Overview

Crohn's disease is a type of inflammatory bowel disease (IBD). It causes irritation and swelling, called inflammation, most often in the digestive tract. This can lead to belly pain, severe diarrhea, fatigue, weight loss and malnutrition. Crohn's disease can be painful and make it hard to go about daily life. Sometimes, it may lead to serious or life-threatening complications.

Symptoms of Crohn's disease often happen in cycles, with periods of active disease and periods with fewer symptoms.

Inflammation caused by Crohn's disease can affect different areas of the digestive tract. It most commonly affects the end of the small intestine and the beginning of the large intestine.

As of yet, there is no cure for Crohn's disease. But therapies can greatly reduce its symptoms and even bring about long-term healing of inflammation. With treatment, most people with Crohn's disease can function well and do the activities that they enjoy.

Symptoms

Symptoms of Crohn's disease can range from mild to severe. They usually develop over time, but they sometimes come on suddenly, without warning. Symptoms include:

  • Diarrhea.
  • Fever.
  • Fatigue.
  • Abdominal 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, skipping sections of the intestine. Or it may be continuous. It most commonly involves the last part of the small intestine, called the terminal ileum. In some people, the disease is only in the colon or the large intestine.

Other symptoms

People with Crohn's disease also may experience symptoms outside of the intestinal tract. These conditions are often referred to as extraintestinal manifestations. They include:

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

Flares and remission

Crohn's disease often follows a pattern of flares and remission. During a flare, symptoms become more active or more severe as inflammation increases.

Certain factors — such as smoking, stress, some medicines and specific foods — may be linked to worsening symptoms or flares in some people. However, these factors do not cause Crohn's disease.

Flares may last for days or weeks and can range from mild to severe. Symptoms such as diarrhea, abdominal pain, fatigue and weight loss may worsen during this time.

Between flares, many people have periods of remission when symptoms are lessened or not present. These cycles can vary over time.

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 1 to 2 weeks.
  • Weight loss that happens without trying.
  • Fever in addition to any of the above symptoms.

Causes

The exact cause of Crohn's disease remains unknown. 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 is suspected that a yet unidentified exposure, infection or environmental factor may trigger an immune response that manifests as Crohn's disease. This may happen in people who are genetically susceptible.

Risk factors

Several factors are associated with an increased risk of developing Crohn's disease, including:

  • Family history. People with a first-degree relative, such as a parent, sibling or child, are at higher risk of having the disease. As many as 1 in 5 people with Crohn's disease have 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 the age of 30.
  • Race and ethnicity. Although Crohn's disease can affect any ethnic group, white people have the highest risk, especially people of Eastern European Jewish descent, also called 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 happening more often in the Middle Eastern population and among migrants to the United States.
  • Cigarette smoking. People who smoke cigarettes are more likely to develop Crohn's disease. Smoking also leads to more-serious disease and a greater risk of needing surgery. If you smoke, it's important to stop.
  • Use of nonsteroidal anti-inflammatory medicines. These include ibuprofen (Advil, Motrin IB, others), naproxen sodium (Aleve), diclofenac sodium and others. They do not cause Crohn's disease. However, they can lead to inflammation of the bowel that makes Crohn's disease worse. They also can lead to symptoms that mimic Crohn's disease inflammation.

Complications

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

Digestive tract 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. This is often known as a stricture. Surgery to widen the stricture or to remove the diseased portion of the bowel may be needed.
  • 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 is not typical. 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, they may cause infections and collections of pus called abscesses. 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 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 linked to painful passage of stool and may lead to a fistula.

  • Colon cancer. Having Crohn's disease that affects more than one-third of the colon increases the risk of colon cancer after approximately eight years of disease.

    If Crohn's disease affects your large intestine, screening often starts 8 to 10 years after diagnosis. It may be repeated every 1 to 5 years depending on the findings. If you also have primary sclerosing cholangitis and colonic disease, screening is recommended every year starting at diagnosis. This is due to an elevated risk of colon cancer. Ask a healthcare professional whether you need to have this test done sooner and more often.

Complications outside the digestive tract

  • Skin conditions. People with Crohn's disease can develop skin issues. The most common are tender bumps, called erythema nodosum, and painful skin ulcers, called pyoderma gangrenosum. Some people also may develop a condition called hidradenitis suppurativa (HS). HS causes deep lumps, tunnels and abscesses in areas such as the armpits and groin, under the breasts, or around the genital or anal area.
  • Other health issues. Crohn's disease also can cause issues in other parts of the body. Among these are low iron, called iron deficiency anemia, osteoporosis, arthritis, kidney stones, eye issues, and gallbladder or liver disease.

Nutrition and medicine-related risks

  • 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.
  • Medicine risks. Certain Crohn's disease medicines that block functions of the immune system are associated with a small risk of getting cancers, including lymphoma, cervical cancer and skin cancers. They also might increase the risk of infections. Work with a healthcare professional to determine risks and benefits of medicines.
By Mayo Clinic Staff