Crohn's disease

Overview

Crohn's disease is a type of inflammatory bowel disease (IBD) that causes swelling and irritation of the tissues, called inflammation, in the digestive tract. This can lead to belly pain, severe diarrhea, fatigue, weight loss and malnutrition.

Inflammation caused by Crohn's disease can affect different areas of the digestive tract in different people. Crohn's most commonly affects the end of the small intestine and the beginning of the large intestine. The inflammation often spreads into the deeper layers of the bowel.

Crohn's disease can be both painful and debilitating. Sometimes, it may lead to serious or life-threatening complications.

There's no known cure for Crohn's disease, but therapies can greatly reduce its symptoms and even bring about long-term remission and healing of inflammation. With treatment, many people with Crohn's disease can function well.

Symptoms

Symptoms of Crohn's disease typically include:

• Diarrhea.
• Fever.
• Fatigue.
• Belly pain and cramping.
• Blood in the 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, called a fistula.

Crohn's disease can affect any part of the small or large intestine. It may involve multiple segments, or it may be continuous. It most commonly involves the last part of the small intestine. In some people, the disease is only in the colon or the large intestine.

Symptoms of Crohn's disease can range from mild to severe. They usually develop gradually, but sometimes might come on suddenly, without warning. Someone with Crohn's disease also may have periods of time with no symptoms. This is known as remission.

Other symptoms

People with severe Crohn's disease also may experience symptoms outside of the intestinal tract, including:

• Inflammation of skin, eyes and joints.
• Inflammation of the liver or bile ducts.
• Kidney stones.
• Iron deficiency, called anemia.
• Delayed growth or sexual development, in children.

When to see a doctor

See a healthcare professional if you have ongoing changes in your bowel habits or if you have any symptoms of Crohn's disease, such as:

• Belly pain.
• Blood in the stool.
• Nausea and vomiting.
• Diarrhea lasting more than two weeks.
• Losing weight without trying.
• Fever in addition to any of the above symptoms.

Causes

The exact cause of Crohn's disease remains unknown. Previously, diet and stress were suspected, but now healthcare professionals know that these factors may aggravate, but don't cause, Crohn's disease. Several factors likely play a role in its development.

• Genes. More than 200 genes have been associated with Crohn's disease. However, researchers aren't exactly sure what role they play in the condition. Having one or more of these genes may make someone more likely to get Crohn's disease.
• Immune system. It's possible that bacteria, viruses or other environmental factors may trigger Crohn's disease. For example, certain bacteria in the gut microbiome are suspected to be associated with Crohn's disease, but it is unknown if these bacteria cause Crohn's disease. When the immune system tries to fight off an invading microorganism or environmental triggers, an atypical immune response causes the immune system to attack the cells in the digestive tract, too.

Risk factors

Risk factors for Crohn's disease may include:

• Family history. People with a first-degree relative, such as a parent, sibling or child, are at higher risk to have the disease. As many as 1 in 5 people with Crohn's disease has a family member with the disease.
• Age. Crohn's disease can happen at any age, but it's more common 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, white people 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. Crohn's disease also is being increasingly seen in the Middle Eastern population and among migrants to the United States.
• Cigarette smoking. Cigarette smoking is the most important controllable risk factor for developing Crohn's disease. Smoking also leads to more-serious disease and a greater risk of having surgery. If you smoke, it's important to stop.
• Nonsteroidal anti-inflammatory medicines. 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.

Complications

Crohn's disease may lead to one or more of the following complications:

• Bowel blockage or 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, often known as a stricture. Surgery to widen the stricture or to remove the diseased portion of the bowel may be necessary.
• Ulcers. Ongoing inflammation can lead to open sores called ulcers anywhere in the digestive tract. This can include the mouth, anus and genital area.

• Fistulas. Sometimes ulcers can extend completely through the intestinal wall, creating a connection between different body parts that shouldn't be there. This is known as a fistula. Fistulas can develop between the intestine and the skin, or between the intestine and another organ. Fistulas near or around the anal area are the most common kind.

  When fistulas develop inside the abdomen, it may lead to infections and collections of pus called abscesses. This can be life-threatening if not treated. Fistulas may form between loops of bowel, in the bladder or vagina, or through the skin, causing continuous drainage of bowel contents to the skin.

• 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 stool and may lead to a fistula.
• Malnutrition. Diarrhea, belly pain and cramping may make it difficult to eat or for the intestine to absorb enough nutrients. 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 the colon increases the risk of colon cancer. General colon cancer screening guidelines for people without Crohn's disease call for a colonoscopy at least every 10 years beginning at age 45.

  In people with Crohn's disease affecting a large part of the colon, a colonoscopy to screen for colon cancer is recommended about eight years after disease onset and generally is performed every 1 to 2 years afterward. Ask a healthcare professional whether you need to have this test done sooner and more frequently.

• Skin disorders. Many people with Crohn's disease also may develop a condition called hidradenitis suppurativa. This skin disorder involves deep nodules, tunnels and abscesses in the armpits, groin, under the breasts, and in the perianal or genital area. Some Crohn's disease treatments also increase the risk of skin cancers, so a routine skin examination is recommended.
• Other health problems. Crohn's disease also can cause problems in other parts of the body. Among these problems are low iron, called anemia, osteoporosis, arthritis, kidney stones, eye problems, and gallbladder or liver disease.

• Medicine risks. Certain Crohn's disease medicines that block functions of the immune system are associated with a small risk of developing cancers, including lymphoma and skin cancers. They also increase the risk of infections.

  Corticosteroids can be associated with a risk of osteoporosis, bone fractures, cataracts, glaucoma, diabetes and high blood pressure, among other conditions. Work with a healthcare professional to determine risks and benefits of medicines.

• Blood clots. Crohn's disease increases the risk of blood clots in veins and arteries.