Lifestyle

Changes in Bowel Habits That Don’t Go Away Can Signal Colon Cancer. Other Signs Not to Ignore

By Curtis Jones · October 29, 2026

It is easy to blame a change in bathroom habits on something you ate. But a change that sticks around is worth a call to the doctor.

The National Cancer Institute says signs of colon cancer include blood in the stool or a change in bowel habits. Age plays a part. The institute says older age is a main risk factor for most cancers and that the chance of getting cancer increases as you get older.

Many people have no warning at all. The Centers for Disease Control and Prevention says polyps and colorectal cancer don’t always cause symptoms, so you could have them and not know it.

When signs do appear, these are the ones listed by the NCI, the American Cancer Society and the CDC.

A change in bowel habits. The American Cancer Society lists a change in bowel habits, such as diarrhea, constipation, or narrowing of the stool, that lasts for more than a few days. The NCI also lists stools that are narrower or have a different shape than usual.

A feeling of not being finished. The CDC and NCI describe feeling that the bowel does not empty all the way. The cancer society lists a feeling that you need to have a bowel movement that is not relieved by having one.

Blood in or on the stool. The NCI says the blood can be bright red or very dark. The cancer society lists rectal bleeding with bright red blood, and blood that might make the stool look dark brown or black.

Belly pain or discomfort. The CDC lists abdominal pain, aches or cramps that don’t go away. The NCI lists general belly discomfort such as frequent gas pains, bloating, fullness or cramps.

Weight loss you can’t explain. All three sources list losing weight for no known reason.

Weakness and fatigue. The cancer society explains that colorectal cancers can often bleed into the digestive tract. The stool often looks normal, but over time the blood loss can lead to low red blood cell counts, or anemia. The CDC lists low iron in the blood among the symptoms.

These problems often have other causes. The cancer society says infection, hemorrhoids or irritable bowel syndrome can cause many of the same symptoms. Even so, it says it is important to see a doctor right away so the cause can be found and treated if needed.

Screening can find trouble before symptoms start. According to the CDC, the U.S. Preventive Services Task Force recommends that adults ages 45 to 75 be screened for colorectal cancer, and the decision to be screened between 76 and 85 should be made individually. The CDC says screening can find polyps so they can be removed before they turn into cancer, and can find cancer early, when treatment works best.

There are several options. Stool tests such as the fecal immunochemical test, or FIT, are done at home once a year. A stool DNA test is done every three years. A colonoscopy, which lets the doctor find and remove most polyps, is done every 10 years for people without increased risk. The CDC says an abnormal result on a stool test means a colonoscopy is needed to finish the screening process.

People with inflammatory bowel disease, a personal or family history of colorectal cancer or polyps, or certain inherited syndromes may need to start earlier or be screened more often, the CDC says.

This article is for general information and is not medical advice. Talk with your doctor about any lasting change in bowel habits and about which screening test is right for you. This article was produced with the assistance of AI and fact-checked against the sources cited by LightWave Reports.