Crohn’s disease is a type of inflammatory bowel disease (IBD) in which an abnormal immune system response causes chronic inflammation in the digestive tract. This can lead to:

  • abdominal pain
  • severe diarrhea
  • fatigue
  • cramping
  • weight loss
  • malnutrition

Crohn’s is often confused with ulcerative colitis, a similar IBD that only affects the large intestine.

In 2015, an estimated 3.1 million adults in the United States had received a diagnosis of IBD, and according to the Crohn’s & Colitis Foundation, Crohn’s disease may affect as many as 780,000 Americans.

During the years 2003 to 2013, there was no significant change in the hospitalization rate when Crohn’s disease was the primary diagnosis. The hospitalization rate, however, increased significantly during this period when Crohn’s disease was the secondary diagnosis, rising from more than 120,000 hospital stays in 2003 to more than 196,000 in 2013.

Anyone can develop Crohn’s disease or ulcerative colitis. IBDs, however, are usually diagnosed in young adults between the ages of 15 and 35.

Children are twice as likely to be diagnosed with Crohn’s as ulcerative colitis. Boys develop IBDs at a slightly higher rate than girls.

In the United States, ulcerative colitis is slightly more common in males, while Crohn’s disease is more frequent in females. White people and Ashkenazi Jews develop Crohn’s at a higher rate than other ethnicities.

Canada has the highest incidence of Crohn’s in the world. There are also increased IBD-related hospitalization rates in northern states compared to southern states for both ulcerative colitis and Crohn’s disease.

Risk factors for Crohn’s disease aren’t clearly established, but family history and cigarette smoking could be factors in the development of the disease.

Active smokers are more than twice as likely as nonsmokers to develop Crohn’s disease, and smoking worsens treatment outcomes and increases flares-ups among people with Crohn’s disease.

One cause of Crohn’s disease may be an autoimmune reaction where the immune system mistakenly attacks healthy bacteria in the GI tract.

Crohn’s most commonly affects the end of the small bowel (the ileum) and the beginning of the colon. That said, it may also affect any part of the GI tract, from the mouth to the anus.

Chronic inflammation causes thickening of the intestinal wall, which triggers the symptoms.

Approximately 20 percent of people with IBD have another family member with IBD, and families frequently share a similar pattern of disease. Between 5 and 20 percent of people with IBD have a first-degree relative with one.

When both parents have inflammatory bowel disease, the risk for their children to develop Crohn’s disease is 35 percent.

There may also be an environmental element. Rates of Crohn’s are higher in developed countries, urban areas, and northern climates.

Stress and diet may worsen Crohn’s, but neither is thought to cause the disease. It’s likely that Crohn’s is caused by a combination of factors.

Symptoms of the disease vary from person to person, depending on the type of Crohn’s.

The most widespread form is called ileocolitis, which affects the end of the small intestine (ileum) and the large intestine (the colon). Symptoms include:

  • pain in the lower or middle part
    of the abdomen
  • diarrhea
  • weight loss

Ileitis affects only the ileum, but causes the same symptoms.

Gastroduodenal Crohn’s disease manifests in the beginning of the small intestine (duodenum) and the stomach. The main symptoms are loss of appetite, nausea, and vomiting, which can result in loss of weight.

Jejunoileitis, another type of Crohn’s, causes areas of inflammation in the upper part of the small intestine (jejunum). It can cause severe abdominal pain and cramping, especially after eating. Another symptom is diarrhea.

When Crohn’s affects only the colon, it’s called Crohn’s granulomatous colitis. This type of Crohn’s causes diarrhea and rectal bleeding. People may develop abscesses and ulcers in the area of the anus. Other symptoms include joint pain and skin lesions.

Other general symptoms of Crohn’s include fatigue, fever, and night sweats.

Other symptoms include:

  • diarrhea
  • 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)

Some people experience an urgent need to move their bowels. Constipation can also be a problem. Women may have an interruption in their menstrual cycle, while young children may have delayed development.

Most people with Crohn’s have episodes of disease activity followed by remissions. The stress of a flare-up can lead to anxiety and social withdrawal.

There’s no single test that can positively diagnose Crohn’s disease. If you have symptoms, your doctor will probably run a series of tests to rule out other conditions.

Diagnostic testing may include:

  • blood tests to look for infection
    or anemia
  • fecal tests to see if there’s
    blood in your stool
  • capsule endoscopy or
    double-balloon endoscopy, two procedures that allow a better view of the small
  • flexible sigmoidoscopy,
    a procedure that helps your doctor view the last section of your colon
  • colonoscopy to enable doctors to get a good look at the entire length of your
    colon and to remove samples for analysis (biopsy)
  • imaging tests such as computerized
    tomography (CT) or magnetic resonance imaging (MRI) to get detailed pictures of
    the abdominal area and intestinal tract

The presence of inflammatory cells in a colonoscopy can help diagnose Crohn’s.

There’s no cure for Crohn’s and treatment usually involves a combination approach. The goal of medical treatment is to reduce the inflammation that triggers your signs and symptoms.

Immune suppressants can help control your immune system’s inflammatory response. Various medications, including anti-inflammatory drugs, corticosteroids, and antibiotics, can be used to treat individual symptoms.

The Crohn’s & Colitis Foundation estimates that two-thirds to three-quarters of those with Crohn’s disease will have one or more operations in the course of their lifetime. About 30 percent of surgical patients will have a flare-up within 3 years, and 80 percent will have one within 20 years.

Good nutritional decisions are crucial for people with Crohn’s. Dietary modifications, especially during severe flare-ups, can help reduce disease symptoms and replace lost nutrients.

A doctor may recommend that you make changes to your diet such as:

  • avoiding carbonated, or “fizzy”
  • avoiding popcorn, vegetable skins,
    nuts, and other high-fiber foods
  • drinking more liquids
  • eating smaller meals more often
  • keeping a food
    to help identify foods that cause problems

Crohn’s can lead to fissures, or tears, in the lining of the anus. This can cause bleeding and pain.

A common and serious complication is when inflammation and scar tissue block the intestines. Crohn’s can also cause ulcers within the intestines.

Another serious complication is the formation of fistulas, abnormal spaces that connect organs within the body. Fistulas affect about 30 percent of people with Crohn’s disease, according to the Crohn’s & Colitis Foundation. These abnormal passages can often become infected.

Crohn’s disease may also increase the risk of colorectal cancer.

Living with Crohn’s disease also takes an emotional toll. Embarrassment over bathroom issues can interfere with your social life and your career. You may find it helpful to seek counseling or join a support group for people with IBD.

Those with IBD are more likely to have particular chronic health conditions, compared to those without IBD. These include:

  • cardiovascular disease
  • respiratory disease
  • cancer
  • arthritis
  • kidney disease
  • liver disease

Crohn’s is an expensive disease.

In a 2008 review, direct medical costs were $18,022 to $18,932 per patient per year in the United States. The total annual financial burden of IBD in the United States is an estimated $14.6 billion to $31.6 billion.

Costs were higher for people with more severe disease activity. Patients in the top 25 percent averaged $60,582 per year. Those in the top 2 percent averaged more than $300,000 per year.