Can a Change in Your Bowel Movements Be a Sign of Colon Cancer?

What Your Stool Color, Shape, and Consistency May Reveal

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Bowel movement changes typically aren't something you'd discuss at the dinner table, but you should be comfortable discussing them with your doctor.

Changes in how often you are going to the bathroom, whether you experience constipation or diarrhea regularly, and various other characteristics of your stool are important clues as to what's going on inside your digestive tract.

What Does a Change in Bowel Movement Mean?

A change in bowel movements is unique for each person and the nature of a change can be described as in the following ways:

Change in Stool Frequency

A persistent change (more than a few days) in stool frequency is one potential sign of colon cancer. So, for example, if it is normal for a person to have three bowel movements per day, and he or she is having only one per day, or one every other day, this may signal constipation.

On the other hand, another person's typical bowel pattern may be to have a bowel movement every other day. In this case, having one bowel movement per day may be unusually frequent, and it may signal a change in typical bowel habits.

Change in Stool Color, Consistency, or Shape

A change in what your stool looks like (color or consistency) may also be a sign of colon cancer. Some changes are subtle, like thin or narrow stools whereas others are more obvious, like bright red or dark blood in your stool, nearly black stool, or maroon colored stool. All of these can point to bleeding in the digestive tract.

Difficulty With Stool Evacuation

A persistent feeling that you need to have a bowel movement, even when you just had one (called tenesmus).

Other Symptoms or Signs of Colon Cancer

Other potential signs or symptoms of colon cancer include one or more of the following:

  • Belly pain or cramping
  • Bleeding from the rectum
  • Feeling very tired or weak (from iron deficiency anemia, caused by the colon cancer)
  • Weight loss that is unintentional
  • Loss of appetite
  • A mass that can be felt on an abdominal or rectal exam

It's key to note that the symptoms mentioned above are by no means a slam dunk clue of a colon cancer diagnosis. In fact, they could indicate another problem in the bowels like an infection (for example, acute diverticulitis) or inflammation (for example, Crohn's disease). This is why being evaluated by your doctor is critical. 

Finally, some people have no symptoms, and colon cancer is discovered incidentally on a colonoscopy, possibly after a doctor noticed iron deficiency anemia in a person's blood tests. 

Tell Your Doctor About a Change in Bowel Movements

Depending on your history and physical exam, your doctor may schedule a colonoscopy with a  gastroenterologist—a doctor who specializes in treating diseases of the digestive tract. 

He may also order blood tests, such as a complete blood count and liver enzymes. Finally, depending on your symptoms, he may order imaging tests, like a CT scan, to check for other potential diagnoses like an infection of the bowel.

If you are diagnosed with colon cancer, there are different treatment options depending on the stage of your cancer (whether your cancer has spread, and if so, how far within the body).

A Word From Verywell

The take-home message here is that it's a good idea to know what's normal for you in terms of your bowel movements and how you feel. You certainly don't need to keep a detailed record of your bathroom habits, but if you notice a change from what is typical for you, pay attention. 

If the changes only last a short time, or you know the reason for the change (say, you've been sick or you ate something that doesn't agree with you), you don't need to worry. But if the changes last for more than a few days, get it checked out.

While you may be scared about the possibility of having colon cancer, finding out now is the best way to take care of yourself and get the medical care you need.

In addition, there is a possibility that something entirely else is going on, something less serious than cancer. Regardless, be kind to yourself and get to the bottom of your symptoms.


American Cancer Society. (2017). Colorectal Cancer Signs and Symptoms.

John SK, George S, Primrose JN, Fozard JB. Symptoms and Signs in Patients With Colorectal Cancer. Colorectal Dis. 2011 Jan;13(1):17-25.