Definition of Colitis

In medicine, colitis (pl. colitides) refers to an inflammation of the colon and is often used to describe an inflammation of the large intestine (colon, caecum and rectum).

Colitides may be acute and self-limited or chronic, i.e. persistent, and broadly fits into the category of digestive diseases.

In a medical context, the label colitis (without qualification) is used if:

  • The aetiology of the inflammation in the colon is undetermined; for example, colitis may be applied to Crohn’s disease at a time when the diagnosis has not declared itself, or

  • The context is clear; for example, an individual with ulcerative colitis is talking about their disease with a physician that knows the diagnosis.

There are many types of colitis. They are usually classified by the etiology.

Types of colitis include:


  • Inflammatory bowel disease (IBD) – a group of chronic colitides.
    • Ulcerative colitis – a chronic colitis that affects the large intestine.
    • Crohn’s disease – a type of IBD often leads to a colitis.


  • Microscopic colitis – a colitis is diagnosed by microscopic examination of colonic tissue; macroscopically it is normal appearing.
    • Lymphocytic colitis.
    • Collagenous colitis.


  • Diversion colitis.
  • Chemical colitis.

Vascular disease 

  • Ischemic colitis.


  • Infectious colitis.

A well-known subtype of infectious colitis is Clostridium difficile colitis, which is informally abbreviated as “c diff colitis”. It classically forms pseudomembranes and is often referred to as pseudomembranous colitis, which is its (non-specific) histomorphologic description.

Enterohemorrhagic colitis may be caused by Shiga toxin in Shigella dysenteriae or Shigatoxigenic group of Escherichia coli (STEC), which includes serotype O157:H7 and other enterohemorrhagic E. coli.

Parasitic infections, like those caused by Entamoeba histolytica, can also cause colitis.

Unclassifiable colitides

Indeterminate colitis is a term used for a colitis that has features of both Crohn’s disease and ulcerative colitis. Indeterminate colitis’ behaviour is usually closer to ulcerative colitis than Crohn’s disease.

Atypical colitis is a phrase that is occasionally used by physicians for a colitis that does not conform to criteria for accepted types of colitis. It is not an accepted diagnosis per se and, as such, a colitis that cannot be definitively classified.

Cause of Colitis

Infectious Colitis

Viruses and bacteria can cause colon infections. Most are food-borne illnesses or “food poisoning.” Common bacterial causes include Shigella, E ColiSalmonella and Campylobacter. These infections, with the exception of Campylobacter infection, often cause bloody diarrhea and can lead to dehydration from the loss of fluids in the diarrheal stools.

Parasites such as giardia can cause significant diarrhea. The parasite can enter the body when infected water is swallowed. The source may be from recreational water such as rivers, lakes, and swimming pools. It may also be contaminated from a water well or cistern.

Most commonly the bacterium that overgrows is a bacterium called, Clostridium difficile (C. difficile, C. diff). This bacteria produces toxins that cause diarrhea, usually non-bloody, associated with a fever and is called C. difficile colitis or pseudomembranous colitis (because of the membrane-like clumps of pus that form on the inner lining of the colon). This disorder is often seen in patients who have recently been taking antibiotics for an infection.

Ischemic colitis

The colon can be thought of as a hollow muscle. It requires a supply of blood to bring oxygen and nutrients in order for the muscles to function normally. When the colon loses its supply of blood and becomes ischemic

In persons who are at risk for decreased blood flow to the colon, ischemic colitis can occur if the blood pressure falls. This may occur with dehydrationanemia, or shock.

Ischemia or lack of blood supply causes significant pain, fever, and bloody bowel movements.

Inflammatory Bowel Disease

There are two types of inflammatory bowel disease

  • Ulcerative colitis:Ulcerative colitis begins in the rectum and may gradually spread throughout the colon.  It is thought to be a disease caused by overactivity of the immune system and usually causes abdominal pain, and bloody, diarrheal bowel movements.
  • Crohn’s disease: It may involve any part of the digestive tract from the esophagus and stomach, through to the small and large intestine all the way to the rectum. In Crohn’s disease there may be skip lesions, which is, abnormal segments interspersed between normal segments. If segments of the colon are involved, then symptoms of colitis may be present.

Microscopic Colitis

Two diseases make up this group of colon inflammation, collagenous colitis and lymphocytic colitis. Either collagen or lymphocytes (a type of white blood cell) engorge the layers of the wall of the colon, presumably a result of inflammation. The diarrhea often is watery, but no blood is present in the stool.


Chemical Colitis

Chemicals which are instilled into the colon cause inflammation and damage. One of the complications of an enema is inflammation of the mucosal lining of the colon.


Signs and Symptoms of Colitis

The signs and symptoms of colitides are quite variable and dependent on the etiology (or cause) of the given colitis and factors that modify its course and severity.

Symptoms of colitis may include: abdominal pain, loss of appetite, fatigue, diarrhea, cramping, urgency and bloating.

Signs may include: abdominal tenderness, weight loss, changes in bowel habits (increased frequency), fever, bleeding (overt or occult)/bloody stools, diarrhea and distension.

Signs seen on colonoscopy include: colonic mucosal erythema (redness of the inner surface of the colon), ulcers, bleeding.

Diagnosis of Colitis

Symptoms suggestive of colitis are worked-up by obtaining the medical history, a physical examination and laboratory tests (CBCelectrolytes, stool culture and sensitivity, stool ova and parasites et cetera). Additional tests may include medical imaging (e.g. abdominal computed tomographyabdominal X-rays) and an examination with a camera inserted into the rectum (sigmoidoscopycolonoscopy).

Prevention from Colitis

The lack of clean drinking water and adequate sanitation, poor hand washing and poor kitchen hygiene allow the potential for infectious colitis. Cleanliness is important to prevent it.

Inflammatory bowel diseases are difficult to prevent because it is caused by heredity.

Since ischemic colitis is caused by narrowing of the blood vessels to the bowel, decreasing the risks for other types of circulatory problems such as peripheral vascular disease, heart attack, and stroke will also decrease the risk for ischemic colitis. To prevent it, quit smoking, control high blood pressure, keep cholesterol at healthy levels.

Treatment of Colitis

How a given colitis is treated is dependent on its etiology. Infectious colitis are usually treated with antimicrobial agents (e.g. antibiotics) such as nifuroxazide. Autoimmune mediated colitis is treated with immune modulators/immune suppressants. Severe colitis can be life-threatening and may require surgery.

Ulcerative colitis can often be treated with changes to one’s diet. Although the causes of colitis are not known, the disease can become manifested due to faulty diet. When symptoms such as flatulence, cramping, mucous and bloody discharges and blood on stools begin to occur, the B.R.A.T. diet is recommended. This acronym is derived from bananas, rice, apple sauce and toast. Foods to avoid are dairy products and fried foods.