Complications

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 ulcerative colitis or Crohn's disease that affects most of your colon can increase your risk of colon cancer. Screening for cancer begins usually about eight to 10 years after the diagnosis is made. Ask your doctor when and how frequently you need to have this test done.
• 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 scarring 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 B-12 caused by the disease.
• Fistulas. Sometimes inflammation 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.