Mayo Clinic Health Manager

Get free personalized health guidance for you and your family.

Get Started

Free

E-Newsletter

Subscribe to receive the latest updates on health topics. About our newsletters

  • Housecall
  • Alzheimer's caregiving
  • Living with cancer

Diarrhea: Cancer-related causes and how to cope

Knowing which diarrhea signs and symptoms are routine and which are serious can help you understand when to call your doctor.

By Mayo Clinic staff

The stomach cramps. The frequent trips to the bathroom. Diarrhea is a common side effect in some people receiving treatment for cancer. Diarrhea may also be caused by the cancer itself. But diarrhea can be more than an inconvenience for people with cancer — it can be a sign of something much more serious.

What causes diarrhea in people with cancer?

Everyone gets diarrhea now and then. If you have cancer, the common causes of diarrhea can still affect you. But there are additional causes of diarrhea specific to cancer, including:

Cancer treatment
Several types of cancer treatment can cause diarrhea:

  • Chemotherapy. Chemotherapy tends to kill fast-growing cells. The cells in your hair, the cells in your bone marrow that make your blood, and the cells that line your intestines are among the most rapidly growing cells in your body. Therefore the typical side effects of chemotherapy include hair loss, decreased blood counts and damage to your intestinal lining. If your chemotherapy causes sufficient damage to the lining of your intestine, diarrhea may result. Not all chemotherapy drugs cause diarrhea. Ask your doctor about your specific type of treatment.

    Your doctor can reduce your chemotherapy-related diarrhea by reducing your dose or stopping your chemotherapy. Tell your doctor if you're experiencing diarrhea, especially if you take daily chemotherapy. Severe problems can occur if you continue to take the chemotherapy while having diarrhea.

  • Radiation therapy. Radiation therapy usually focuses treatment directly at your cancer, though in rare cases radiation is given to your whole body. If your tumor is in your abdominal or pelvic area, diarrhea may be a side effect of the radiation. How severe your diarrhea will be depends on your radiation dose. If radiation therapy is causing your diarrhea, it typically resolves once you complete therapy. But the diarrhea can persist for several months after treatment.
  • Surgery. Surgery to remove a tumor can be one of the most effective treatments for cancer. However, if your surgeon must remove certain parts of your intestine in order to remove the cancer, this might alter your intestines' ability to absorb nutrients or fat and may result in diarrhea.
  • Bone marrow stem cell transplant. Chemotherapy and total-body radiation therapy given as part of a bone marrow stem cell transplant can cause diarrhea. Diarrhea can also be a complication of graft-versus-host disease if you received bone marrow stem cells from a donor. In graft-versus-host disease, the transplanted bone marrow stem cells reject your body. One side effect of this may be diarrhea.

Infections
Cancer treatment can make you more susceptible to various infections, which can cause diarrhea. In addition, the antibiotics that may be used to treat an infection can cause diarrhea.

Stress and anxiety
The stress and anxiety that you feel when you're fighting cancer also can cause diarrhea.

Cancer itself
Certain cancers can cause diarrhea, including:

  • Hormone-producing (neuroendocrine) tumors, including carcinoid syndrome and Zollinger-Ellison syndrome
  • Colon cancer
  • Lymphoma
  • Medullary carcinoma of the thyroid
  • Pancreatic cancer
  • Cancers of the bile duct and gallbladder

The duration and severity of your diarrhea depend on what's causing your signs and symptoms. Talk to your doctor about what you can expect and how long your diarrhea will last.

When should you call your doctor?

Diarrhea typically causes stomach cramps and loose, watery stools. Mostly it's an inconvenience. But if your symptoms persist or get worse, it could be a sign of something more serious, such as a bowel obstruction. Diarrhea can also lead to other problems, such as severe dehydration.

Some signs and symptoms are more serious than others are. Call your doctor right away if you have any of the following:

  • Six or more loose bowel movements a day for more than two days
  • Blood in your stool
  • Inability to urinate for 12 hours or more
  • Inability to drink any liquids for more than two days
  • Weight loss due to diarrhea
  • Diarrhea after several days of constipation
  • Dizziness or lightheadedness when standing
  • Passing out
  • Inability to take in more liquids than you pass in stool
  • Severe abdominal pain
  • Overwhelming fatigue

If your diarrhea doesn't seem severe but starts to interfere with your daily activities, such as if you're concerned about leaving home or going somewhere without a bathroom nearby, talk to your doctor. If abdominal cramping is keeping you from your daily activities, discuss this with your doctor, as well.

Next page
(1 of 2)

CA00040

March 1, 2008

© 1998-2009 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. A single copy of these materials may be reprinted for noncommercial personal use only. "Mayo," "Mayo Clinic," "MayoClinic.com," "EmbodyHealth," "Reliable tools for healthier lives," "Enhance your life," and the triple-shield Mayo Clinic logo are trademarks of Mayo Foundation for Medical Education and Research.

Print Share Reprints

Text Size: smaller largerlarger