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Managing Cancer Care


Diarrhea is a common symptom for many people with cancer. It can lead to serious problems or delays in treatment.

What is diarrhea?

When you have more stools in a day than is normal for you it is called diarrhea.  is usually loose or watery and you might have abdominal (belly) pain, cramping, or discomfort.  

Diarrhea can lead to other problems, such as:

What causes diarrhea?

Many people with cancer have diarrhea at some point. Some common causes of diarrhea in people with cancer include:

  • Certain cancers like pancreas, gastric, and colorectal
  • Chemotherapy (chemo), especially 5-fluorouracil (5FU), capecitabine, and irinotecan
  • Immunotherapy, especially immune-checkpoint inhibitors
  • Targeted drug therapy, especially tyrosine kinase inhibitors
  • Radiation therapy to the brain, abdomen (belly), pelvis, bowel, bladder, or reproductive organs
  • Infections such as Clostridioides difficile (also known as C. diff) or neutropenic enterocolitis (also known as typhlitis)
  • Small bowel obstructions (blockages)
  • Graft versus host disease (GVHD) after a bone marrow (stem cell) transplant

Diarrhea from chemo usually starts a few days after getting chemo. But diarrhea from immunotherapy or targeted drug therapy might take weeks or even months to develop.

Your doctor might order tests to try to find the cause, such as:  

  • Stool samples to test for infection
  • Imaging tests such as an x-ray or CT (CAT) scan to look for inflammation or other problems
  • Blood tests to check electrolyte levels and for signs of dehydration (both are common with diarrhea that lasts more than a few days)

What are symptoms of diarrhea?

Diarrhea can be different depending on the person. It depends on what your normal baseline is. Common symptoms include:

  • Frequent loose, watery bowel movements (stools)
  • Blood or mucous in stools
  • Stomach pain or cramps
  • Abdominal (belly) swelling or bloating
  • Nausea or upset stomach
  • Sudden need to have a bowel movement (called urgency)


Call 911 or go to the emergency room

  • If you have bleeding from your rectum that won’t stop
  • If you have sudden, intense belly pain that won’t stop
  • If you can’t urinate (pee) or eat for a day or more


Treatment for diarrhea

Managing diarrhea includes treating the cause as well as the symptoms you might be having.


  • Diarrhea from an infection might need antibiotics or other medicine. Many doctors also suggest avoiding antidiarrheal medicines if your diarrhea is caused by an infection because it might make the infection last longer.
  • Antidiarrheals such as Imodium might be used if the cause of the diarrhea isn’t an infection such as C. diff.
  • Steroids are used for diarrhea caused by immunotherapy.
  • If you’re very dehydrated from diarrhea, you might also get fluids and electrolytes.

Food and fluids

Avoid these:

  • Caffeine and alcohol
  • Foods that upset your stomach
  • Spicy foods and foods high in fat or sugar
  • Acidic drinks, such as tomato juice, citrus juices, prune juice, and fizzy drinks.

Try these:

  • A clear liquid diet (water, weak tea, apple juice, peach or apricot nectar, clear broth, popsicles, or Jello) when diarrhea starts or when you feel that it’s going to start.
  • The BRAT diet (bananas, rice, applesauce, and toast) when you’re ready to eat solid foods.
  • Other good foods to try are potatoes, noodles, pasta, cereal, boiled vegetables, and low-salt soup.
  • Drink at least 1 cup of liquid (such as water, sports drinks, or bouillon) after each loose bowel movement to replace lost fluids.  
  • Take medicine for diarrhea only if and as prescribed.

See Dehydration and Lack of Fluids for more information.

Tips for managing diarrhea

Here are some other tips might be helpful if you have diarrhea:

  • Avoid tobacco
  • Avoid supplements including aloe, milk thistle, saw palmetto, ginseng, coenzyme Q10, green tea, and large amounts of vitamin C.
  • Track the amount and frequency of bowel movements.
  • Use dampened toilet paper or baby wipes to clean yourself to help soothe sore areas.
  • Sitting in a tub of warm water or a sitz bath may help reduce pain or discomfort.
  • Applying petroleum ointment to the anal area can help soreness.

Talk to your doctor or cancer care team

If you have diarrhea, make sure your cancer care team knows about it. Diarrhea can lead to serious problems if it isn’t managed.

Tell them if you:

  • Have diarrhea for more than 24 hours
  • Can’t keep liquids down for more than 24 hours
  • Notice any blood in your stool
  • Have a fever (ask what temperature counts as a fever)

Ask your doctor or cancer care team what symptoms you should about call right away versus what can wait until office hours. Make sure you know who to contact when the office is closed.

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 editors and translators with extensive experience in medical writing.

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Grover S, Wang Y, & Dougan M. Immune checkpoint inhibitor colitis. UpToDate. UpToDate Inc; 2023. Updated May 2023. Accessed December 19, 2023.

Krishnamurthi SS and Macaron C. Management of acute chemotherapy-related diarrhea. UpToDate. UpToDate Inc; 2023. Updated December 2022. Accessed December 19, 2023.

Krishnamurthi SS and Kamath SK. Chemotherapy-associated diarrhea, constipation, and intestinal perforation: pathogenesis, risk factors, and clinical presentation. UpToDate. UpToDate Inc; 2023. Updated November 2023. Accessed December 19, 2023.

Lamont JT, Bakken JS, and Kelly CP. Clostridioides difficile infection in adults: Epidemiology, microbiology, and pathophysiology. UpToDate.  UpToDate Inc; 2023. Updated January 2023. Accessed December 19, 2023.

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Last Revised: April 22, 2024

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