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Inflammatory bowel disease

Inflammatory bowel disease (IBD) involves chronic inflammation of all or part of your digestive tract. IBD primarily includes ulcerative colitis and Crohn’s disease. IBD can be painful and debilitating, and sometimes leads to life-threatening complications.

Ulcerative colitis (UL-sur-uh-tiv koe-LIE-tis) is an inflammatory bowel disease that causes long-lasting inflammation in part of your digestive tract. Symptoms usually develop over time, rather than suddenly. Ulcerative colitis usually affects only the innermost lining of your large intestine (colon) and rectum. It occurs only through continuous stretches of your colon.

Crohn’s disease is an inflammatory bowel disease that causes inflammation anywhere along the lining of your digestive tract, and often spreads deep into affected tissues. This can lead to abdominal pain, severe diarrhea and even malnutrition. The inflammation caused by Crohn’s disease can involve different areas of the digestive tract in different people.

Collagenous colitis (kuh-LAJ-uh-nus) and lymphocytic colitis also are considered inflammatory bowel diseases, but are usually regarded separately from classic inflammatory bowel disease.

Inflammatory bowel disease symptoms vary, depending on the severity of inflammation and where it occurs.

Ulcerative colitis symptoms
Ulcerative colitis is classified according to its signs and symptoms:

Ulcerative proctitis. In this form of ulcerative colitis, inflammation is confined to the area closest to the anus (rectum), and for some people, rectal bleeding may be the only sign of the disease. Others may have rectal pain, a feeling of urgency or have frequent, small bowel movements. This form of ulcerative colitis tends to be the mildest.
Proctosigmoiditis. This form involves the rectum and the lower end of the colon, known as the sigmoid colon. Bloody diarrhea, abdominal cramps and pain, and an inability to move the bowels in spite of the urge to do so (tenesmus) are common problems associated with this form of the disease.
Left-sided colitis. As the name suggests, inflammation extends from the rectum up through the sigmoid and descending colon, which are located in the upper left part of the abdomen. Signs and symptoms include bloody diarrhea, abdominal cramping and pain on the left side, and unintended weight loss.
Pancolitis. Affecting more than the left colon and often the entire colon, pancolitis causes bouts of bloody diarrhea that may be severe, abdominal cramps and pain, fatigue, and significant weight loss.
Fulminant colitis. This rare, life-threatening form of colitis affects the entire colon and causes severe pain, profuse diarrhea and, sometimes, dehydration and shock. People with fulminant colitis are at risk of serious complications, including colon rupture and toxic megacolon, a condition that causes the colon to rapidly expand.
The course of ulcerative colitis varies, with periods of acute illness often alternating with periods of remission. Most people with a milder condition, such as ulcerative proctitis, won’t go on to develop more-severe signs and symptoms.

Crohn’s disease symptoms
Inflammation of Crohn’s disease may involve different parts of the digestive tract in different people. The most common areas affected by Crohn’s disease are the last part of the small intestine called the ileum and the colon. Inflammation may be confined to the bowel wall, which can lead to scarring (stenosis), or inflammation may spread through the bowel wall (fistula).

Signs and symptoms of Crohn’s disease can range from mild to severe and may develop gradually or come on suddenly, without warning. Signs and symptoms may include:

Diarrhea. The inflammation that occurs in Crohn’s disease causes cells in the affected areas of your intestine to secrete large amounts of water and salt. Because the colon can’t completely absorb this excess fluid, you develop diarrhea. Intensified intestinal cramping also can contribute to loose stools. Diarrhea is a common problem for people with Crohn’s.
Abdominal pain and cramping. Inflammation and ulceration may cause the walls of portions of your bowel to swell and eventually thicken with scar tissue. This affects the normal movement of contents through your digestive tract and may lead to pain and cramping. Mild Crohn’s disease usually causes slight to moderate intestinal discomfort, but in more-serious cases, the pain may be severe and include nausea and vomiting.
Blood in your stool. Food moving through your digestive tract may cause inflamed tissue to bleed, or your bowel may also bleed on its own. You might notice bright red blood in the toilet bowl or darker blood mixed with your stool. You can also have bleeding you don’t see (occult blood).
Ulcers. Crohn’s disease and ulcerative colitis can cause small sores on the surface of the intestine that eventually become large ulcers that penetrate deep into — and sometimes through — the intestinal walls. You may also have ulcers elsewhere, including in your mouth similar to canker sores.
Reduced appetite and weight loss. Abdominal pain and cramping and inflammation of your bowel wall can affect both your appetite and your ability to digest and absorb food.
People with severe Crohn’s disease may also experience:

Fever
Fatigue
Arthritis
Eye inflammation
Skin disorders
Inflammation of the liver or bile ducts
Delayed growth or sexual development, in children
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.

No one is quite sure what triggers inflammatory bowel disease, but there’s a consensus as to what doesn’t. Researchers no longer believe that diet and stress are main causes, although stress can often aggravate symptoms. Instead, current thinking focuses on the:

Immune system. Some scientists think a virus or bacterium may trigger IBD. The digestive tract becomes inflamed when your immune system tries to fight off the invading microorganism (pathogen). It’s also possible that inflammation may stem from an autoimmune reaction in which your body mounts an immune response even though no pathogen is present.
Heredity. Because you’re more likely to develop IBD if you have a parent or sibling with the disease, scientists suspect that genetic makeup may play a role. However, most people who have IBD don’t have a family history of the disorder.