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Constipation is a condition in which the stool is hard and dry and difficult to pass. The stool becomes hard and dry if it moves too slowly through the large intestine (bowel) or if the intestine takes too much water from it. Constipation affects about one-half of all people with cancer.


People with cancer can have constipation for a number of reasons, including the cancer itself or cancer treatments. The cells lining the gastrointestinal (GI) tract divide rapidly, so they can be easily damaged by chemotherapy and radiation therapy. Factors that increase the risk of developing constipation include:

  • lowered fluid intake and dehydration
  • loss of appetite (anorexia)
  • lack of fibre or bulk-forming foods in the diet
  • vitamin or mineral supplements such as iron or calcium pills
  • overuse of laxatives
  • low level of physical activity or a lot of bed rest
  • thyroid problems
  • depression
  • high levels of calcium or potassium in the blood
  • cancer growing into the large intestine (bowel) or pressing on the spinal cord

Certain drugs that are used to treat cancer or the side effects of treatment can also cause constipation. These include:

  • pain relievers, especially opioid narcotic medicines, such as morphine or codeine
  • chemotherapy drugs such as the vinca alkaloids, which include vincristine (Oncovin), vinblastine (Velbe) or vinorelbine (Navelbine)
  • antinausea drugs such as ondansetron (Zofran), granisetron (Kytril) or dolasetron (Anzemet)
  • anticonvulsant drugs


Symptoms of constipation can vary depending on their cause and other factors. Symptoms of constipation include:

  • bloating or feeling of fullness
  • cramping or pain
  • gas, or flatulence
  • belching
  • loss of appetite
  • no regular bowel movement for 2 or more days
  • straining to have a bowel movement
  • small hard stools that are difficult to pass
  • rectal pressure
  • leakage of small amounts of stool resembling diarrhea
  • swollen, or distended, abdomen
  • nausea or vomiting

If constipation lasts a long time, a large amount of stool can collect. The stool can get packed in the colon or rectum. This is called fecal impaction. Sometimes the stool tries to move around the impaction and can leak from the body. Fecal impaction can become a serious problem, so it is important to try to prevent constipation and impaction.

If symptoms get worse or don’t go away, report them to your doctor or healthcare team without waiting for your next scheduled appointment.


Your doctor will try to find out the cause of constipation. This may include asking questions about your symptoms, bowel movement patterns, medicines and treatments. Your doctor may do a physical exam, including a digital rectal examination, or DRE. A DRE is used to check for packed stool in the rectum, which is called fecal impaction.

You may need to have the following imaging tests if cancer is suspected:

  • abdominal x-ray
  • barium enema
  • endoscopy such as sigmoidoscopysigmoidoscopyA procedure that uses an endoscope (a thin, tube-like instrument with a light and lens) to examine or treat sigmoid colon (the last part of the colon) and rectum. or colonoscopycolonoscopyA procedure that uses an endoscope (a thin, tube-like instrument with a light and lens) to examine or treat the colon.

Preventing constipation

The best way to manage constipation is to prevent it. You can try the following to help prevent constipation.

Eat more fibre

Fibre draws water into the stool and softens it, which makes it easier to pass. Sources of fibre include:

  • whole grain breads and cereals
  • brown rice
  • raw fruit and vegetables
  • legumes, or beans
  • dried fruit
  • popcorn
  • seeds and nuts

Gradually add more fibre and roughage to your diet. When starting a high-fibre diet, increase fibre by 5 grams per day.

Drink plenty of fluids

Try to drink 8–10 glasses of fluid throughout the day to help move the extra fibre through the bowel. Fluids include water, prune juice and other fruit and vegetable juices, nectars, decaffeinated teas, lemonade, broth, gelatin and popsicles.

You can also try hot drinks, such as cocoa, tea or hot water with lemon, to help stimulate the bowels. Eat a breakfast that includes a hot liquid and foods high in fibre.

Eat natural laxatives

Some foods act as natural laxatives. These include prunes, prune juice, rhubarb and papaya. Add small amounts of bran to cooking or baking or sprinkle it on cereal. Avoid foods that can cause constipation, such as cheese, chocolate and eggs.

Talk to a dietitian about ways to prepare and use natural laxative foods in a daily diet. You can also try fruit lax, a jam-type spread made from prunes, dates and other dried fruit. You can make and spread it on toast or crackers or add to ice cream or yogurt.

Increase physical activity

If you can, try to do more physical activty. Just getting out for a short walk can help. Check with your healthcare team before you increase you physical activity.

Managing constipation

Tell your healthcare team if you have difficulty passing stool regularly or if you don’t have a bowel movement for 2 or more days. They will try to find out the cause of constipation and suggest ways to manage it. Keeping a record of your bowel movements may help the healthcare team find ways to relieve constipation. They will also collect information about what you eat and drink, if you are exercising and which medicines you take. Your doctor may have to do a physical exam.

Check with the healthcare team before you use over-the-counter medicines to treat constipation. If you are taking opioid narcotic drugs to relieve pain, your healthcare team will recommend a bowel routine to prevent constipation.

The healthcare team may suggest one of the following to help manage constipation.

Stool softener

Stool softeners help the stool hold water to keep it soft. An example is docusate (Colace, Surfak).


Laxatives may be used to help promote, or stimulate, bowel activity. Examples of laxatives that do this include senna or sennosides (Senokot), magnesium salts (Milk of Magnesia), mineral oil and lactulose.

Laxatives may also be used to increase fibre or produce bulk. Psyllium (Metamucil) is an example of this type of laxative. These types of laxatives are not usually recommended for people who have constipation due to pain medicines or opioids. Pain medicines slow down the bowel, so adding extra fibre doesn’t help. If you are taking pain medicines or opioids, talk to your healthcare team about taking daily stool softeners and a stimulant type of laxative to prevent constipation.

Laxatives may be given as a suppository placed in the rectum. Suppositories can help promote bowel activity. Examples include glycerine and bisacodyl (Dulcolax).

An enema may be used to clean out the bowel or deliver laxatives. Examples include phosphate enema (Fleet) and tap water.

Sometimes a stool softener and a laxative are used together. A suppository or enema may not be recommended when white blood cell or platelet counts are low because of the risk of infection or bleeding when these products are use.

Special considerations for children

Talk to your healthcare team about how you can help prevent or manage your child’s constipation. For younger children, try setting a schedule. Pick regular times after meals when your child sits on the toilet. Even if there isn’t a bowel movement each time, having a schedule may help with constipation.

Check with the healthcare team before giving your child a stool softener or laxative.


Dr Shawn Li I’m extremely grateful to the Canadian Cancer Society for funding my research with an Innovation Grant.

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