Irritable Colon (Large Intestine) Meaning, Causes, Symptoms

The colon is the last part of the large intestine where stool is formed and stored until it is passed out with a bowel movement. As with any organ, the colon can become diseased and its functioning disrupted. This may sometimes be referred to as an irritated colon, although this is not a specific medical term. The disturbances that may be associated with an irritable colon may be seen in conditions such as irritable bowel syndrome (IBS), inflammatory bowel disease (IBD) and colorectal cancer.

What does an irritable colon mean?

The term ‘irritable colon’ is not a specific medical condition. Instead it is a common term used to describe certain symptoms that are often associated with colon. This may include diarrhea (sometimes constipation or alternating between both), lower abdominal pain and/or cramping, excessive flatulence (gas), bloating (sensation of fullness), urging to pass stool and/or rectal pain and/or bleeding.

All of these symptoms can be attributed to problems with the colon. However, it may also arise with a host of other digestive and abdominal conditions beyond the colon. Sometimes there is no problem with the colon or any other part of the digestive despite the presence of these symptoms. Without proper diagnostic investigations, it can be difficult to identify the exact cause of an ‘irritable colon’.

Read more on sensitive bowels.

Is irritable colon the same as IBS?

Irritable bowel syndrome (IBS) is a condition where there is abdominal pain along with change in bowel habit. The term ‘irritable’ can be misleading as it may insinuate inflammation of the bowel. Usually there is no significant inflammation in IBS. In fact the exact cause of irritable bowel syndrome is not known but it appears to be an abnormality with the movement through the gut and the bowels specifically.

An irritable colon is not necessarily due to irritable bowel syndrome (IBS). Although the colon is part of the bowels (specifically the large intestine), an irritable colon does not clearly indicate the nature of the underlying conditions. As mentioned, an irritable colon can refer to a host of colon and digestive tract conditions other than IBS including inflammatory bowel disease (IBD), diverticulitis, infectious colitis or even colorectal cancer.

Signs and Symptoms

The signs and symptoms of an irritated colon can be diverse depending on the underlying causes. Some of the common signs and symptoms include:

• Diarrhea or constipation
• Watery stool or hard dry stool
• Excessive flatulence (gas)
• Bloating (sensation of fullness)
• Abdominal pain or cramps
• Persistent urge to pass stool
• Incomplete feeling after defecation
• Straining to pass stool
• Blood or mucus in the stool
• Rectal bleeding
• Changes in appetite

There may also be other non-digestive signs and symptoms such as fever, unintentional weight loss and malaise.

Causes of Irritable Colon

Apart from irritable bowel syndrome (IBS), there are other possible digestive and colon conditions that may be referred to as an ‘irritated colon’. Inflammation of the colon (colitis) may also be accompanied by inflammation of the rectum (proctitis). Many of the causes of both conditions are similar.

Foods and Drinks

A number of foods and beverages can cause irritation of the digestive tract and not only the colon. These edibles may not cause inflammation but rather lead to disruption of normal digestive tract functioning. A common example is in food intolerances such as lactose intolerance or malabsorption syndromes such as fructose malabsorption.

In conditions such as lactose intolerance the body is unable to digest milk sugar (lactose). This undigested lactose draws out water into the bowels and causes symptoms like abdominal cramps and diarrhea. A similar disruption occurs with malabsorption syndromes when the body cannot absorb certain nutrients.

Infections

Food poisoning is an infection or exposure to toxins from infectious agents through consuming contaminated food and water. These infectious can also be acquired through other routes such as infectious droplets that may nter through the respiratory passages.

The infection may involve the upper parts of the digestive tract, or the lower parts like the small and large intestine. When the intestines are inflamed then it is known as enterocolitis. Sometimes the colon alone if inflamed with the infection and this is known as colitis.

Most infections are acute and often resolve within a few days to a week. Sometimes treatment is not necessary beyond supportive measures like bed rest and fluid administration to prevent dehydration.

Read more on intestinal infections.

Autoimmune

Inflammatory bowel disease (IBD) is another common condition of the digestive tract. There are two types – ulcerative colitis (UC) and Crohn’s disease (CD) The inflammation may be limited to the large intestine (with ulcerative colitis) or extend to other parts of the gut (like in Crohn’s disease).

The exact cause of inflammatory bowel disease is unknown. For some reason the immune system attacks the bowel wall thereby causing inflammation. Ulcers may also form in the wall of the digestive tract.  There is a risk of cancer associated with IBD but more so with ulcerative colitis.

Read more on IBS vs IBD.

Pouches

Small pouches can form in the colon which are known as diverticula. It is more likely to occur after the age of 40 years. These pouches are more likely to develop with increased pressure as may occur with excessive straining in conditions like constipation.

Diverticula may be asymptomatic meaning that there are no symptoms despite the pouches being present. Sometimes these pouches may become infected or inflamed and this is known as diverticulitis. This may require medication like antibiotics although  surgery may be necessary for severe cases of diverticulitis.

Medication

Some drugs can also cause an ‘irritated colon’.  One common condition that is caused by antibiotics is known as pseudomembranous colitis (also known as C.difficile colitis or antibiotic-associated colitis). It occurs when there is an overgrowth of Clostridium difficile bacteria due to antibiotic use.

Laxatives are another drug that can cause an ‘irritated colon’ especially if it is used in excess. Apart from oral drugs, certain suppositories may also irritate the colon. Radiation therapy to the abdomen and chemotherapy drugs are some of the other modlaities that may lead to an irritated colon.

Cancer

Colorectal cancer is another possible cause of colon symptoms that may be labeled as irritable colon. It is the most serious cause because colorectal cancer is potentially life-threatening. In fact colorectal cancer is one of the most common and deadly forms of cancer.

There are several risk factors for developing colorectal cancer such as being obese, advancing age, smoking, having a polyps or conditions like inflammatory bowel disease (IBD) or a family history of cancer. Apart from many of the common bowel symptoms discussed above, there may also be unintentional weight loss and unexplained fatigue.