Has anyone had diarrhea with radiation?

I had 26 radiation treatments to the pelvis generally and 18 prostate-specific, beginning in February and ending in April,2025. I still have daily diarrhea, 8 months afterward. My oncology team and PCP cannot offer a better solution than Imodium, which I take daily. The gastroenterologist who performed my colonoscopy in June did not find irritation or damage at that time, but may be checking again. I am to take 2T Psyllium Husk (fiber) daily as well as a "gut" probiotic, especially one that is designed to stay intact until past the stomach and into the bowel. I can also continue using Imodium. I had a blood test yesterday to rule out Celiac Disease and am to submit stool samples to rule out infection and inflammation. An option would be regular medicated enemas, which neither he nor I prefer. If another solution isn't found, he suggests that I have a Sigmoidoscopy and perhaps biopsy in my future. He used the term "radiation proctitis," which I am hoping if accurate is temporary. Perhaps some of this will be helpful as you speak with your medical team. All the best!

@graybeard46 welcome to the snail club it’s not funny and you have to get use to a different life in some ways I have a good quality pump which doesn’t give me what I need same with the injections , had a good run for many years I’ll miss it till my time is up

I had 44 IMRT treatments during February-April, 2025, 26 to pelvis generally and 18 prostate-specific. Diarrhea began during treatment and continued for eight months until a U Minn online support group recommended Psyllium fiber and Probiotic (Gut Restore, Ancient Nutrition) to take daily. I still have some diarrhea and bowel frequency (3+ BMs daily) with occasional blood spotting. A gastroenterologist diagnosed radiation proctitis in January, 2026. I had four weeks of twice-daily sucralfate enemas, then thirty days of 1000mg Mesalamine suppositories during March-April. Sucralfate stopped the bleeding temporarily and Mesalamine reduced the number (up to 6) of BMs daily. I have the distinct impression that I will be dealing with this for an indeterminate extended period.

Yes , had diarrhea for a month every day during radiation Dr said the same thing , not very helpful

I had SBRT treatment in Nov 2026. Diarrhea started a few days after my last treatment. I contacted my RO who said it should subside within two weeks. He was right. Is it possible that the shorter-duration radiation treatment causes fewer diarrhea symptoms than the 28-day treatment?

@jime51 Your experience sounds very similar to my radiation proctitis. GI stated Imodium works until it doesn't. My bowel lining is in flamed and rectum area had to be cauterized due to rectal bleeding like a period from 9 months post radiation. I am currently doing 3 months of Mesalamine enemas which seems to be helping with the uncontrollable bowel urgency. At two months I am so over them but giving it a try. Also added more fiber such as oats to my diet. I had a sigmoidoscopy and radiation proctitis was confirmed and they cauterized a dozen or so veins. Which probiotic did they recommend? I might give it a try. Thanks.

@chippydoo SBO Probiotics Gut Restore by Ancient Nutrition. The capsule is supposed to stay intact until in the intestines so bacteria survive stomach acid. Your case sounds more severe than mine, but it's not any fun. My symptoms seem to be worsening, so I may be back on Mesalamine after my GI appointment next week.

Jime, Thanks for the probiotic point.

@jime51

This sounds like my story! I used the immodium during the treatment phase but now I use the psyllium---unfortunately, the manufacturers think they make it taste better but it seems like Tang to me!

@texasnole I order "whole Psyllium husks" in bulk online. Now that I'm past treatments of sucralfate enemas and Mesalamine suppositories, my symptoms seem to be returning so I'm back on Psyllium, Probiotic, and Imodium.