Cancer patients may have loosened bowels as a side effect of cancer treatments and medicines. Having three or more loose or watery stools in a day is known as diarrhea. Uncontrolled diarrhea can cause your body to become dehydrated (loss of fluids). You might also feel weak, lose your appetite, and lose weight.

There are many causes for diarrhea among people with cancer, including treatment, infections, and stress.

Dealing with Diarrhea

You can deal with diarrhea by understanding its causes and learning tips to prevent and treat it.

Causes of Diarrhea

Cancer treatments and medicines can cause diarrhea. Other common causes of diarrhea include infection and surgery.

Manage Diarrhea

If you have diarrhea, here are some things you can do to keep enough fluid in your body (hydration) and help you feel better.

  • Drink clear fluids to prevent dehydration.
  • Avoid alcohol and caffeine.
  • Avoid acidic foods or liquids including citrus, tomatoes, and sodas.
  • Eat small meals and snacks every 2 or 3 hours.
  • Avoid foods that are fried, greasy, spicy, or very sweet.
  • Avoid or limit milk and dairy products if they make diarrhea worse.
  • Sip soups made with vegetables like potatoes, carrots, zucchini, and mushrooms.
  • Try popsicles, sherbet, and gelatin for desserts.
  • If diarrhea is related to chemotherapy, your cancer care team may recommend a special diet, adjust your chemotherapy schedule or plan, or prescribe a medicine to help prevent or lessen diarrhea symptoms.
  • Check with your doctor to see if your diarrhea is due to infection or another causes that can be treated.
  • Once your diarrhea has stopped, slowly start eating foods with fiber.

Listen to Tips on Managing Diarrhea

This recording gives you some tips on how to deal with diarrhea caused by radiation therapy.

Manage Dehydration

Diarrhea can cause dehydration, which means not having enough fluid in your body. Your body needs to have a certain amount of fluid, and not having enough can lead to serious health problems. Look for signs of dehydration. Learn more.

Know the Signs

  • Dry mouth and lips
  • Thirst
  • Constipation, dizziness, fatigue, and feeling faint
  • Food sticking in the base of your throat when you start to swallow
  • Difficulty speaking due to a dry, sticky mouth
  • Dry skin that “tents” (stays up) when lightly pinched
  • Dark urine that is less than usual

Manage the Symptoms

  • Drink clear liquids. In some cases, fluids may need to be given by IV (intravenously/in a vein).
  • Suck on ice chips to relieve dry mouth.
  • Fill a small cooler with juice boxes, bottled water, or other drinks and keep it nearby.
  • Use lip balm to avoid painful cracking.
  • Use lotion to soften your dry skin.
  • Try to get rid of what can worsen dehydration, such as vomiting, diarrhea, or fever.

Get Support

For more detailed information on support options, visit Get Support.

Talk to Your Health Care Team

Your health care team needs to know how you’re doing. Be sure to tell them about any changes you notice.

Talk to Family and Friends

Your loved ones want to support you. They can help with activities like housework, running errands, and getting to appointments. Be as specific as possible about the kind of help you need.

Find Peer Support

Talk About Your Concerns

Peer groups offer a welcoming environment to share your feelings and experiences with people who are going through the same things. Use the American Cancer Society’s Resource Search to find a peer group in your area or call the American Cancer Society at 1-800-227-2345 for personalized assistance.

Visit the Cancer Survivors Network Online

The Cancer Survivors Network is an online community with more than 40 discussion boards where cancer survivors share their cancer-related experiences, support one another, and exchange practical tips.

NCI Cancer Information Service


Speak to a National Cancer Institute health information specialist by calling 1-800-4-Cancer.


The National Cancer Institute offers live, online assistance through its LiveHelp service.

ACS National Cancer Information Center

Get Tips

Get information and tips from a cancer information specialist at the American Cancer Society by calling 1-800-227-2345. Lines are open 24 hours a day, 7 days a week.


The American Cancer Society offers live, online assistance 24 hours a day, 7 days a week. Select the Live Chat option from any page on cancer.org.

Learn More About Diarrhea

The National Cancer Institute and the American Cancer Society have additional resources to help you, including:

The American Cancer Society book What to Eat During Cancer Treatment has recipes to help you cope with a number of side effects that can affect your ability to eat during treatment.