Colon cancer can cause pencil shaped stools. So can irritable bowel syndrome.

And therein lies the problem when you see skinny poops coming out of you that resemble a pencil shape or how toothpaste looks like coming out of the tube.

Let’s take a closer look at how pencil shaped stools from irritable bowel syndrome might appear different from flattened narrow bowel movements caused by colon cancer.

“Patients are often concerned about the frequency, shape and texture of their bowel movements,” explains Dr. Brian Lacy, MD, of Dartmouth Hitchcock Med Center. He specializes in functional disorders of the gastrointestinal tract and author of “Making Sense of IBS.”

What does a healthy bowel movement look like?

“It is important to first understand what is considered normal with regard to stool frequency,” says Dr. Lacy.

“A large study performed years ago in Britain determined the average range of bowel movements is three per day to three per week.”

Yes, three per week. No need to rush to the milk of magnesia when that happens.

“Stool form can also range from loose to firmer,” continues Dr. Lacy. “This depends on a number of factors, including diet, stress, exercise and medications.

In younger people with IBS, bowel movements can come out pencil shaped or like toothpaste as far as shape and form.

This is caused by colon contractions.

“In the absence of warning signs (low blood count, unintentional weight loss, evidence of blood in the stool or family history of colon cancer in a first-degree relative), the occasional occurrence of ribbon-like stools is usually nothing to be concerned about,” notes Dr. Lacy.

“However, in a patient who is older, or a patient with warning signs as mentioned above, ribbon-like stools could mean something serious, such as a lesion in the colon.”

The lesion could be cancer or it could be a precancerous polyp.

“This should be discussed with your health care provider who can perform a careful abdominal and rectal exam and order tests as appropriate.”

What do pencil shaped stools from colon cancer look like in the toilet bowl compared to IBS skinny poops?

Dr. Lacy explains, “Spasm in the colon which can cause a ribbon like stool is common in IBS patients.

“But, the appearance may be the same as someone who has a partial obstruction or who has colon cancer.

“However, someone with colon cancer likely has other symptoms (weight loss, anemia, blood in the stool).

“That is why those are considered warning signs and warrant evaluation and a colonoscopy.”

Dr. Lacy combines his love of science, medicine and people to uncover the causes of symptoms like stomach pain, gas, bloating, diarrhea, constipation and regurgitation. 
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer.