Constipation

Approved by the Cancer.Net Editorial Board, 09/2023

Constipation happens when stools (feces) become less frequent, painful, or dry and difficult to pass. Constipation starts when the body absorbs more water or food moves through the bowels more slowly. It is a common symptom for people with cancer. There are treatments available to help relieve constipation and make patients more comfortable when passing stools.

Treating and relieving side effects like constipation is an important part of cancer care and treatment. This is called palliative and supportive care. Talk with your health care team about any symptoms you have, including new symptoms or changes in how you feel.

What are the symptoms of constipation?

In addition to not being able to empty the bowel, people with constipation may experience:

  • Pain and cramping

  • Swelling in the abdomen

  • Hard or dry stool

  • Appetite loss

  • Nausea and vomiting

  • Not being able to urinate

  • Overflow diarrhea, which is when loose stool leaks around harder or impacted stool

  • Rectal bleeding, which is caused by straining to have a bowel movement

  • New, changing, or persistent confusion

Your health care team can help you manage the symptoms of constipation. It is also important to talk with your health care team if your symptoms are new, changing, or ongoing. Constipation can be a sign of a more serious problem and you may need more tests to learn more about the problem and find a treatment that works.

What are the causes of constipation when you have cancer?

Most people experience constipation from time to time. Common causes of constipation for everyone include:

  • Not eating enough food with fiber

  • Not drinking enough water or fluids

  • Not getting regular exercise

In addition to these causes, people diagnosed with cancer may have other causes of constipation. For example, your cancer treatment may be causing constipation. For instance, pain medicine can slow down muscles in your digestive tract, making it more difficult to pass your stool. Your digestion can also be affected by iron supplements, chemotherapy, and supportive care drugs that are used to treat nausea, vomiting, seizures, depression, diarrhea, or high blood pressure.

In addition to medication, people with cancer may have other causes of constipation. These include:

  • Scar tissue from surgery or cancer growing in the bowel, which can narrow or partially block your bowel

  • A tumor or scar tissue completely blocking the bowel, called a bowel obstruction

  • Cancer pressing on the spinal cord

  • High levels of calcium in the blood, called hypercalcemia

  • Low potassium levels

  • Thyroid gland problems

  • Diabetes

Diagnosing constipation when you have cancer

If you have constipation, let your doctor know. Your doctor may recommend a rectal examination or an x-ray or other imaging scans. This is to learn more, including whether there is a tumor blocking your rectum or digestive tract. These tests also help find out if there is hard stool in your rectum.

During your exam, your health care team may ask you about your bowel habits and how they have changed, what medicines you're taking, what you eat and drink, and any other illnesses.

How is constipation managed?

It is very important to treat constipation properly when you have cancer. Without treatment, constipation may damage the intestine or rectum. It can lead to dehydration, block your bowel, and may slow your body's absorption of medicine. If there is scar tissue or a tumor causing the problem, you may need to have more tests and treatment. This could include being hospitalized for medical monitoring, bowel rest, and fluids. Occasionally, surgery or other medical procedures are needed to decompress the bowel and allow stool to pass through.

Talk with your health care team about the best ways to manage constipation. Some of the following suggestions may help:

  • Drink more liquids

  • Be more active. Learn more about exercising after a cancer diagnosis

  • Ask your health care team about changing the dose or stopping medication that may be causing the constipation

  • Ask your health care team about adding fiber to your diet or taking fiber supplements. If you have scar tissue or a tumor narrowing your bowel, your doctor may recommend a low-fiber diet. This is because the fiber may back up behind the narrower areas of the bowel.

  • Ask your health care team about starting a bowel regimen, such as using stool softeners, laxatives, suppositories, or enemas. But do not use these without first checking with your health care team. Some of these may be harmful. Your team will work with you to create a plan based on your needs from the different treatment options available.

Questions to ask your health care team

Consider asking your health care team these questions about constipation during or after your cancer care:

  • Can any of the medications I am taking cause constipation?

  • Who should I tell if I experience constipation? How soon?

  • Will I need additional tests to find out more about my constipation?

  • What can be done to help manage my constipation?

  • Are there lifestyle changes that could help manage constipation?

  • Should I talk with a registered dietitian? And/or an exercise specialist?

Related Resources

Dehydration

Exercise During Cancer Treatment

Side Effects of Chemotherapy

More Information

National Cancer Institute: Constipation and Cancer Treatment

National Cancer Institute: Gastrointestinal Complications

American Cancer Society: Constipation

ASCO answers; Constipation

Download ASCO's free 1-page fact sheets on Constipation. This printable PDF offers an introduction to constipation, including the causes, risks, prevention, and treatment options. A tracking sheet on the back helps record when and how often constipation occurs.