Ulcerative Colitis vs. Crohn’s Disease: What’s the Difference?

They both fall under the inflammatory bowel disease umbrella.

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Ulcerative colitis (UC) and Crohn’s disease can seem nearly identical at first glance: Both affect digestion, are fueled by inflammatory attacks on the gastrointestinal tract, and can cause similar symptoms, like frequent diarrhea and bloody stools.

UC and Crohn’s disease are both types of inflammatory bowel disease (IBD), which is a category of diseases that causes inflammation in the GI tract due to an inappropriate immune response. The immune system mistakes the GI tract as a foreign invader and attacks, according to UpToDate from Wolters Kluwer. These attacks damage the GI tract over time and lead to digestive distress and abdominal pain.

Crohn’s disease and UC even have similar risk factors. Patients could have the same set of risk factors, but it might play out that one would develop Crohn’s, and the other might develop UC, according to Sergey Khaitov, MD, surgeon at Mount Sinai Beth Israel.

Doctors diagnose the two types of IBD based on where the inflammation is occurring in the GI tract:

  • Crohn’s disease causes inflammation anywhere along the GI tract, from the mouth to the anus. “It may cause a variety of complications related to intestines [or] outside the intestinal tract,” says Dr. Khaitov. The inflammation can occur in patches, leaving unaffected areas in between, and the inflammation can affect several layers of the bowel wall.

  • Ulcerative colitis causes inflammation solely in the colon, also known as the large intestine. Inflammation caused by UC does not occur in patches, and it usually affects just the innermost lining of the colon.

In other words, a key aspect of diagnosing IBD is accurately noting where inflammation is occuring in the GI tract. “If a patient has a picture that’s consistent with ulcerative colitis, it’s possible that they actually have Crohn’s disease,” says Todd B. Linden, MD, gastroenterologist.  For example, if the small intestine was also inflamed, that would indicate Crohn’s.

In some cases, the diagnosis isn’t always clear, or what appears to be UC can progress into Crohn’s. This is known as indeterminate colitis, and about 10 percent of IBD patients experience this.

Whether UC or Crohn’s, many people with IBD experience similar symptoms, such as diarrhea, bloody stools, abdominal pain, urgent bowel movements, constipation, or sensations that the bowel movement is incomplete.

However, symptoms can vary based on the location of inflammation. For example, inflammation on the stomach caused by Crohn’s disease may also lead to loss of appetite, nausea, vomiting, and ultimately weight loss.

Symptoms specific to UC include ulcers in the colon (which lend the condition its name). Ulcers are open sores in the lining of the colon caused by repeated inflammatory attacks. They can leak blood and pus into the stool.

Neither UC nor Crohn’s can be cured, but treatment may help control the condition and reduce symptoms. “There’s a lot of overlap between the treatments for Crohn’s disease versus ulcerative colitis, but it’s not always identical,” says Dr. Linden.

The goal of IBD treatment is to reduce inflammation in the body to prevent attacks on the GI tract, leading to remission of the disease. Find out more treatment options for UC here.