Colon and rectum
The colon, also called the large intestine, is a long tube-like organ in your abdomen. The colon carries waste to be expelled from the body.
Gastroenterology & GI Surgery Blog
Connect with others and follow the latest advances in treating Crohn's disease and ulcerative colitis on Mayo Clinic Connect.
Crohn's disease is a type of inflammatory bowel disease (IBD). It causes inflammation of your digestive tract, which can lead to abdominal pain, severe diarrhea, fatigue, weight loss and malnutrition.
Inflammation caused by Crohn's disease can involve different areas of the digestive tract in different people. This inflammation often spreads into the deeper layers of the bowel.
Crohn's disease can be both painful and debilitating, and sometimes may lead to life-threatening complications.
While there's no known cure for Crohn's disease, therapies can greatly reduce its signs and symptoms and even bring about long-term remission and healing of inflammation. With treatment, many people with Crohn's disease are able to function well.
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 only the colon.
In Crohn's disease, any part of your small or large intestine can be involved, and it may be continuous or may involve multiple segments. In some people, the disease is confined to the colon, which is part of the large intestine.
Signs and symptoms of Crohn's disease can range from mild to severe. They usually develop gradually, but sometimes will come on suddenly, without warning. You may also have periods of time when you have no signs or symptoms (remission).
When the disease is active, signs and symptoms may include:
- Abdominal pain and cramping
- Blood in your stool
- Mouth sores
- Reduced appetite and weight loss
- Pain or drainage near or around the anus due to inflammation from a tunnel into the skin (fistula)
Other signs and symptoms
People with severe Crohn's disease may also experience:
- Inflammation of skin, eyes and joints
- Inflammation of the liver or bile ducts
- Kidney stones
- Iron deficiency (anemia)
- Delayed growth or sexual development, in children
When to see a doctor
See your doctor if you have persistent changes in your bowel habits or if you have any of the signs and symptoms of Crohn's disease, such as:
- Abdominal pain
- Blood in your stool
- Nausea and vomiting
- Ongoing bouts of diarrhea that don't respond to over-the-counter (OTC) medications
- Unexplained fever lasting more than a day or two
- Unexplained weight loss
The exact cause of Crohn's disease remains unknown. Previously, diet and stress were suspected, but now doctors know that these factors may aggravate, but don't cause, Crohn's disease. Several factors, such as heredity and a malfunctioning immune system, likely play a role in its development.
- Immune system. It's possible that a virus or bacterium may trigger Crohn's disease; however, scientists have yet to identify such a trigger. When your immune system tries to fight off the invading microorganism, an abnormal immune response causes the immune system to attack the cells in the digestive tract, too.
- Heredity. Crohn's is more common in people who have family members with the disease, so genes may play a role in making people more susceptible. However, most people with Crohn's disease don't have a family history of the disease.
Risk factors for Crohn's disease may include:
- Age. Crohn's disease can occur at any age, but you're likely to develop the condition when you're young. Most people who develop Crohn's disease are diagnosed before they're around 30 years old.
- Ethnicity. Although Crohn's disease can affect any ethnic group, whites have the highest risk, especially people of Eastern European (Ashkenazi) Jewish descent. However, the incidence of Crohn's disease is increasing among Black people who live in North America and the United Kingdom.
- Family history. You're at higher risk if you have a first-degree relative, such as a parent, sibling or child, with the disease. As many as 1 in 5 people with Crohn's disease has a family member with the disease.
- Cigarette smoking. Cigarette smoking is the most important controllable risk factor for developing Crohn's disease. Smoking also leads to more-severe disease and a greater risk of having surgery. If you smoke, it's important to stop.
- Nonsteroidal anti-inflammatory medications. These include ibuprofen (Advil, Motrin IB, others), naproxen sodium (Aleve), diclofenac sodium and others. While they do not cause Crohn's disease, they can lead to inflammation of the bowel that makes Crohn's disease worse.
Crohn's disease may lead to one or more of the following complications:
- Bowel obstruction. Crohn's disease can affect the entire thickness of the intestinal wall. Over time, parts of the bowel can scar and narrow, which may block the flow of digestive contents. You may require surgery to remove the diseased portion of your bowel.
- 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 can develop between your intestine and your skin, or between your intestine and another organ. Fistulas near or around the anal area (perianal) are the most common kind.
When fistulas develop in the abdomen, food may bypass areas of the bowel that are necessary for absorption. Fistulas may form between loops of bowel, in the bladder or vagina, or through the skin, causing continuous drainage of bowel contents to your skin.
In some cases, a fistula may become infected and form an abscess, which can be life-threatening if not treated.
- 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.
- 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.
- Colon cancer. Having Crohn's disease that affects your colon increases your risk of colon cancer. General colon cancer screening guidelines for people without Crohn's disease 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.
- Other health problems. Crohn's disease can cause problems in other parts of the body. Among these problems are anemia, skin disorders, osteoporosis, arthritis, and gallbladder or liver disease.
Medication risks. Certain Crohn's disease drugs that act by blocking functions of the immune system are associated with a small risk of developing cancers such as lymphoma and skin cancers. They also increase risk of infection.
Corticosteroids can be associated with a risk of osteoporosis, bone fractures, cataracts, glaucoma, diabetes and high blood pressure, among other conditions. Work with your doctor to determine risks and benefits of medications.
- Blood clots. Crohn's disease increases the risk of blood clots in veins and arteries.
Oct. 13, 2020