The Differences and Similarities Between Crohn's Disease and Ulcerative Colitis

Crohn’s disease and ulcerative colitis are the two main types of inflammatory bowel disease (IBD). These are chronic (long-term) conditions that cause digestive system irritation. Both conditions can cause symptoms like abdominal (stomach) pain, diarrhea, and fatigue. While Crohn's and colitis share some similarities, they do affect your body differently.

Symptoms of Crohn’s Disease vs Ulcerative Colitis

The most common overlapping symptoms of Crohn’s disease and ulcerative colitis include:

• Abdominal cramping or pain
• Diarrhea
• Fatigue
• Bloody stools

Other symptoms of both conditions may include:

• Urgent need to use the bathroom (known as tenesmus)
• Anemia
• Loose stools
• Upset stomach
• Appetite changes
• Nutrient malabsorption (not getting enough nutrients from food)
• Unintentional weight loss
• Fever

However, each condition also has its own set of different symptoms. Some of these differences include:

Similarities

Crohn’s disease and ulcerative colitis are classified under the umbrella of IBD. That said, it's natural for both conditions to have some similarities. The key things they have in common are their risk factors, diagnostic process, and treatment options.

Both Conditions Share Similar Risk Factors

The exact cause of both ulcerative colitis and Crohn's disease is unclear. But experts believe that people with any type of IBD experience an abnormal activation of the immune system that affects the gastrointestinal (GI) tract—the tube that connects the organs between the mouth and anus. In simple terms, this means that the immune system attacks your body by mistake. 

However, researchers have found the following factors can increase your risk of either condition:

• Having a family history of IBD
• Eating a diet high in refined sugars and low in fruits and vegetables
• Taking some medications such as antibiotics or hormonal birth control
• Smoking
  

The Testing Process Is Usually The Same

To diagnose Crohn's disease or ulcerative colitis, a healthcare provider will look at your medical history, conduct a physical exam, and order tests. The most common tests for both conditions include blood tests, stool samples, and endoscopy (a type of imaging scan that takes a look inside the intestines).

Each test serves a different purpose. Consider the following:

• Blood tests: Look for inflammation markers and certain proteins that may be a sign of IBD
• Stool samples: Check for blood in the stool, inflammation, infections, and parasites that can help to rule out or diagnose you with IBD
• Endoscopy: Visualizes the intestines and GI tract to detect the location, extent, and severity of inflammation and take tissue samples to test for inflammation

Crohn's and Colitis Use Similar Treatments

If you receive a diagnosis for either Crohn's or colitis, your healthcare provider will develop a treatment plan that is right for you. In most cases, however, both conditions have similar treatment options. These include:

• Anti-inflammatory medications: Lower swelling and inflammation
• Immunosuppressants: Help reduce the abnormal autoimmune response that occurs with IBD
• Biologics: Target specific cells in the immune system to control inflammation, which are usually only used when your condition is more severe
• Surgery: Removes part of the colon or rectum, but is only necessary if you have severe IBD and your body isn't responding to other treatments

Differences

Despite so many similarities, Crohn's disease and ulcerative colitis have key differences, which include how they inflame your body, the presence of complications, and their prevalence rates (or, how common each condition really is).

Inflammation Occurs in Different Organs

Crohn’s disease can cause inflammation anywhere in the digestive tract, from the mouth to the anus (where poop exits the body). Ulcerative colitis mainly affects the colon and rectum. The colon and rectum are the last two sections of the large intestine (the tubes that carry food and stool) before the anus.

It's also worth noting that with Crohn's disease, inflammation occurs in patches with healthy tissue in between—which means that the inflammation can skip certain sections of the digestive tract. This type of pattern is also known as "skip lesions." But ulcerative colitis causes continuous inflammation that is not patchy. The inflammation starts at the rectum and extends up to the colon.

Complications Are Usually More Common With Crohn's Disease

Complications due to IBD are more likely to occur with Crohn's disease than ulcerative colitis. Common complications for Crohn's disease include:

• Fistulas: Fistulas are abnormal connections between two separate organs or between your organs and the skin. Examples include intestinal fistulas (which occur between sections of the intestines) or perianal fistulas (which occur between the rectum or anus to the skin around the anus).
• Anal fissures: Small tears in the lining of the anus.
• Strictures: Narrowed areas in the intestines.
• Abscesses: Pus-filled boils or pockets.

However, this doesn't mean that ulcerative colitis does not come with its own risk of complications. One complication is a toxic megacolon, which occurs when your colon dilates (widens) and releases toxins into the blood. The risk of colon cancer also increases if you have severe inflammation in the colon, which is more common with ulcerative colitis.

More People Experience Ulcerative Colitis

Ulcerative colitis is slightly more common than Crohn’s disease. In the US, about 907,000 people live with colitis, while 780,000 people live with Crohn's. There are also more yearly cases of ulcerative colitis. Approximately 38,000 people a year develop colitis, while 33,000 people receive a diagnosis for Crohn's.

Keep in mind: IBD can affect people of all ages. Ulcerative colitis is more common in teenagers and adults, while Crohn's disease is more common in children than adults. During childhood, IBD is more common in people assigned male at birth. This is in contrast to adulthood, where IBD is more common in people assigned female at birth.

Can You Have Both Crohn’s Disease and Ulcerative Colitis?

Between 5% and 15 % of people with IBD have indeterminate colitis (IC), also known as inflammatory bowel disease unclassified (IBDU). This term is a type of IBD that does not clearly fit the criteria for either Crohn’s disease or ulcerative colitis. It's also important to note that this condition is more common in people who get IBD at a younger age. 

When To Seek Care and Who to Contact

Those who have or think they may have IBD should seek medical attention when they experience the following symptoms:

• Persistent diarrhea
• Severe abdominal pain and cramping
• Blood in the stool
• Unexplained weight loss
• Fever or fatigue that doesn't go away

The Crohn’s and Colitis Foundation provides a list of trusted phone apps that can also help you track and manage IBD symptoms and triggers. 

An initial consultation about your symptoms should be with a primary care provider. But your provider may refer you to a gastroenterologist (a doctor who specializes in digestive disorders) for testing and additional support. You can also find a gastroenterologist on the American College of Gastroenterology's database.

A Quick Review 

Crohn’s disease and ulcerative colitis are two main types of inflammatory bowel diseases (IBD). They have some overlapping symptoms, like abdominal pain and diarrhea. While they share similarities like risk factors, diagnostic processes, and treatment options, there are key differences. The differences between both conditions include where inflammation happens, how common each condition is, and which complications can occur.