What is Crohn's disease? A Mayo Clinic expert explains

Learn more about Crohn's disease from gastroenterologist William Faubion, M.D.

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William A. Faubion, Jr., M.D., Gastroenterology, Mayo Clinic: I'm Dr. Bill Faubion, a gastroenterologist at Mayo Clinic. In this video, we'll cover the basics of Crohn's disease. What it is? Who gets it? The symptoms, diagnosis and treatment. Whether you're looking for answers for yourself or someone you love, we're here to give you the best information available. Crohn's disease is an inflammatory bowel disease that causes chronic inflammation of the GI tract, which extends from your stomach all the way down to your anus. Different areas of the GI tract can be affected in different people, and it often spreads into the deeper layers of the bowel. It's estimated that over half a million Americans are living with Crohn's disease. It can be painful and debilitating, occasionally leading to severe complications, as well as emotionally stressful. And while there is no cure, once you've been diagnosed, treatment can help you get back to a more normal and comfortable life.

Who gets it?

There are a lot of particulars that figure into or aggravate Crohn's disease, but the exact cause is still unknown. It may involve an abnormal immune response against some microorganism in which your tissues are also attacked. Genetics might also play a role. And it's true that you're at higher risk if a first-degree relative has it. But that's really only seen in about 20% of cases. There is a correlation with age. Although it can show up at any stage of life, most people are diagnosed before 30. Ethnicity is a risk factor. Whites have the highest risk, especially among people of Ashkenazi Jewish descent. However, incidence is increasing among black people in North America and the UK. Non-steroidal anti-inflammatory medications or NSAIDS... they don't cause Crohn's disease, but they are known to trigger inflammation of the bowel and make it worse. They include common over-the-counter painkillers like ibuprofen, naproxen sodium, diclofenac sodium, and others. So if you've been diagnosed with Crohn's, make sure you talk to your doctor about what medications should be avoided. Many of these elements are out of our hands, but smoking is the most important controllable risk factor for developing Crohn's disease. It also leads to more severe disease and increased need for surgery. So if you smoke and you're diagnosed, now is a good time to quit.

What are the symptoms?

Crohn's disease can affect any area in the GI tract, but it's mostly found in the large and the small intestine. It can also be confined to one area or found in multiple segments. Symptoms can range in severity and it can depend on the area of the GI tract that's affected. You also may experience periods of remission when you have no symptoms or issues at all. The symptoms can come on gradually, but they can also show up suddenly. And these can include diarrhea, fever, fatigue, abdominal pain and cramping, blood in your stool, mouth sores, reduced appetite and weight loss. If your Crohn's disease has caused fistulas or inflamed tunnels in the skin near the anal area, you may notice pain or drainage. And in more severe cases, you may have inflammation of the eyes, skin, joints, liver or bile ducts, kidney stones, and anemia. In children, it can delay growth and development. Over time, Crohn's disease can lead to other complications, including bowel obstruction, ulcers, fistulas, anal fissures, malnutrition, and other health problems. It can also increase your risk for blood clots and colon cancer. Having these symptoms doesn't automatically mean you have Crohn's. But if you're experiencing anything that concerns you, it's a good idea to make an appointment with your doctor.

How is it diagnosed?

There's no single test for Crohn's disease, and it has similar symptoms to a lot of other conditions, so it can take a little time to get a diagnosis. First, your doctor is going to consider your medical history. Then your doctor may want to run a variety of tests or procedures. And at some point, your general practitioner may want to refer you to a specialist called a gastroenterologist like myself. A blood test can check for anemia and check for signs of infection. A stool study can test if there's blood present or rule out certain pathogens. A colonoscopy may be needed. This also allows your doctor to view your entire colon and the very end of the ileum using an endoscope, a small camera mounted on a thin flexible tube. They can take tissue samples for a biopsy at the same time. And the presence of granulomas or clusters of inflammatory cells, can essentially confirm the diagnosis. A CT scan might be ordered for a better look at the bowel and all of the surrounding tissues; or an MRI, which is especially good for evaluating fistulas around the anus or the small intestine. A capsule endoscopy can be done. Here you actually swallow the camera about the size of a large vitamin and it takes images of your digestive tract as it travels through. And a balloon-assisted enteroscopy may be done to get further into the bowel than a standard endoscope can if abnormalities have been found that need further investigation.

How is it treated?

Your doctor can work with you to find therapies that alleviate your symptoms. One of the main goals is to reduce the inflammation that produces painful and disruptive issues. Another is to limit complications over the long-term. There is currently no cure, but many treatments can provide a lot of relief, and in some cases, even long-term remission. These may include anti-inflammatory drugs like corticosteroids, immune system suppressants, and antibiotics. Certain biologics, which target proteins made by the immune system, can help. Antidiarrheals, pain relievers, and supplements can help counter other symptoms. Nutritional therapy and a special diet may be recommended. And in some cases where other measures aren't effective, surgery may be required. And that's to remove the damaged tissue. Some of these therapies may have side effects themselves. So be sure and review the risks and benefits with your doctor.

What now?

Crohn's disease can be physically and emotionally challenging, but there are things that can help. Although there's no firm evidence that any particular foods cause Crohn's disease, certain things seem to aggravate flare-ups. So a food diary can help you identify personal triggers. Beyond that, limit dairy products, eating smaller meals, stay hydrated, and try to avoid caffeine, alcohol, and carbonation. Consider multivitamins if you're concerned about weight loss. Or if your diet has become too limited, talk to a registered dietitian. And again, if you smoke, you should stop. It's important to take care of your mental health too. Find ways to manage stress, like exercise, breathing, relaxation techniques or biofeedback. Some symptoms like abdominal pain, gas, and diarrhea... they can cause anxiety and frustration. They can make it difficult to go out in public for any amount of time. It can feel limiting and isolating and lead to depression. So learn as much as you can about Crohn's. Staying informed can help a lot in feeling like you're in control of your condition. Talk to a therapist, especially one familiar with inflammatory bowel disease. Your doctor can give you some recommendations. And you might want to find a support group of people going through the same thing that you are. Crohn's disease is a complex disease. But having expert medical care and developing a treatment strategy can make it more manageable and even help you get back to the freedom of your normal life. Meanwhile, significant advances continue to be made in understanding and treating the disease, getting us closer to curing it or preventing it entirely. If you'd like to learn more about Crohn's disease, here are other related videos or visit mayoclinic.org. We wish you well.

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Crohn's disease is a type of inflammatory bowel disease (IBD). It causes swelling of the tissues (inflammation) in 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, most commonly the small intestine. 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.

There's no known cure for Crohn's disease, but 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.


In Crohn's disease, any part of your small or large intestine can be involved. It may involve multiple segments, or it may be continuous. In some people, the disease is only in 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, symptoms typically include:

  • Diarrhea
  • Fever
  • Fatigue
  • 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 symptoms outside of the intestinal tract, including:

  • 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
  • Diarrhea lasting more than two weeks
  • Unexplained weight loss
  • Fever in addition to any of the above symptoms

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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 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 an invading microorganism or environmental triggers, an atypical immune response causes the immune system to attack the cells in the digestive tract, too.
  • Heredity. Crohn's disease is more common in people who have family members with the disease, so genes may play a role in making people more likely to have it. However, most people with Crohn's disease do not have a family history of the disease.

Risk factors

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. Crohn's disease is also being increasingly seen in the Middle Eastern population and among migrants to the United States.
  • 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, often known as a stricture. You may require surgery to widen the stricture or sometimes 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 inside the abdomen, it may lead to infections and abscesses, which are collections of pus. These 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 your 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 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 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 8 years after disease onset and generally is performed every 1 to 2 years afterward. Ask your doctor whether you need to have this test done sooner and more frequently.
  • Skin disorders. Many people with Crohn's disease may also 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.
  • Other health problems. Crohn's disease can also cause problems in other parts of the body. Among these problems are low iron (anemia), 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 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 your doctor to determine risks and benefits of medications.

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

Aug. 06, 2022
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