What Happens

Crohn's disease is an ongoing (chronic) condition that may flare up throughout your life. The course of the disease varies greatly from one person to another. Some people may have only mild symptoms, while others may have severe symptoms or complications that, in unusual cases, may be life-threatening.

Crohn's disease may be mild, moderate, severe, or not active (in remission). It may be defined by the part of the digestive tract involved, such as the rectum and anus (perianal disease) or the area where the small intestine joins the large intestine (ileocecal disease). Some people may have features of both Crohn's disease and ulcerative colitis, the other major type of inflammatory bowel disease (IBD).

Crohn's disease can cause complications outside the digestive tract, such as joint pain, eye problems, a skin rash, or liver disease, suggesting a possible immune system response.

Because Crohn's disease can cause inflammation in parts of the intestines that absorb nutrients from food, it can cause deficiencies in vitamin B12, folic acid, or other nutrients. The disease can increase the risk of gallstones, kidney stones, and certain uncommon forms of anemia.

In long-term Crohn's disease, scar tissue may replace some of the inflamed or ulcerated intestines, forming blockages (bowel obstructions) or narrowed areas (strictures) that can prevent stool from passing through the intestines. Blockages in the intestines also can be caused by inflammation and swelling, which may improve with medicines. Sometimes blockages can only be treated with surgery.

If sores break through the wall of the intestines, abnormal connections or openings (fistulas) may develop between two parts of the intestines, between the intestines and other organs (such as the bladder or vagina), or between the intestines and the skin. In rare cases, this can lead to infection of the abdominal wall.

Crohn's disease of the colon and rectum that has been present for 8 to 10 years or longer increases the risk of cancer. But the risk of colorectal cancer may be higher with ulcerative colitis than with Crohn's disease. With regular screening, some cancers can be detected early and treated successfully.

Most women who have Crohn's disease are able to become pregnant and have healthy babies. Symptoms may become worse during the first 3 months of pregnancy. Some medicines used to treat the disease can be used during pregnancy.