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Cancer Health Center

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Gastrointestinal Complications (PDQ®): Supportive care - Patient Information [NCI] - Diarrhea

Diarrhea is frequent, loose, and watery bowel movements.

Diarrhea is frequent, loose, and watery bowel movements. Acute diarrhea lasts more than 4 days but less than 2 weeks. Symptoms of acute diarrhea may be loose stools and passing more than 3 unformed stools in one day. Diarrhea is chronic (long-term) when it goes on for longer than 2 months.

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Approximately 1.6 million new cases of cancer are expected to be diagnosed in the United States in 2014.[1] Many patients diagnosed with cancer will eventually require support from a family caregiver. In fact, family caregivers form the foundation of the health care system in the United States, supporting advances in treatment such as multimodality treatment protocols given in outpatient and home settings.[2] Definition: Who Is the Caregiver? Also referred to as informal caregivers, family...

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Diarrhea can occur at any time during cancer treatment. It can be physically and emotionally stressful for patients who have cancer.

In cancer patients, the most common cause of diarrhea is cancer treatment.

Causes of diarrhea in cancer patients include the following:

  • Cancer treatments, such as chemotherapy, radiation therapy, bone marrow transplant, and surgery.
    • Some chemotherapy drugs cause diarrhea by changing how nutrients are broken down and absorbed in the small intestine. More than half of patients who receive chemotherapy have diarrhea that needs to be treated.
    • Radiation therapy to the abdomen and pelvis can cause inflammation of the bowel. Patients may have problems digesting food, and have gas, bloating, cramps, and diarrhea. These symptoms may last up to 8 to 12 weeks after treatment or may not happen for months or years. Treatment may include diet changes, medicines, or surgery.
    • Patients who are having radiation therapy and chemotherapy often have severe diarrhea. Hospital treatment may not be needed. Treatment may be given at an outpatient clinic or with home care. Intravenous (IV) fluids may be given or medicines may be prescribed.
    • Patients who have a donor bone marrow transplant may develop graft-versus-host disease (GVHD). Stomach and intestinal symptoms of GVHD include nausea and vomiting, severe abdominal pain and cramps, and watery, green diarrhea. Symptoms may show up 1 week to 3 months after the transplant.
    • Surgery on the stomach or intestines.
  • The cancer itself.
  • Stress and anxiety from being diagnosed with cancer and having cancer treatment.
  • Medical conditions and diseases other than cancer.
  • Infections.
  • Antibiotic therapy for certain infections. Antibiotic therapy can irritate the lining of the bowel and cause diarrhea that often does not get better with treatment.
  • Laxatives.
  • Fecal impaction in which the stool leaks around the blockage.
  • Certain foods that are high in fiber or fat.
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