggers by then. It was great and I just got used to just turning off the brain when my husband sat with his muffin of some sort in the evening. I would think what goes in has got to come out! Pain is a good deterrent. Before this lump appeared I was in good form and back to walking miles but was never completely like I was before. As Suz said I was always happy knowing if there were toilets here or there JUST IN CASE. I am grateful the hospital is taking me seriously but it’s the delays that are hard which can cause us more frustration. I also say to myself that I’m 68 and have no other health concerns but have been diagnosed with osteoporosis but refuse the drugs and take supplements and go to the gym twice a week with our local cancer charity and yoga at the end of the week. I am it seems the only one there who has had anal cancer and not really able to share much of how it’s affected me but the ladies are great as we have all been through this awful disease. Take care

  • Hi  ,

    Firstly huge congratulations on the fantastic results from your scans!! Amazing news!!

    Your account will ring true with many of us here & like Irene has said recounting it you can definitely feel the rising anxiety. 

    Recovery from this treatment doesn’t always happen in leaps & bounds, it can mean subtle changes over time & all of a sudden you realise that something you’ve been struggling with has improved somewhat. It takes a lot of energy for our bodies to try & heal the damage done by the treatment & rid our systems of the toxicity left behind by both the chemotherapy & radiotherapy so is there any wonder lots of us suffered from fatigue. 

    I completely understand what you’ve said also about the impatience of wanting to put the trauma of the whole situation behind you as I felt exactly the same. 

    If you’re struggling with diet/diarrhoea etc., try keeping a food diary as you may really quickly notice a pattern of certain foods that affect your bowel & digestive system now that never did before. I found some things that affect me post treatment that didn’t affect me before are eggs=constipation, white bread=bloating & constipation, coffee=bloating & awful gas, too much sugary food=bloating & gas, for the most part I’m ok with most everything else now but in the beginning this list was much longer. I’m going out for a curry with my friends this Saturday & really looking forward to it but straight after my treatment had finished I wondered if I’d ever be doing that again as it really wasn’t worth the repercussions if you know what I mean. 

    Hopefully things will continue improving for you. 


  • Hi Suz

    Thanks for your reply. “…figuring out just where I fall in the recovery spectrum” seems like a useful perspective for me right now.

    Although whilst in the throes of my treatment I knew deep down that, after poisoning with chemo and irradiation with X rays, life wouldn’t be a bed of roses, I suppose I just buried my head in the sand and soldiered  on with the business of surviving the torture!

    The responses to my posting here are all helping me to wake up to the realisation that the treatments, although capable of eradicating a malignant tumour, leave in their wake a kind of chronic disorder which needs to be accepted and managed.

    Although a bit depressing, I found the Pelvic Radiation Disease website informative in this respect


    which pointed me back in the direction of the wealth of information on this wonderful Macmillan site



    Thanks for the support through this unwanted but important part of the journey

    All the best