Table of Contents
Inflammatory Bowel Diseases
- Ulcerative colitis (UC)
- Crohn’s disease
- Behcet’s disease
- Microscopic colitis
- Diverticulosis-associated colitis
- Collagenous colitis
- Lymphocytic colitis
Ulcerative colitis and Crohn’s disease are the two most common forms of IBDs and, as such, it can be easy to confuse the two.
Ulcerative colitis is an inflammatory bowel disease that affects the lining of your colon and rectum. While this is a chronic condition with no known cure, it typically occurs in cycles, and around half of the patients are currently in remission without symptoms. 
Crohn’s disease can cause inflammation in any part of the digestive tract, rather than just the colon. Once again, it is a chronic condition that can be reduced by medication, causing long periods of remission.
Keep reading to learn more about the differences between ulcerative colitis and Crohn’s disease, including their symptoms, causes, and how they can be treated using medications such as mesalamine (Lialda or Asacol) and azathioprine (Imuran).
Where in the Body does UC and Crohn’s Occur?
One of the biggest differences between ulcerative colitis and Crohn’s disease is the location in the body that the condition affects.
a. Where in the Body does Crohn’s Disease Occur?
Crohn’s disease can occur in any part of the digestive tract. The disease may be restricted to just one area of the digestive system or may involve multiple body parts.
The body’s digestive tract includes any part of the body or organs that foods and liquids travel through during digestion. The digestive tract begins at the mouth where food enters the body and finishes in the anus where waste leaves the body. Other key areas of the digestive tract include the esophagus, stomach, small intestine, colon, and rectum. 
b. Where does Ulcerative Colitis Occur?
By contrast, ulcerative colitis affects a far smaller area of the body. UC is confined to the colon or large intestine. There are several different types of ulcerative colitis, depending on where in the colon that the condition affects. These range from proctitis that is confined to the rectum, to pancolitis that affects the entire colon. Usually, if patients have pancolitis, they have initially had another form of UC that spread throughout the large intestine. 
Symptoms of UC and Crohn’s
The symptoms of UC and Crohn’s are very similar. For both conditions, symptoms can range between mild and severe and may disappear completely during long periods of remission.
Common symptoms of both conditions include:
- Severe diarrhea
- Bloody stools
- Rectal pain and bleeding
- Abdominal pain and cramps
- Loss of appetite
- Unexplained weight loss
- Fever  
Causes of UC and Crohn’s
a. What Causes Ulcerative Colitis?
The exact cause of ulcerative colitis is not known. It is believed to be an autoimmune disease that occurs when the body’s immune system does not function correctly. When healthy, the body’s immune system works by attacking and destroying viruses, bacteria, and other foreign substances in the body. However, for UC patients, the immune system believes that food and healthy bacteria are foreign substances. This leads white blood cells to attack the lining of your colon, which causes inflammation. 
Ulcerative colitis may be partially hereditary. The condition is more common in people that have family members with UC. However, the majority of UC patients do not have family members with the condition. 
b. What Causes Crohn’s Disease?
Once again, the exact cause of Crohn’s disease is not known. It occurs in the same way as UC when the body’s immune system does not function correctly. An abnormal response from the immune system results in cells mistakenly attacking healthy body parts. For Crohn’s, this can occur anywhere in the digestive tract, causing inflammation.
Similarly, to UC, Crohn’s disease is believed to be partially hereditary, although once again, most patients do not have any other family members with the condition. It is possible that the initial trigger for Crohn’s disease may be a virus or a type of bacteria. However, this is not confirmed, and researchers have not identified any possible trigger. 
Treating UC and Crohn’s
There are several medications that may be prescribed to treat both ulcerative colitis and Crohn’s disease. When treating both conditions, the first medication prescribed is often a 5-aminosalicylic acid (5-ASA), such as mesalamine (Lialda or Asacol). Mesalamine is an anti-inflammatory drug that works by fighting inflammation in the body. For more severe IBDs, you may be given a corticosteroid anti-inflammatory, rather than a 5-ASA.  
Ulcerative colitis and Crohn’s disease are both believed to be autoimmune diseases caused by the body’s immune system attacking healthy cells. As well as an anti-inflammatory, you may be prescribed an immunosuppressant drug such as azathioprine (Imuran) or mercaptopurine (Purinethol). These immunosuppressants help to prevent the inflammatory response caused by the immune system.  
When your IBD is severe, then you may require surgery. For ulcerative colitis, a proctocolectomy may be required. This surgery removes your entire colon and rectum, replacing them with a new pathway. This new pathway may be re-routed to the end of the rectum, or alternatively, a small hole may be created in the abdomen and drained into an external bag. This surgery is typically used for chronic or severe cases or when there is a risk of serious complications. 
These surgeries may drain abscesses, close fistulas, or remove damaged sections of the digestive tract. However, surgery for Crohn’s disease usually only offers a temporary improvement. 
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