Ulcerative Colitis vs. Crohn's: What Is the Difference?

Medically Reviewed By Saurabh Sethi, M.D., MPH
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While both ulcerative colitis and Crohn’s disease refer to chronic inflammation of the gastrointestinal (GI) tract, they are not exactly the same. There are some differences in where they predominantly occur, how they impact the body, and how they are treated. Ulcerative colitis and Crohn’s disease are both types of inflammatory bowel disease (IBD). Collectively, approximately 3 million adults are diagnosed with either ulcerative colitis or Crohn’s disease.

This article will explain the similarities and differences between Crohn’s disease and ulcerative colitis, including their shared symptoms, differences, and which one is considered more severe.

What is the difference between ulcerative colitis and Crohn’s disease?

a man with IBD is lying by a bed with his hand on his stomach
BONNINSTUDIO/Stocksy United

Ulcerative colitis and Crohn’s disease affect different parts of the colon.

While both cause inflammation in the GI tract, ulcerative colitis affects just the colon and rectum (also called the large intestine). In contrast, Crohn’s disease can affect any area of the GI tract. In many cases, Crohn’s disease affects a part of the small intestine.

With ulcerative colitis, inflammation occurs in the innermost lining of the large intestine. With Crohn’s disease, inflammation can affect multiple layers of the entire bowel wall.

Damage from ulcerative colitis covers an area of the large intestine and rectum. Damage from Crohn’s disease shows up in patches of the GI tract, with areas of unaffected tissue in between the inflamed areas.

Do ulcerative colitis and Crohn’s disease share similar symptoms?

There are some shared symptoms between ulcerative colitis and Crohn’s disease. These include:

Visit our video center on IBD here.

Which is worse?

Both ulcerative colitis and Crohn’s disease can be manageable enough for you to live a full and active life.

However, both can cause serious complications, especially if a person does not follow an appropriate treatment plan.

The following table shows the possible complications of both ulcerative colitis and Crohn’s disease.

Ulcerative colitis complicationsCrohn’s disease complications
anemiaintestinal obstruction
bone problemsfistulas
issues with growth and development in childrenabscesses
colorectal canceranal fissures
severe symptoms, including rectal bleedingulcers
perforation of the bowelmalnutrition
toxic megacoloninflammation in other body parts

Indeterminate colitis

When it is difficult to determine whether a condition is ulcerative colitis or Crohn’s disease, doctors may classify the condition as indeterminate colitis.

Specifically, indeterminate colitis means doctors cannot make a definitive diagnosis between the two conditions. An indeterminate colitis diagnosis follows such diagnostic tests as colonoscopy, colonic biopsies, or colectomy.

Are the causes different?

Although there is no known specific cause for either ulcerative colitis or Crohn’s disease, they both develop in response to an irregular immune system.

When the immune system malfunctions in response to environmental triggers, it results in inflammation of the GI tract.

While not confirmed, it is possible there may be a genetic component to an irregular immune system. As such, family history could play a role in who develops ulcerative colitis or Crohn’s disease.

Which diagnosis techniques can tell the difference?

Diagnosing ulcerative colitis and Crohn’s disease starts with documenting your medical and family history, followed by a physical exam by a healthcare professional. Your doctor will also likely order one or more of the following tests:

  • blood tests
  • stool tests
  • endoscopy of the large and small intestines

Learn more about the diagnosis of ulcerative colitis here.

In addition, your doctor may order the following tests to diagnose Crohn’s disease:

  • X-rays of the upper and lower GI tract
  • biopsy of the colon or other area of the GI tract
  • small intestine imaging, such as a CT scan or MRI

Learn more about the diagnosis of Crohn’s disease here.

How are ulcerative colitis and Crohn’s disease treated?

Treatments for ulcerative colitis and Crohn’s disease are similar. They can include the same medications, modifications to diet and nutrition, and, if needed, surgery. Medications for Crohn’s disease or ulcerative colitis can include:

  • Aminosalicylates (5-ASA): These work in the GI lining to reduce inflammation.
  • Corticosteroids: These suppress the immune system.
  • Immunomodulators: These can also suppress the immune system, but are not prescribed unless aminosalicylates and corticosteroids have not been effective.
  • Biologics: These can help treat patients with moderate-to-severe ulcerative colitis as well as patients with Crohn’s disease who have not responded well to other medications.

Dietary changes

Patients with ulcerative colitis or Crohn’s disease should monitor their diets to see if there are certain foods that may trigger inflammation. Bland foods can be better than spicy or high fiber foods, but each individual should pay attention to what they eat and what spurs a flare-up.

Learn diet tips for Crohn’s disease here.

Surgery

The most common form of surgery for Crohn’s disease or ulcerative colitis is ostomy surgery. This involves attaching the end part of the small intestine to an opening in the abdomen. There is a small pouch to collect waste.

Learn more about ostomies here, including information on living with an ostomy.

If ulcerative colitis or Crohn’s disease becomes severe, surgery could be necessary. In ulcerative colitis patients, surgeons remove the colon. In Crohn’s disease patients, they remove the affected portion of the bowel.

In approximately 31% of Crohn’s disease patients who have surgery, they may require a second surgery 10 years after the first.

Differences in treatment

Some differences in treatment for ulcerative colitis and Crohn’s disease include other medications that can specifically treat symptoms of the condition.

For instance, targeted synthetic small molecules can target specific areas of the immune system to reduce inflammation in people with moderate-to-severe ulcerative colitis.

Learn more about treatment for ulcerative colitis here.

Summary

While both ulcerative colitis and Crohn’s disease cause inflammation in the GI tract, they affect different parts of the GI tract. They can cause similar symptoms and may have similar treatment options.

Most people with Crohn’s disease or ulcerative colitis take a form of medication to help manage their condition.

In some severe cases, surgery may be necessary for Crohn’s disease or ulcerative colitis. This could provide relief from symptoms. When a person manages and treats the symptoms of ulcerative colitis and Crohn’s disease, they can maintain a high quality of life.

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Medical Reviewer: Saurabh Sethi, M.D., MPH
Last Review Date: 2022 Apr 26
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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