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Constipation
Constipation, or difficulty having bowel movements, is a problem for many people with cancer or going through cancer treatment. Understanding the causes of constipation and learning how to prevent and manage it can help you feel better.
What is constipation?
Constipation is when it is difficult to have a bowel movement (poop) or when you aren’t having as many bowel movements as you usually do.
As stool moves through your bowels, some of the water in the stool is absorbed by the colon (the large intestine). The longer the stool stays in the colon, the more water is absorbed. As more water is taken from stool, the stool becomes harder. This can make it harder to have a bowel movement and lead to constipation.
Constipation can lead to other problems, such as:
- Nausea or vomiting
- Hemorrhoids
- Small tears in tissues lining the anus (anal fissures)
- Part of the rectum slipping out of the anus (rectal prolapse)
- Bowel obstruction (blockage)
- Difficulty peeing (urinary retention)
- Not being able to control when urine comes out (bladder incontinence)
Learn more about the digestive system in the 3D Anatomy Gallery.
What causes constipation?
Many people experience constipation from time to time. Constipation is more likely to be caused be diet, lifestyle, or medicines than cancer itself. However, if you have constipation that worries you, talk to your healthcare provider.
Common causes of constipation
- Not being physically active
- Not drinking enough fluids
- Eating a low-fiber diet
- Taking certain medicines, including pain medicines
Constipation is also more common in people age 65 or older.
Medicines that can cause constipation
- Using laxatives more than directed can cause constipation
- Medicines such as opioids, antidepressants, antinausea, and barium sulfate (contrast for CT scans and X-rays)
- Some chemotherapy (chemo) medicines, especially vincristine and other vinca alkaloids
- Immunomodulatory medicines including thalidomide, lenalidomide, and pomalidomide
Cancer-related causes of constipation
- Certain types of cancer, such as ovarian and colorectal
- Advanced cancer
What are symptoms of constipation?
Symptoms can vary from person to person, but often include:
- Fewer bowel movements than usual
- Difficulty or discomfort during bowel movements
- Small, hard bowel movements that may look like pellets
- A bloated belly, sometimes with frequent gas or burping
- Belly pain or cramps
- Nausea or vomiting
- Leakage of small amounts of liquid stool that can look like diarrhea
Bowel movement frequency varies for each person. Having one bowel movement every other day might be usual for one person but might mean constipation for another. Talk with your cancer care team about what is usual for you and when to be concerned about constipation.
The difference between constipation and bowel obstruction
A bowel obstruction (blockage) can cause some of the same symptoms as constipation. But a bowel obstruction happens when the intestines are fully or partially blocked. It is a serious health condition that needs to be treated right away.
Bowel obstruction (blockage) can cause:
- Severe pain
- Not being able to pass gas or stool if the intestines are fully blocked
These symptoms do not improve with diet, medicine, or changes you make at home.
A bowel obstruction is an emergency. Call your cancer care team right away or go to the nearest emergency room.
Call 911 or go to the emergency room
Call 911 or your local emergency number or have someone take you to the nearest emergency room if you:
- Cannot pass any gas or stool
- Have bleeding from your rectum that will not stop
- Have sudden, intense belly pain that will not stop
- Cannot pee (urinate) or eat for 1 day or more
How is constipation treated?
The goal of treating constipation is to have regular, comfortable bowel movements. What you eat affects your bowels. Because of this, the first treatment your care team might suggest will include diet or habit changes to help relieve constipation.
Fiber is a type of carbohydrate that the body cannot digest. It helps to manage sugar (glucose) levels, lower cholesterol, and support digestion. There are 2 main types of fiber: soluble and insoluble. Most plant foods have both.
Insoluble fiber does not dissolve in water. It helps move food through the intestines by adding bulk without removing too much water. This type of fiber is best for preventing and managing constipation.
Soluble fiber dissolves in water and can pull water out of stool. This can make constipation worse because it slows the bowels.
Common sources of soluble fiber include oats, berries, bananas, flaxseed, chia seeds, and psyllium husk. Soluble fiber is better for preventing and managing diarrhea.
Most adults need about 20 to 35 grams of fiber every day.
There are a few types of laxatives. Most of them are taken by mouth (orally).
- Bulk-forming laxatives make the stool swell up to be bulky, softer, and easier to pass.
- Stimulant laxatives irritate nerve endings in the bowel, which causes bowel muscles to move stool along faster.
- Osmotic laxatives draw water into the bowel, making the stool softer and easier to pass.
- Stool softeners make it easier for water to get into the stool, making it softer.
Laxative medicines can be habit-forming and shouldn’t be used for longer than directed.
Always check with your doctor or cancer care team before you start any laxative, including those you can buy at pharmacies or stores (over the counter).
Enemas and suppositories are medicines placed into the rectum through the anus.
- Enemas are liquid and work by softening the stool and lubricating the bowel. Common types include saline, mineral oil, and stimulant enemas.
- Suppositories are soft solids that dissolve or melt at body temperature to soften the stool. Common types include glycerin and bisacodyl suppositories.
Enemas and suppositories are often used for short-term constipation relief. These treatments sometimes work faster than medicines taken by mouth.
These medicines may lead to problems, such as bleeding or infection, in certain people with cancer.
Always check with your doctor or cancer care team before you start taking these medicines, even if they’re available to buy at pharmacies or stores (over the counter).
If you have long-term (chronic) constipation that doesn’t get better with other treatments, talk to your care team. Your provider may prescribe you medicines to help. There are also prescription medicines that can help manage chronic constipation caused by opioid pain medicines.
Pelvic floor muscle (Kegel) exercises can strengthen the muscles that support the bowel, rectum, and anus. Pelvic floor physical therapists are specialists that can help treat incontinence and many other pelvic floor conditions.
The therapist may examine you and use treatments, such as biofeedback, to treat your constipation. Biofeedback uses sensors placed near the anus to show on a screen which pelvic muscles are being used. Therapy done with biofeedback often works better than therapy alone.
You can ask your care team for a referral to a pelvic floor physical therapist. Or if you search for one yourself, check that they are trained in caring for people with cancer.
Contact your insurance to find out whether you need a referral to pelvic physical therapy to cover costs. Learn more about Managing Your Health Insurance and Medical Bills.
What are ways I can manage constipation?
Changes to your daily routine can help with constipation. Your care team can also suggest other options.
- Eat foods that are good sources of insoluble fiber, such as:
- Wheat bran
- Quinoa
- Brown rice
- Potatoes
- Fruits with edible skin
- Almonds, walnuts, and seeds
- Leafy green vegetables
- Slowly increase your fiber intake until you reach your daily goal of 20 to 35 grams of fiber. Adding fiber too quickly can lead to bloating or worsening constipation.
- Drink enough fluids, especially when you eat more fiber.
- Get more physical activity, such as walking. Movement helps the muscles in your intestines move stool along.
- Try to have a bowel movement around the same time each day. Your bowels are more active after eating and walking.
- Place a footrest in front of the toilet. Raising your feet 8 to 12 inches above the ground can make it easier for your body to pass stool.
If gas and bloating happen, you may want to limit foods and drinks, such as:
- Dairy
- Eggs
- Apples
- Avocados
- Beans
- Vegetables including peas, cabbage, broccoli
- Fizzy or carbonated drinks
Gas can also be caused by chewing gum and drinking through straws.
When should I talk to my doctor or cancer care team?
If you have constipation, make sure your doctor or cancer care team knows about it. Constipation can cause serious problems if it is not treated.
Tell your care team if you:
- Have not had a bowel movement in 3 days or more
- Notice any blood in your stool
- Have belly pain or vomiting
Ask your doctor or cancer care team what symptoms you should call about right away. Ask which symptoms you can wait until office hours to call about. Make sure you know who to contact when the office is closed or after business hours.
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- References
Developed by the 黑料大湿Posts Cancer Society medical and editorial content team with medical review and contribution by the 黑料大湿Posts Society of Clinical Oncology (ASCO).
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Last Revised: October 8, 2026
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