Diarrhea is a temporary side effect of some radiation treatments – especially those targeting the abdominal and pelvic region - and many of the drugs used to treat cancer.

Radiotherapy

During Treatment - Nearly half of prostate cancer patients receiving external beam radiation experience diarrhea, abdominal pain and cramping.  Two other groups of radiotherapy patients who have reported these symptoms but in fewer numbers are Hodgkin’s and cervical cancer patients.

Late Occurring - These symptoms are caused by radiation-induced injury to the small intestine.  It may take years to develop, but late radiation injury usually shows up from 8 to 12 months after treatment.

Chemotherapy

In chemotherapy patients, the severity and duration of diarrhea varies with the drug used, the dosing and schedule of administration.  Seventy-five percent of all chemotherapy patients report problems with diarrhea. 

It’s important that steps are taken to deal with this problem.  Dehydration and metabolic imbalances can come on quickly. 

Dietary changes are the first line of defense and attack for diarrhea.

• Eat bland, low-fiber, low-residue foods.

• Reduce the intake of milk products by switching to low-lactose or lactose-free foods.

• Try adding “bulking” agents to your food such as psyllium fiber.  How much to take will depend on the quantity and consistency of stools.  You must also drink lots of water when taking psyllium. 

Your medical team may prescribe anti-diarrheal medications to slow the contractions of your colon and reduce stool frequency. 

• Loperamide HCI slows down the small intestines transit time, increases bile acid absorption thus decreasing the frequency of bowel movements.

• Diphenoxylate hydrochloride with atropine sulfate is effective in reducing colon contractions, reducing cramping and the painful but ineffectual urge to go. 

• And bismuth subsalicylate is used for mild diarrhea.

You may need to drink liquids specially designed to replace potassium and restore the electrolyte balance to your system such as Pedialyte or Gatorade or other sports drinks. Be sure to discuss the use of these over the counter sports drinks with your physician before initiating. 

This page was last edited on 06/19/2003
Written by Rachael Myers Lowe, cancerpage.com
Reviewed by Katie Mullaly, RN, MSN and Jane Quigley, RN, BSN