Irritable bowel syndrome (IBS) and colon cancer may share several common symptoms, but living with IBS does not increase someone’s risk of developing colon cancer.

IBS is a chronic condition that causes abdominal pain and other symptoms. The condition affects the large intestine, also known as the colon.

Colon cancer affects the same area as IBS and can cause several of the same symptoms in some people.

This article reviews the similarities and differences between symptoms of IBS and colon cancer.

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People living with IBS may experience one or more symptoms. Some of the most common symptoms of IBS include:

  • abdominal pain, often related to bowel movements
  • changes in bowel movements, which can include constipation, diarrhea, or possibly both

People assigned female at birth may also experience increased symptom severity around their period.

Other common symptoms of IBS can include:

  • whitish mucus in stool
  • feeling as though a bowel movement is not finished
  • bloating

Though IBS can be painful, it does not lead to other complications of the gastrointestinal (GI) tract.

Colon cancer often does not cause symptoms right away. It can take several years for symptoms to develop. The American Cancer Society notes that several conditions could cause similar symptoms to colon cancer and should be ruled out during diagnosis.

It states that common symptoms of colon cancer can include:

  • abdominal pain or cramping
  • change in bowel habits, including a narrowing of the stool, diarrhea, or constipation that lasts for more than just a few days
  • rectal bleeding bright red blood
  • dark brown or black blood in stool
  • feeling a need to pass a bowel movement without relief
  • unexplained weight loss
  • weakness or fatigue

IBS and colon cancer share some common symptoms, but there are some important distinctions to keep in mind. The table below highlights common symptoms of both colon cancer and IBS, and symptoms unique to each condition.

SymptomColon cancerIBS
excess gas or bloatingXX
pain or cramps in abdomen associated with bowel movementsXX
feeling of incomplete bowel movementXX
changes in bowel movements and habits lasting more than a few daysXX
unexplained weight lossX
bleeding from rectumX
stool appears narrow X
dark stool or blood in stoolX
a whitish mucus appears in stoolX

IBS can cause discomfort and pain in the abdomen. However, because it does not cause inflammation or other damage to the GI tract, it does not increase a person’s risk of developing colon cancer.

In a 2010 trial study of over 900 people, researchers noted similar results. They found that people with suspected IBS had the same risk of developing cancer as those living with healthy bowels.

A doctor often does not need to perform diagnostic testing to diagnose IBS. However, they may order tests if they suspect something more serious, such as colon cancer.

A person’s doctor will likely perform a physical as well as ask several questions about a person’s:

  • current symptoms
  • medications
  • family history of bowel issues
  • medical history

According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), to diagnose IBS, a doctor typically needs to review a person’s symptoms. If a person has two or more of the following symptoms along with abdominal pain, a doctor may diagnose IBS:

  • pain related to bowel movements
  • changes in stool appearance
  • frequency of bowel movements change

A doctor may also look at how long symptoms have been present. The NIDDK notes that a doctor may diagnose IBS if symptoms began at least 6 months prior, and occur at least once a week for 3 months or more.

During an initial examination and questioning, a doctor will also likely ask about any other potential symptoms. Blood in the stool, rectal bleeding, weight loss, or anemia may indicate another condition could be causing the symptoms.

If a doctor suspects another condition may be causing the symptoms, they will likely order more diagnostic testing. Some tests they may ask for include:

  • colonoscopy
  • CT or CAT scan
  • biopsy
  • protein and gene testing
  • ultrasound

Occasional pain, constipation, or other symptoms often do not require a visit to the doctor. However, if symptoms persist or get worse, a person may wish to speak with a medical professional.

A doctor will likely review a person’s age, overall health, family history of colon cancer, and other risk factors for cancer. If they determine a person’s symptoms may indicate cancer, they may order a CT scan or colonoscopy.

Since IBS symptoms can be similar to inflammatory bowel disease (IBD), a doctor will likely want to rule out IBD. IBD is an autoimmune disease that causes prolonged periods of inflammation, which can put a person at higher risk of developing colon cancer.

IBS and colon cancer share similar symptoms. However, with colon cancer, a person may experience unexplained weight loss, blood in their stool, or bleeding from the rectum that does not occur in IBS.

Despite similar symptoms, IBS does not put a person at higher risk of developing colon cancer. A person may wish to speak with their doctor if they have persistent symptoms of IBS, to help determine the exact cause of the symptoms and recommend treatment.