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Ulcerative Colitis vs Crohn’s Disease: How These Bowel Diseases Differ

Ulcerative Colitis vs Crohn’s Disease: How These Bowel Diseases Differ

Experts compare ulcerative colitis vs Crohn's disease, including symptoms, types, and how they affect your overall digestive health.

It’s understandable if you confuse ulcerative colitis with Crohn’s disease. Both of these chronic conditions are a type of inflammatory bowel disease that targets the digestive system with painful and burdensome symptoms. They both cause stomach pain and cramping, an urgent need to move the bowels, diarrhea, and fatigue. And they both have two phases of activity: flares (a recurrence of symptoms) and remission. On the surface, it can be hard to tell these inflammatory bowel diseases apart.

When it comes to ulcerative colitis vs. Crohn’s disease, the key differences lie where they are located in the body.

Where is ulcerative colitis located in the body?

Ulcerative colitis occurs in the digestive tract but is confined to the colon (also known as the large intestine). It is marked by continuous inflammation of the inner lining of the rectum (the last six inches of the large intestine) and colon. This condition is an autoimmune disease, and the abnormal immune response causes inflammation and ulcers in the colon.

The damage can be confined to the rectum or spread to the higher regions of the colon. In both conditions, inflammation can also occur in other parts of the body, affecting the joints, eyes, and liver.

Where is Crohn’s disease located in the body?

While ulcerative colitis has limitations in its spread, Crohn’s disease can manifest anywhere in the digestive tract, from the mouth to the anus. More often it presents at the end of the small intestine and beginning of the colon.

Like ulcerative colitis, it is triggered by an abnormal immune response that causes too much inflammation. This affects the full thickness of the bowel wall-not just the inner lining, as seen in ulcerative colitis-and causes ulcers. That sounds like a substantial area that is affected, but with Crohn’s disease, there can be healthy patches of the intestine mixed in between diseased patches.

Risk factors for ulcerative colitis and Crohn’s disease

An estimated 3 million adults (about 1.3 percent) have ulcerative colitis or Crohn’s disease. Both conditions affect men, women, and children, and can occur at any age.Ulcerative colitis is most often diagnosed in people in their mid-30s. Crohn’s disease is usually diagnosed between ages 20 and 30.

You might think that the conditions are related to food intolerances (after all, it involves belly pain and frequent trips to the bathroom), but that’s not the case.Research is ongoing, but for now experts know there are a few factors that increase the risk of developing either disease.

First, there’s the immune system. Normally, the immune system is on our side, attacking and killing viruses, bacteria, and other microorganisms we don’t want in our bodies. But in ulcerative colitis and Crohn’s disease, the immune system doesn’t retreat. Instead, it stays in the “attack and kill” mode, which results in excessive inflammation.

Second, family history is a risk factor. People who have inherited inflammatory bowel disease genes are more susceptible to it. The genetic risk is greater in Crohn’s disease; about 15 percent of people with Crohn’s have a first-degree relative with the disease.

Third, unknown environmental factors may trigger the overzealous immune response.

Symptoms of inflammatory bowel disease

The recurring bouts of diarrhea and belly pain that sent people to the doctor are hallmark signs of both ulcerative colitis and Crohn’s disease. Despite their similarities, the two inflammatory bowel diseases can differ in how symptoms present.”I have found that patients with ulcerative colitis tend to have more diarrhea, which can be bloody at times,” says Rahul Nayak, MD, a gastroenterologist with Kaiser Permanente in Atlanta. “Crohn’s typically presents with more abdominal pain but can also include diarrhea as well.”

Mouth sores and fistulas are unique to Crohn’s disease. A fistula is an abnormal connection between two parts of the body, such as between the bowel and the skin, bladder, and other parts of the bowel.The symptoms of inflammatory bowel disease can be embarrassing, painful, and unbearable at times, but Dr. Nayak says that early and aggressive treatment can reduce or eliminate the possible symptoms and complications.

Treatment depends on the location of the inflammation in the body. That’s why it’s essential to know the different types of ulcerative colitis and Crohn’s disease and the specific symptoms they present.

Types of ulcerative colitis

Ulcerative proctitis

The inflammation is restricted to less than six inches of the rectum. Symptoms include urgent bowel movements, rectal pain, and bleeding from the rectum.

Left-sided colitis

Inflammation expands from the rectum up to the splenic flexure, a part of the colon near the spleen in the upper left abdomen. Proctosigmoiditis, which affects the rectum and lower section of the colon, is a form of left-sided colitis as well. Pain is felt on the left side of the abdomen, with symptoms like diarrhea, loss of appetite, and weight loss.

Extensive Colitis

Inflammation affects the entire colon. Symptoms include belly pain, bloody diarrhea, lack of appetite, and weight loss.
Types of Crohn’s disease


The most common form of Crohn’s disease occurs at the end of the small intestine (known as the terminal ileum) and the colon. Symptoms include pain in the middle or lower right abdomen, cramping and diarrhea, and significant weight loss.

Crohn’s (granulomatous) colitis

The inflammation affects the colon only. Symptoms might include diarrhea, rectal bleeding, abscesses, fistulas, and ulcers around the anus. With this type of Crohn’s disease, joint pains and skin lesions are more common.


In this type, a patchy kind of inflammation presents in the upper half of the jejunum (small intestine). People with jejunoileitis might have belly pain, cramps after eating, and diarrhea. Fistulas can form in severe or prolonged periods of inflammation.


The longest part of the small intestine, called the ileum, is where inflammation occurs in this type of Crohn’s disease. Symptoms include cramping, diarrhea, pain in the middle or lower right abdomen, and significant weight loss. In particularly bad cases, fistulas or inflammatory abscesses can occur in the lower right quadrant of the stomach.

Gastroduodenal Crohn’s disease

Inflammation occurs in the stomach and the duodenum (the beginning of the small intestine). Nausea, vomiting, loss of appetite, and weight loss are the usual symptoms.

Indeterminate colitis

Although it only happens in 10 percent of cases, sometimes the features of ulcerative colitis and Crohn’s disease overlap, rendering it too difficult to define. In this case, the diagnosis is indeterminate colitis.

Treatment for ulcerative colitis and Crohn’s disease

Since ulcerative colitis and Crohn’s disease are inflammatory bowel diseases, the medical approach to treating them is quite similar, both at the onset of the disease and when a flare occurs. Because they are autoimmune diseases, people with these conditions often take drugs that suppress the immune system.

“Many of the medications overlap, with only a few medications distinct to each disease,” says Kelly Cushing, MD, a clinical lecturer and gastroenterologist at Michigan Medicine in Ann Arbor.

For example, people with Crohn’s disease may use the immune suppressor methotrexate and the anti-TNF medication certolizumab pegol, which blocks the inflammation-causing molecule, tumor necrosis factor.

In ulcerative colitis, the anti-TNF medication golimumab and immune-suppressing JAK inhibitor tofacitinib are used. But the goal is the same for both diseases.

“The predominant medication strategy in both diseases is the suppression of an overly active immune system,” says Dr. Cushing.


Before medications are prescribed, expect a colonoscopy.

“A colonoscopy is required as part of the initial evaluation and typically to assess for the effectiveness of therapy,” says Dr. Nayak. And therapy is more effective these days, as new medications really zero in on specific diseased areas.

These medications treat the onset of inflammatory bowel disease and flares—just be sure to ask your doctor these key questions before you head to the pharmacy.

Medications that treat inflammatory bowel disease fall into these drug classes:

Aminosalicylates (anti-inflammatories)
Corticosteroids (immune suppressors)
Immunomodulators (control and suppress the immune system)
Biologic therapies (target specific molecules that cause inflammation)
Janus kinase (JAK) inhibitors (immune suppressors used to treat ulcerative colitis)


Eating foods you can tolerate without aggravating your ulcerative colitis or Crohn’s disease can be a tough order sometimes. There’s no one-size-fits-all diet. What one person tolerates may be a trigger for another. In other words, a food may not cause ulcerative colitis or Crohn’s disease, but it can exacerbate the condition.

It’s critical that you work with your doctor or a registered dietitian to find a tolerable diet plan that avoids triggers. A registered dietitian can help you find the foods you can still enjoy while protecting you from nutritional deficiencies that come from the loss of appetite and weight loss.

Generally speaking, eat smaller meals throughout the day instead of the standard “three square.”

Drink plenty of fluids, but sip slowly and don’t use a straw, which can cause gas.

Again, a diet should be tailored to the individual, but here are some common trigger foods that aren’t as easy to digest, especially if you’re experiencing a flare. Potential trigger foods for ulcerative colitis or Crohn’s disease include:

Foods with insoluble fibre, such as whole grains, beans, nuts, fruits with skins and seeds, and raw cruciferous veggies like broccoli and cauliflower. These don’t absorb well and are therefore harder to digest.
Foods with lactose, including milk, cheese, whey, and butter
Sugar-free sweeteners (like xylitol, sorbitol, and maltitol) found in certain food and juices
High-fat and greasy foods.
Spicy foods
Alcohol and caffeinated drinks


When medications aren’t working to manage the symptoms of ulcerative colitis and Crohn’s disease, surgery is the next step. Here’s how the surgery options vary for each.

Surgeries to treat ulcerative colitis

About one-quarter to one-third of patients opt for surgery when other treatments aren’t successful in mitigating symptoms. Surgery can be curative for some patients, Dr. Cushing says. A proctocolectomy, which removes the the colon and rectum, is standard. There are two types of this surgery.

A J-pouch surgery-or, by its technical name, proctocolectomy with ileal pouch-anal anastomosis-removes the colon and rectum and uses the ileum (small intestine) to form an internal pouch shaped like a J. With this surgery, you can have regular bowel movements without wearing an external bag, called an ostomy bag, that collects waste.

A proctocolectomy with end ileostomy removes the colon, rectum, and anus. With this surgery, waste empties into an ostomy bag that you wear at all times. This is less common than J-pouch surgery.

Surgeries to treat Crohn’s disease

Surgery doesn’t cure Crohn’s disease, but it can preserve portions of the gastrointestinal tract. About 70 percent of people with Crohn’s disease will need surgery. “Patients with Crohn’s disease may require surgery for a variety of reasons, including the development of an intestinal stricture, an intra-abdominal or perianal abscess, a fistula, or disease that is refractory to medical therapy,” says Dr. Cushing.

Surgeries are tailored to targeted. For instance, you may require a bowel resection to join two sections of a healthy bowel together, or you might need an abscess drained or fistula removed.

Remission with inflammatory bowel disease

People with inflammatory bowel disease strive to achieve remission status—meaning there is no more inflammation or agonizing symptoms. Statistically speaking, about 50 percent of Crohn’s patients will be in remission or have mild disease over the course of five years past initial diagnosis.

Comparatively, in a given year, 48 percent of patients with ulcerative colitis are in remission, 30 percent have mild disease activity, and 20 percent have moderate disease activity.

Remission doesn’t mean you should throw your care plan out the window.

“Once remission has been accomplished, patients need ongoing medications to ensure that they stay in remission,” says Dr. Nayak. You’ll still want to avoid triggers and talk to your doctor about how often to get colonoscopies to screen for colon cancer, as the risk is higher with both ulcerative colitis and Crohn’s disease.

Dealing with ulcerative colitis and Crohn’s disease flares

Ulcerative colitis and Crohn’s disease are unpredictable. The last thing you want to encounter is a surprise attack of diarrhea and belly pain, which can hinder your plans and keep you stuck at home. That’s why it is vital to stay on the plan devised by your care team.

Avoid the things that trigger flares, like missing too many doses of your inflammatory bowel disease medication, stress, and foods on your trigger list. Of course, some things aren’t as easily controlled, like a gastrointestinal infection that might ignite a flare. And if you get sick from a sinus infection or other illness, the antibiotics you take may cause a flare.

When you feel the flare coming on, check in with your doctor, as adjustments to your medications may be warranted.


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