Crohn’s Versus Ulcerative Colitis: A Comparison

Medically reviewed by: Gary H. Hoffman, MD

Bowel and rectal disorders afflict all demographics. Some of those disorders present with similar symptoms. Though often confused, Crohn’s disease and ulcerative colitis are two different conditions that distress the colon. Knowing the difference between the two is important.

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Both Crohn’s disease and ulcerative colitis may be defined as an aspect of inflammatory bowel disease or IBD. Both are believed – in some ways more than others – to be linked to genetics, environmental factors and lifestyle, as well as immune system dysfunction.

The pathology of the two however, are different. While the research and contemporary understanding of the pathophysiology of both conditions is often confusing, a layperson naturally focuses only on symptoms. Physicians will not only take into consideration signs and symptoms of bowel disturbances, but also intense examination of a patient’s family history, lifestyle behaviors, and diet to make an accurate diagnosis.

Comparison between Crohn’s Disease and Ulcerative Colitis

When it comes to comparisons, a number of similarities as well as differences will be noted.

Inflammation is common to both ulcerative colitis and Crohn’s disease, although such inflammation can have very different effects on the colon. While inflammation is similar to both conditions, the nature of the inflammation as well as its location in the gastrointestinal tract and its spread and penetration of the mucosal lining of the colon determines the ultimate diagnosis.

Another similarity shared between Crohn’s disease and ulcerative colitis is that the condition often comes in waves, often known as outbreaks or surges. Each are characterized by bouts of irritation, followed by exacerbation that contributes to more severe symptoms. Following care, remission occurs for varying periods before another flare-up takes place. Duration of flare-ups and remissions differ among individuals.

As with similarities, a number of differences are also noted.

Ulcerative colitis is defined as a type of inflammatory bowel disease (IBD) that mainly affects the lining of the large intestine and/or rectum, causing inflammation and irritation.

Crohn’s disease is medically defined as a chronic, long-term disease of the bowel that causes severe inflammation to any portion of the digestive tract – meaning mouth to anus. For many people dealing with Crohn’s, the last portion of the small intestine where it joins the large intestine (cecum) is affected. For others, only the large intestine (colon) may be affected. For most however, the last portion of the small intestine (ileum) and its juncture to the colon is commonly affected.

More simply, ulcerative colitis typically affects the person’s left portion of the colon as well as the rectum.

Crohn’s disease typically occurs in the distal lower portion of the Ilium or ‘right colon’ – more noticeable in the person’s right side but may also flare up in any portion of the gastrointestinal tract.


A dysfunction of the immune system is believed to be a common culprit bot both Crohn’s and ulcerative colitis. In the case of Crohn’s, heredity may play a more important role than it does in the development of ulcerative colitis.

A bacteria or virus can initially prompt an immune response as the body attacks the invading microorganism in the gut. However, this immune response may also trigger the body to abnormally attack its own digestive tract cells.

In the past, it was believed that stress and inadequate diet were more common culprits in causing ulcerative colitis, but this theory has fallen into disfavor, with medical experts now leaning toward a malfunction of the immune system, similar to that in Crohn’s.

An individual diagnosed with ulcerative colitis may experience chronic inflammation affecting the lower colorectal area.Others may experience ulcerative colitis that relatively confined to the rectal area, more commonly diagnosed as ulcerative proctitis.

Comparison of Symptoms of Crohn’s and Ulcerative Colitis

Symptoms of Crohn’s disease and ulcerative colitis are similar. For example, primary symptoms of ulcerative colitis include:

  • Bloody diarrhea
  • Abdominal pain
  • Poor appetite
  • Weight loss
  • Lack of bowel control
  • Chronic fatigue

Symptoms of Crohn’s disease include:

  • Diarrhea
  • Abdominal pain and cramps
  • Fever
  • Fatigue
  • Bloody stools
  • Poor appetite

Because the symptoms are so similar, it can be difficult to differentiate between the two.

When to See a Physician

Brief periods of bowel irregularity are common for most, with many taking a “wait-and-see” attitude. However, a number of indications serve as warnings and should prompt a visit with a physician. Such signs or symptoms include:

  • Abdominal pain that doesn’t ease within a day or two
  • Multiple or recurrent signs of blood in the toilet bowl or in your stool
  • Diarrhea that fails to respond to over-the-counter treatments or change in diet
  • Chronic sense of fatigue
  • Inexplicable weight-loss

A visit to your physician is a good idea for any change in bowel habits. If left untreated, both ulcerative colitis and Crohn’s disease can contribute to a number of potential complications including severe dehydration, bleeding, a perforation, as well as an increased risk of colon cancer.

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