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Managing Cancer Care


Diarrhea is the passage of loose or watery stools several times a day with or without discomfort. It can happen when water in the bowel (colon or intestine) isn’t being absorbed back into the body for some reason.

There are many conditions and medications that can cause diarrhea, some that are related to cancer and some that are due to other health problems. Common causes can include chemotherapy, targeted therapy, or immunotherapy treatments, radiation therapy to the pelvic area, and certain medicines. Sometimes there are certain types and locations of tumors that might cause diarrhea.

Diarrhea can also be caused by things you eat that may not agree with you, such as sugary, spicy, fatty, or fried foods. Other problems that can cause diarrhea are infection, surgery, or liquid food supplements that are concentrated with vitamins, minerals, sugar, and electrolytes.

Sometimes diarrhea can be caused by an overflow of intestinal liquids around something that’s partly blocking the intestine, such as hard stool or part of a tumor. If hard stool is blocking the intestine, this is called an impaction.

Depending on the type of treatment being given, diarrhea can start within hours, days, or weeks after receiving chemotherapy, targeted therapy, or immunotherapy. Radiation therapy can also cause diarrhea over a period of time. Sometimes treatment-related diarrhea can last up to several weeks or months after treatment ends.

After stomach or bowel surgery, some people may have diarrhea. This might be because parts of the digestive system were removed during surgery, such as part of the intestine or stomach. Or, it might be because the surgery has caused sensitivity to sweet or high-carbohydrate foods. In these cases, diarrhea can be a long-lasting problem. It's a good idea to avoid gassy foods and carbonated drinks. It's also important to sip fluids during the day to prevent dehydration.

A weakened immune system due to cancer treatment can cause a higher risk for an infection which may cause diarrhea, too.

Diarrhea that's not treated or managed well can lead to dehydration and malnutrition.

What the patient can do

Ask the cancer care team if diarrhea can be expected after surgery or after getting any type of cancer treatment or new medication. Depending on the cause of diarrhea, some of these tips might be helpful for people with cancer.

  • Try a clear liquid diet (one that includes water, weak tea, apple juice, peach or apricot nectar, clear broth, popsicles, and gelatin with no solids added) when diarrhea starts or when you feel that it’s going to start. Avoid acidic drinks, such as tomato juice, citrus juices, and fizzy soft drinks.
  • Take medicine for diarrhea only if and as prescribed.
  • Track the amount and frequency of bowel movements.
  • Include foods that are high in potassium (such as bananas, potatoes, apricots, and sports drinks like Gatorade® or Powerade®). Potassium is an important mineral that you may lose if you have diarrhea.
  • Drink and eat high-sodium (salt) foods like broths, soups, sports drinks, crackers, and pretzels.
  • Drink at least 1 cup of liquid after each loose bowel movement. Keep liquids caffeine-free. Try water, sports drinks, or bouillon.
  • As diarrhea improves, try eating small amounts of foods that are easy to digest such as rice, bananas, applesauce, yogurt, mashed potatoes, low-fat cottage cheese, and dry toast.
  • If diarrhea keeps getting better after a day or 2, start small regular meals.
  • Use dampened toilet paper or baby wipes to clean yourself to help soothe the anal area.
  • Sitting in a tub of warm water or a sitz bath may help reduce anal discomfort.
  • Applying a water-repellent ointment, such as A&D Ointment® or petroleum jelly, to the anal area may also help.
  • Avoid milk or milk products if they seem to make diarrhea worse. Yogurt and buttermilk are usually OK.
  • Avoid pastries, candies, rich desserts, jellies, and preserves.
  • Avoid high-fat foods, like fried and greasy foods because they also can make diarrhea worse.
  • Don’t drink alcohol or use tobacco.
  • Avoid high-fiber foods, which might make diarrhea worse. These include nuts, seeds, whole grains, legumes (beans and peas), dried fruits, and raw fruits and vegetables.
  • Do not chew sugar-free gum or eat candies and desserts made with sugar alcohol (i.e., sorbitol, mannitol, or xylitol).

What caregivers can do

  • See that the patient drinks about 3 quarts of fluids each day.
  • Ask the cancer care team how much or how long diarrhea should last before calling to report it.
  • Keep a record of bowel movements to help decide when the cancer care team should be called.
  • Ask before using any over-the-counter diarrhea medicine.
  • Check the anal area for red, scaly, broken skin.
  • Protect the bed and chairs from being soiled by putting pads with plastic backing under the patient.
  • Encourage room temperature drinks. They might be better tolerated than cold or hot drinks

Call the cancer care team if the patient

  • Has loose bowel movements several times a day or for 1 to 4 days, depending on instructions given when treatment starts 
  • Has blood in the stool or around anal area
  • Has a fever of a certain level when taken by mouth, as instructed when treatment starts.
  • Has new belly pain or cramps or a swollen belly
  • Does not urinate for 12 hours or more
  • Does not drink liquids for 24 hours or more
  • Has been constipated for several days and then begins to have small amounts of diarrhea or oozing of liquid stool.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Abraham, JL.  A Physician's Guide to Pain and Symptom Management in Cancer Patients. 3rd ed.  Baltimore, MD: John Hopkins University Press;2014:449.

Cherny NI, Werman B. Diarrhea and constipation. In DeVita VT, Lawrence TS, Rosenberg SA, eds. DeVita, Hellman, and Rosenberg’s Cancer: Principles and Practice of Oncology. 11th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2019:2086-2094.

National Comprehensive Cancer Network. Palliative care: Diarrhea. Version 2.2019. Accessed at on September 17, 2019.

Thorpe DM, Byar KL. Bowel Dysfunction. In Brown CG, ed. A Guide to Oncology Symptom Management. 2nd ed. Pittsburgh, PA: Oncology Nursing Society; 2015:77-118.

Last Revised: February 1, 2020

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