How will radiation therapy affect my bowel function and bowel movements?

The lining of the bowel is very sensitive to radiation and may become inflamed, or swollen (a condition called enteritis) during treatments. Radiation may also cause an inflammation of the stomach (called gastritis) or an inflammation of both the stomach and the bowel (called gastroenteritis). Your treatments may cause you to have:

  • Abdominal bloating or cramps.
  • Thin or loose stools.
  • Watery diarrhea.
  • Sense of urgency to have a bowel movement.

The symptoms above may occur during the second or third week of radiation therapy. Occasionally, blood or mucus may appear in the stool.

What should I do if I have these bowel symptoms?

If you have these symptoms, it is a good idea to:

  • Tell your nurse or doctor if you have diarrhea more than two or three times a day or if you notice mucus or blood when you have a bowel movement. Your healthcare provider may prescribe medication for you.
  • Drink at least six 8-ounce glasses of fluids a day. (Choose pulpless fruit juices, broths or flat sodas).
  • Drink liquids between meals instead of drinking liquids with your meals.
  • Be sure to tell your healthcare provider if you think you need an anti-diarrheal medication. You may be instructed to take an over-the-counter anti-diarrheal medication after each bowel movement to control mild diarrhea. (Please note: Be sure to follow the directions on the medication -- you should not take more than eight tablets per day).
  • Avoid eating fiber-rich foods such as bran, nuts and whole grain cereals or breads.
  • Eat cooked, peeled or canned fruits and vegetables. Avoid fruits or vegetables with skins or seeds such as berries and grapes. Avoid cabbage, broccoli, corn and peas, as these vegetables cause you to have gas.
  • Eat small, frequent meals instead of three large meals. Prepare warm food rather than very hot or very cold food.
  • Avoid eating spicy foods or foods that are high in fat.

What can I do to relieve discomfort in the rectal area?

If your rectal area becomes sore because of frequent bowel movements, or if you have itching, burning, or pain during bowel movements, try warm sitz baths (sit in a few inches of warm water in a bathtub). You may be instructed to add epsom salts or another type of tablet to the water. After cleansing, pat the area dry (do not rub) with a clean, soft towel.

Can diarrhea be harmful to my health?

Continuous diarrhea causes the body to lose large amounts of water and nutrients. If you have diarrhea more than three times a day and you are not drinking enough fluids, you could become dehydrated. Dehydration is the loss of water from body tissues and it disturbs the balance of essential substances in your body. Dehydration can cause serious complications if it is not treated.

Tell your healthcare provider if you have persistent diarrhea and are experiencing any of these signs of dehydration:

If I have symptoms of diarrhea, how long will they last?

You may continue to have diarrhea for several weeks after your radiation treatment is complete. After your treatment is over, continue to use medication as directed by your healthcare provider and avoid dietary fibers. You can return to your normal diet once your bowel function is back to normal.


© Copyright 1995-2016 The Cleveland Clinic Foundation. All rights reserved.

This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 6/17/2016...#4531