Crohn's disease and ulcerative colitis are both forms of inflammatory bowel disease. Crohn's disease most commonly affects the colon and the last part of the small intestine (ileum). Ulcerative colitis affects the colon.
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Inflammatory bowel disease (IBD) is an umbrella term used to describe disorders that involve chronic inflammation of your digestive tract. Types of IBD include:
- Ulcerative colitis. This condition causes long-lasting inflammation and sores (ulcers) in the innermost lining of your large intestine (colon) and rectum.
- Crohn's disease. This type of IBD is characterized by inflammation of the lining of your digestive tract, which often spreads deep into affected tissues.
Both ulcerative colitis and Crohn's disease usually involve severe diarrhea, abdominal pain, fatigue and weight loss.
IBD can be debilitating and sometimes leads to life-threatening complications.
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Inflammatory bowel disease symptoms vary, depending on the severity of inflammation and where it occurs. Symptoms may range from mild to severe. You are likely to have periods of active illness followed by periods of remission.
Signs and symptoms that are common to both Crohn's disease and ulcerative colitis include:
- Fever and fatigue
- Abdominal pain and cramping
- Blood in your stool
- Reduced appetite
- Unintended weight loss
When to see a doctor
See your doctor if you experience a persistent change in your bowel habits or if you have any of the signs and symptoms of inflammatory bowel disease. Although inflammatory bowel disease usually isn't fatal, it's a serious disease that, in some cases, may cause life-threatening complications.
The exact cause of inflammatory bowel disease remains unknown. Previously, diet and stress were suspected, but now doctors know that these factors may aggravate but don't cause IBD.
One possible cause is an immune system malfunction. When your immune system tries to fight off an invading virus or bacterium, an abnormal immune response causes the immune system to attack the cells in the digestive tract, too. Heredity also seems to play a role in that IBD is more common in people who have family members with the disease. However, most people with IBD don't have this family history.
- Age. Most people who develop IBD are diagnosed before they're 30 years old. But some people don't develop the disease until their 50s or 60s.
- Race or ethnicity. Although whites have the highest risk of the disease, it can occur in any race. If you're of Ashkenazi Jewish descent, your risk is even higher.
- Family history. You're at higher risk if you have a close relative — such as a parent, sibling or child — with the disease.
- Cigarette smoking. Cigarette smoking is the most important controllable risk factor for developing Crohn's disease. Although smoking may provide some protection against ulcerative colitis, the overall health benefits of not smoking make it important to try to quit.
- Nonsteroidal anti-inflammatory medications. These include ibuprofen (Advil, Motrin IB, others), naproxen sodium (Aleve), diclofenac sodium (Voltaren) and others. These medications may increase the risk of developing IBD or worsen disease in people who have IBD.
- Where you live. If you live in an industrialized country, you're more likely to develop IBD. Therefore, it may be that environmental factors, including a diet high in fat or refined foods, play a role. People living in northern climates also seem to be at greater risk.
Ulcerative colitis and Crohn's disease have some complications in common and others that are specific to each condition. Complications found in both conditions may include:
- Colon cancer. Having IBD increases your risk of colon cancer. General colon cancer screening guidelines for people without IBD call for a colonoscopy every 10 years beginning at age 50. Ask your doctor whether you need to have this test done sooner and more frequently.
- Skin, eye and joint inflammation. Certain disorders, including arthritis, skin lesions and eye inflammation (uveitis), may occur during IBD flare-ups.
- Medication side effects. Certain medications for IBD are associated with a small risk of developing certain cancers. Corticosteroids can be associated with a risk of osteoporosis, high blood pressure and other conditions.
- Primary sclerosing cholangitis. In this condition, inflammation causes scars within the bile ducts, eventually making them narrow and gradually causing liver damage.
- Blood clots. IBD increases the risk of blood clots in veins and arteries.
Complications of Crohn's disease may include:
- Bowel obstruction. Crohn's disease affects the full thickness of the intestinal wall. Over time, parts of the bowel can thicken and narrow, which may block the flow of digestive contents. You may require surgery to remove the diseased portion of your bowel.
- Malnutrition. Diarrhea, abdominal pain and cramping may make it difficult for you to eat or for your intestine to absorb enough nutrients to keep you nourished. It's also common to develop anemia due to low iron or vitamin B12 caused by the disease.
- Ulcers. Chronic inflammation can lead to open sores (ulcers) anywhere in your digestive tract, including your mouth and anus, and in the genital area (perineum).
- Fistulas. Sometimes ulcers can extend completely through the intestinal wall, creating a fistula — an abnormal connection between different body parts. Fistulas near or around the anal area (perianal) are the most common kind. In some cases, a fistula may become infected and form an abscess.
- Anal fissure. This is a small tear in the tissue that lines the anus or in the skin around the anus where infections can occur. It's often associated with painful bowel movements and may lead to a perianal fistula.
Complications of ulcerative colitis may include:
- Toxic megacolon. Ulcerative colitis may cause the colon to rapidly widen and swell, a serious condition known as toxic megacolon.
- A hole in the colon (perforated colon). A perforated colon most commonly is caused by toxic megacolon, but it may also occur on its own.
- Severe dehydration. Excessive diarrhea can result in dehydration.