Crohn’s Disease Versus Ulcerative Colitis: What’s the Difference?

The two GI diseases have many symptoms in common, but Crohn’s and ulcerative colitis often require different treatment.

Difference-Between-Crohn's-and-Ulcerative-Colitis-graph-illustration
Crohn's and ulcerative colitis affect different parts of the GI tract.Canva; Everyday Health
If you’re living with chronic gastrointestinal (GI) problems, you may have Crohn’s disease or ulcerative colitis (UC), two inflammatory bowel diseases (IBDs) that together affect approximately 1.6 million Americans. According to the Crohn’s and Colitis Foundation, doctors diagnose as many as 70,000 new cases of these diseases every year.

Crohn’s and ulcerative colitis are both inflammatory conditions involving the digestive system, and people often struggle to distinguish them.

“The most basic difference is that Crohn’s disease can involve the entire GI tract, from the mouth all the way down to the anus, whereas ulcerative colitis is restricted to the colon,” says Louis Cohen, MD, an assistant professor of gastroenterology at Icahn School of Medicine at Mount Sinai in New York City.

Read on to learn more about the subtle yet significant differences between these two diseases and how your treatment options can vary.

What Is Crohn’s Disease

Crohn’s disease is an autoimmune disorder and a form of IBD that causes inflammation and lesions in the gastrointestinal tract. These lesions are most commonly found in the small intestine and the beginning of the large intestine, but they can occur anywhere in the digestive tract. The inflammation caused by the lesions can lead to a range of symptoms, including abdominal pain, diarrhea, rectal bleeding, fatigue, and weight loss. Inflammation can also lead to complications like a bowel obstruction, which requires surgery.

Because Crohn’s can occur in different parts of the digestive tract, there are several different types of the disease, categorized by the specific area of the digestive system that is affected, and whether or not there is “stricturing,” or narrowing, of the GI tract.?

They are:

  • Ileocolitis?affects the end of the small intestine (terminall ileum), and the large intestine.
  • Ileitis?affects only the ileum.
  • Gastroduodenal Crohn's disease affects the stomach and the beginning of the small intestine (duodenum).
  • Jejunoileitis affects the small intestine.
  • Crohn's (granulomatous) colitis affects the large intestine (colon).

The exact cause of Crohn’s disease remains unclear, but it is believed to be a combination of genetic, environmental, and immune system factors. Certain triggers such as diet, stress, and smoking can exacerbate symptoms of the disease.

What Is Ulcerative Colitis?

Ulcerative colitis is another form of IBD that mainly affects the large intestine (colon) through the formation of ulcers along its walls. Telltale symptoms of ulcerative colitis are blood in the stool with mucus, frequent diarrhea, loss of appetite, and tenesmus, or a strong urge to use the bathroom without necessarily having a bowel movement.

Like Crohn’s, ulcerative colitis comes in different forms, per?Mayo Clinic. These are named according to the part of the colon that is affected including ulcerative proctitis, proctosigmoiditis, left-sided colitis, and pan-ulcerative or total colitis, which affects the entire colon.

As with Crohn’s disease, we don’t know exactly what causes ulcerative colitis, but genetics and immune system malfunction both seem to play a role. While it is not a common occurrence, there have been some instances of patients whose diagnoses change from ulcerative colitis to Crohn’s after?certain surgical treatments.

Why Do People Confuse Crohn’s and UC?

Both UC and Crohn’s are inflammatory conditions involving the digestive tract and present with similar symptoms including diarrhea, abdominal pain, rectal bleeding, and severe weight loss in kids. Because both tend to develop in teenagers and young adults, and affect men and women equally, according to UCLA Center for Inflammatory Bowel Disease, it can be difficult to tell which disease you have, and only a doctor can properly diagnose you with a combination of imaging and endoscopic evaluation. If you suspect that you may have Crohn’s or ulcerative colitis, pay close attention to your symptoms so you can describe them to a GI specialist.

People who suffer from colitis experience continuous inflammation that starts at the sigmoid colon (the lower part of their colon), and are at a higher risk for colorectal cancer. People with UC may also experience rectal bleeding or blood in their stool more often than those with Crohn’s disease, according to Temple Health.

Crohn's disease usually results in healthy stretches of the intestine between inflamed areas, according to UCLA. (These are also referred to as skip lesions.) Some unique symptoms of Crohn’s include mouth sores, fistulas, ulcers, infections, and stricturing, or narrowing of the intestine.

Symptoms of Crohn’s vs Ulcerative Colitis

Symptom
Crohn’s Disease
Ulcerative Colitis
Abdominal pain and cramping
X
X
Fatigue
X
X
Blood in stool
X
X
Diarrhea
X
X
Weight loss
X
X
Mouth sores
X
Ulcers
X
X
Narrowing of intestine
X
Higher risk of colorectal cancer
X
X

How Do I Get Properly Diagnosed?

The gold standard of IBD diagnosis is a colonoscopy, in which a small camera attached to a thin tube is inserted into the colon, allowing a doctor to see the entire colon and part of the small intestine and take biopsies. If the doctor sees that the inflammation starts at the rectum and moves continuously up the colon and then stops, this could be a sign of ulcerative colitis. If, however, the doctor sees nflammation in the digestive tract, with patches of healthy tissue interspersed with patches of inflamed tissue, this could be a sign of Crohn's.

Crohn’s sometimes creates clusters of immune cells called granulomas, whereas ulcerative colitis does not. Granulomas are the result of your body’s attempt to get rid of foreign material, and the cells are visible under a microscope, according to a research article published in September 2022.

If the doctor suspects that the small intestine is involved in Crohn’s, she or he can use an imaging test, including a magnetic resonance imaging (MRI) or CT scan, to get a better look. If part of the upper GI tract, such as the stomach, is involved, your doctor may perform an upper endoscopy to determine where the inflammation is. Doctors may also inspect a stool sample for signs of mucus or blood, which could indicate UC. Stool samples can also help doctors rule out other issues, like pathogens or bacteria.

While it is usually obvious to a gastroenterologist if a person has Crohn’s disease or ulcerative colitis, there are some cases where it is not totally clear which one is causing the inflammation. This is called indeterminate colitis and may affect around 10 percent of people with IBD.

Warning Signs

People living with IBD often experience periods of flare-ups where symptoms are at a high, and periods of remission where symptoms may go away completely. Symptoms can be mild or severe and may gradually appear or start suddenly. Be on the lookout for the following signs:

  • Abdominal pain
  • Diarrhea
  • Gas and bloating
  • Loss of appetite
  • Unexplained weight loss
  • Mucus or blood in stool
  • Upset stomach

Treatment

Crohn’s disease and ulcerative colitis are generally treated with the same types of medication, although patients may respond differently to the same drug. The goal of treatment is to reduce the inflammation, which in turn reduces symptoms, allows your body to repair damaged tissue, and helps slow the progression of the disease.

Today, many IBD patients take a class of drugs called biologics, which are live antibodies that help immune cells fight inflammation. Other classes of drugs include immunomodulators, which tamp down the immune system’s inflammatory response, and aminosalicylates, the oldest class of drugs, which are used to keep the disease in remission.

A newer type of drug, called Janus kinase inhibitors, or JAK inhibitors, are small molecule compounds that are absorbed into the bloodstream and can block multiple pathways of inflammation. “JAK inhibitors are being used most frequently in patients with moderate to severe disease that have failed other therapies,” Dr. Cohen says. “There is an active area of research considering the potential use of JAK inhibitors as first line therapies, especially in patients with more severe disease due to their rapid onset of action.”

Diet is another important factor in flare-ups of both diseases. While everybody is different, high-fiber vegetables like broccoli and cauliflower, uncooked produce, and unpeeled fruit are typically foods that people with IBD have difficulty digesting. Dairy and fatty or greasy foods can also trigger symptoms in some people. A recent AGA clinical practice update states, "unless contraindicated, all patients with IBD follow a Mediterranean diet while minimizing salt, sugar, and ultraprocessed foods.” Work with a dietitian to determine which foods you can safely eat and which ones you should avoid.

Surgery presents an additional avenue for symptom relief in both Crohn’s and ulcerative colitis cases. For ulcerative colitis, procedures such as a colectomy or J-pouch surgery offer relief when medication fails. Meanwhile, in Crohn’s disease, surgery is often necessary to remove damaged sections of the intestine or repair fistulas. Though it is an effective option, a 2019 study published in the Journal of Gastrointestinal Surgery found that surgery is also becoming less common due to medical advancements.

Editorial Sources and Fact-Checking

Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.

Sources

  1. The Facts About Inflammatory Bowel Disease. Crohn’s and Colitis Foundation of America. November 2014.
  2. Ulcerative Colitis. Mayo Clinic. September 16, 2022.
  3. Keighley MR. The Final Diagnosis in Pouch Patients for Presumed Ulcerative Colitis May Change to Crohn’s Disease: Patients Should Be Warned of the Consequences. Acta Chirurgica Iugoslavica. 2000.
  4. Ulcerative Colitis vs. Crohn’s Disease. UCLA Health.
  5. Crohn’s Disease vs. Ulcerative Colitis. Temple Health.
  6. Ulcerative Colitis vs Crohn’s. UCLA Health.
  7. Williams O et al. Granuloma. StatPearls. September 19, 2022.
  8. Ulcerative Colitis vs Crohn’s Disease. UCLA Health.
  9. Inflammatory Bowel Disease (Overview). Cleveland Clinic.
  10. Pass W. AGA Offers Practical Advice on IBD Diets. GI & Hepatology News. March 8, 2024.
  11. Ghoz H et al. Decreasing Colectomy Rates in Ulcerative Colitis in the Past Decade: Improved Disease Control? Journal of Gastrointestinal Surgery. December 3, 2019.
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