Crohn's disease affects an estimated 780,000 people in the United States and may be partly genetic.


What is Crohn’s disease?

Crohn’s disease is one form of inflammatory bowel disease (IBD), a disorder that’s characterized by inflammation in the gastrointestinal (GI) tract. (The other main form of IBD is called ulcerative colitis, which can cause similar symptoms and is sometimes mistaken for Crohn’s.) Although Crohn’s can affect any area in the GI tract, from the mouth to the anus, the inflammation usually occurs in the ileum, or the end of the small intestine.

First described by Burrill B. Crohn, MD, in 1932, Crohn’s disease affects an estimated 780,000 people in the United States. The disorder may be partly genetic: It tends to cluster in families and is also more common in certain ethic groups, like Eastern Europeans.

Crohn’s disease vs. ulcerative colitis

There are two main types of IBD: Crohn’s disease and ulcerative colitis. Both are chronic (i.e., long-term) diseases that cause inflammation in the digestive tract, triggering symptoms like abdominal pain and diarrhea. It’s thought that both forms of IBD are caused, in part, by a combination of genetic and environmental factors. Together, they affect an estimated three million adults in the United States, or 1.3% percent of the population, according to the Centers for Disease Control and Prevention (CDC). But the two conditions also have important differences and need to be treated in varying ways. Here’s how to tell them apart:

Crohn’s Disease

Ulcerative Colitis

Occurs in any part of the GI tract, from the mouth to the anus, but usually affects the ileum, the end of the small intestine

Occurs in the large intestine (colon) and rectum

Appears as patches of inflamed areas

Appears as a continuous stretch of inflammation, often from the rectum into the colon

Extends through multiple (or all) layers of the gastrointestinal wall

Extends to the innermost layer of the colon lining

As many as three in four people with Crohn’s disease may require surgery, in which part of the GI tract will be removed

As many as one in three people will need a colectomy, or the surgical removal of the colon

Affects men and women equally

Affects men and women equally

Diagnosed at any age, usually between the ages of 15 and 35

Diagnosed at any age, usually between the ages of 15 and 30

What causes Crohn’s disease?

Experts aren’t entirely sure what causes IBD, but they suspect that a combination of genetic and environmental factors may be to blame. One of the causes of Crohn’s disease may be a “sensitive” immune system, which mistakes harmless bacteria for dangerous pathogens, triggering long-term inflammation and other GI symptoms.

Genetics are thought to be a culprit as well: People are 5% to 20% more likely to develop Crohn’s disease if one of their close relatives also has the condition; the risk is also higher among people of Eastern European descent, and particularly among Ashkenazi Jews. Recently, scientists have found that people with variations in the NOD2 gene—which is responsible for producing a protein that helps protect the body against viruses and bacteria—are more likely to have a form of Crohn’s that affects the ileum.

Although stress and an unhealthy diet could exacerbate the disease itself, neither will cause Crohn’s. However, because Crohn’s disease is more common in urban areas and developed countries compared to rural areas and underdeveloped countries, researchers believe a person’s environment may be partly to blame too.

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Crohn’s disease symptoms

The signs of Crohn’s disease can overlap with those of other conditions, including not only ulcerative colitis, but other GI disorders like stomach ulcers, pancreatitis, gallbladder disease, and colorectal cancer. The symptoms can affect any part of the GI tract—from the mouth to the anus—although Crohn’s disease most commonly occurs in the end of the small bowel (the ileum). Here are some of the most common Crohn’s disease signs:

  • Diarrhea. One of the most common symptoms of Crohn’s disease is diarrhea, or bouts of loose, watery stools that occur more than a few times each day. (In some cases, the diarrhea can be bloody.) Because our bodies lose more fluid in loose bowel movements than solid ones, diarrhea can cause dehydration.
  • Abdominal pain. The inflammation from Crohn’s disease can trigger cramping and pain in the abdomen, the area between the chest and the groin.
  • Nausea. People with Crohn’s disease can experience nausea, or a queasy feeling in their stomachs that may lead to vomiting.
  • Weight loss. Crohn’s disease can trigger nausea and stomach pain, both of which can cause a loss of appetite. Plus, people might cut back on the amount of food they eat in the hopes of avoiding symptoms like diarrhea.
  • Anemia. The inflammation from Crohn’s disease can cause anemia. Anemia is characterized by a lower-than-average number of red blood cells in the body or a lower-than-average amount of hemoglobin, an iron-packed protein that helps shuttle oxygen from the lungs to the tissue, in the cells themselves. The end result: The blood isn’t providing enough oxygen to the rest of the body, causing breathlessness, fatigue, and more.
  • Skin changes, including nodules. Up to 10% of people with Crohn’s disease will develop skin reactions including erythema nodosum (painful, tender bumps), pyoderma gangrenosum (red bumps that become open sores), and aphthous stomatitis (mouth sores), according to a 2016 study in the United European Gastroenterology Journal.
  • Arthritis. Joint pain is the most common non-gastrointestinal complication of IBD, affecting up to one in four people with the condition, according to the Crohn’s & Colitis Foundation. Three different types of arthritis appear in people with Crohn’s disease of any age: peripheral arthritis (which affects the major joints of the arms and legs), axial arthritis (which affects the lower spine), and ankylosing spondylitis (which also affects the spine but can lead to eye, lung, and heart valve inflammation).

How is Crohn’s disease diagnosed?

There’s no specific Crohn’s disease test, per se. Rather, doctors diagnose the disease by using a combination of lab tests and imaging procedures, including endoscopies and colonoscopies. A blood test can determine whether a person has a low red blood cell count (which could signal anemia) or a high white blood cell count (which could indicate inflammation), while a stool test will help detect inflammation and rule out infections with similar symptoms to Crohn’s disease like C. difficile and E. coli.

Other tests using tiny cameras affixed to long, narrow tubes can help diagnose Crohn’s disease while ruling out ulcerative colitis, diverticulitis, and cancer. These include colonoscopies (in which the tiny camera, or endoscope, is used to examine the rectum, colon, and ileum), an upper GI endoscopy (in which an endoscope is inserted down the esophagus and into the stomach), and a capsule endoscopy (in which a capsule that contains a tiny camera is swallowed, and images of the digestive tract are transmitted to a receiver).

Lastly, doctors can use a CT scan (computed tomography), which can create images of the digestive tract, to diagnose Crohn’s disease and check for possible complications.

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Crohn’s disease treatment

There are many different treatments for Crohn’s disease, including medication and surgery. There’s no one type of treatment that will work for everyone, however; instead, a doctor will take a detailed history of your symptoms and run tests before deciding which option may work best for you. Although there are many types of medications available, up to 75% of people with Crohn’s disease may one day need surgery. Common IBD treatments include:

  • Aminosalicylates (5-ASA). Usually prescribed for people with a mild or moderate type of Crohn’s, these medications—which include sulfasalazine, mesalamine, olsalazine, and balsalazide— work by decreasing inflammation in the lining of the GI tract. Although they aren’t specifically approved by the Food and Drug Administration (FDA) to treat Crohn’s, they can help prevent a flare-up, according to the Crohn’s & Colitis Foundation.
  • Corticosteroids. Prednisone and methylprednisolone help treat the inflammation in moderate or severe Crohn’s disease by helping to suppress the body’s immune system. Because they can trigger both short- and long-term effects, people shouldn’t use them continuously.
  • Immunomodulators. If aminosalicylates and corticosteroids haven’t helped quell the inflammation, doctors may prescribe immunomodulators, including 6-mercaptopurine (6-MP), azathioprine, cyclosporine, and methotrexate. These medications also work by suppressing the immune system and may take several weeks or months to start working.
  • Biologics. For people who haven’t responded to other forms of Crohn’s disease treatment, doctors may prescribe newer medications called biologics, which target certain inflammation-causing proteins in the body. These drugs include adalimumab, certolizumab, and infliximab.
  • Small bowel resection. People with severe Crohn’s or those who develop an obstruction in the small intestine (from, for example, the accumulation of scar tissue) may need to undergo small bowel resection surgery to remove part of the intestine. Doctors can perform this procedure by laparoscopic surgery, which involves making small incisions in the abdomen and removing the problematic area with the help of a tiny camera. They can also perform open surgery, in which one larger incision is made on the abdomen to remove the affected part of the intestine.
  • Subtotal colectomy. Also called a large bowel resection, this surgery is performed in people who have severe Crohn’s, an obstruction, or a fistula (a kind of abnormal “tunnel” or connection between two parts of the body, like the anus and surrounding skin). In these instances, a portion of the large intestine is removed, either by laparoscopic or open surgery.
  • Proctocolectomy and ileostomy. Proctocolectomy surgery removes the entire colon and rectum. Ileostomy is a surgery that creates an opening in the abdomen (called a stoma) from a part of the ileum (the lower part of the small intestine) to the outside of a patient’s body. Waste is then eliminated through the stoma rather than through the anus. A removable ostomy pouch will connect to the stoma to collect stool outside of the body.

Can Crohn’s disease be cured or reversed?

There is no Crohn’s disease cure. However, with the right treatment, people with Crohn’s can experience months or years of remission, which means they experience no symptoms. Medications, which can help prevent the immune system from flaring up, not only help ease the symptoms of Crohn’s disease, but also allow the digestive tract to heal. Surgery also isn’t a cure for Crohn’s disease. Although it can reduce the symptoms and conserve parts of the GI tract, about 30% of people who undergo surgery will see a return of their symptoms within three years, and up to 60% will see a return of their symptoms within 10 years, according to the Crohn’s & Colitis Foundation.

There are also many available treatments for the complications of Crohn’s. For example, some people may develop fistulas, which are treated with antibiotics or surgery, while abscesses can be drained with a needle or during surgery.

Living with Crohn’s disease

Diet can play a role in how a person manages Crohn’s disease. While there is no one type of Crohn’s disease diet—and a food that triggers symptoms in one person may not trigger any in another–there are some general tips for eating wisely with Crohn’s. Experts recommend that people who are living with Crohn’s disease keep a food diary, where they can record what they eat and what types of symptoms they experience afterwards.

To avoid triggering GI symptoms, people with Crohn’s may want to eat smaller meals more frequently and drink more liquids. It may also help to decrease the intake of insoluble fiber, especially during a flare; found in nuts, seeds, and vegetable skins, insoluble fiber can draw water into the gut and cause bloating, gas, and cramping. Other foods to avoid include butter, heavy cream, and carbonated drinks.

Some people also say that a low-FODMAP diet can help relieve these symptoms. FODMAPs (the acronym stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) are certain sugars that are poorly absorbed by some people. FODMAPs can be found in some fruits and veggies, dairy, legumes, and artificial sweeteners, among other sources. Because a low-FODMAP diet can be complex, experts recommend consulting with a dietitian about what you can and cannot eat on the plan. A doctor or dietitian may also recommend supplements for people with Crohn’s disease who aren’t getting enough vitamins and minerals through their diet.