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Diarrhea: Cancer Treatment Side Effect

A woman is drinking a full bottle full of water to stay hydrated

Drink plenty of fluids to prevent dehydration. It may also help to avoid certain foods, such as dairy products. Talk with your doctor to learn what medicine to take.

Credit: iStock

What is diarrhea?

Diarrhea means having bowel movements that are soft, loose, or watery more often than normal. If diarrhea is severe or lasts a long time, the body does not absorb enough water and nutrients. This can cause you to become dehydrated or malnourished.

What causes diarrhea?

Cancer treatments, or the cancer itself, may cause diarrhea or make it worse. Some medicines, infections, and stress can also cause diarrhea. Tell your health care team if you have diarrhea.

What are the dangers of diarrhea?

Diarrhea that leads to dehydration (the loss of too much fluid from the body) and low levels of salt and potassium (important minerals needed by the body) can be life threatening. Call your health care team if you feel dizzy or lightheaded, have dark yellow urine or are not urinating, or have a fever of 100.5 °F (38 °C) or higher.

Ways to manage diarrhea

You may be advised to take steps to prevent complications from diarrhea:

  • Drink plenty of fluid each day. Most people need to drink 8 to 12 cups of fluid each day. Ask your doctor or nurse how much fluid you should drink each day. For severe diarrhea, only clear liquids or IV (intravenous) fluids may be advised for a short period.
  • Eat small meals that are easy on your stomach. Eat six to eight small meals throughout the day, instead of three large meals. Foods high in potassium and sodium (minerals you lose when you have diarrhea) are good food choices, for most people. Limit or avoid foods and drinks that can make your diarrhea worse.
  • Check before taking medicine. Check with your doctor or nurse before taking medicine for diarrhea. Your doctor will prescribe the correct medicine for you.
  • Keep your anal area clean and dry. Try using warm water and wipes to stay clean. It may help to take warm, shallow baths. These are called sitz baths.

Questions to ask your health care team about diarrhea

Prepare for your visit by making a list of questions to ask. Consider adding these questions to your list:

  • What is causing the diarrhea?
  • What symptoms should I call you about?
  • How much liquid should I drink each day?
  • Can I speak to a registered dietitian to learn more about foods and drinks that are best for me?
  • What medicine or other steps can I take to prevent diarrhea and to decrease rectal pain?

NCI's Gastrointestinal Complications PDQ® summary discusses GI problems common in cancer patients. For more information, see the section on diarrhea in the patient or health professional version.

Listen to tips on how to manage diarrhea caused by your cancer treatments such as radiation therapy.
(Type: MP3 | Time: 2:55 | Size: 2.7MB)

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