In some people with Crohn's disease, only the last segment of the small intestine (ileum) is affected. In others, the disease is confined to the colon (part of the large intestine). The most common areas affected by Crohn's disease are the last part of the small intestine and the colon.
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, signs and symptoms may include:
- 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 also may experience:
- Inflammation of skin, eyes and joints
- Inflammation of the liver or bile ducts
- 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
- Ongoing bouts of diarrhea that don't respond to over-the-counter (OTC) medications
- Unexplained fever lasting more than a day or two
- Unexplained weight loss
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. A number of factors, such as heredity and a malfunctioning immune system, likely play a role in its development.
- Immune system. It's possible that a virus or bacterium may trigger Crohn's disease. When your immune system tries to fight off the invading microorganism, an abnormal immune response causes the immune system to attack the cells in the digestive tract, too.
- Heredity. Crohn's is more common in people who have family members with the disease, so genes may play a role in making people more susceptible. However, most people with Crohn's disease don't have a family history of the disease.
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 and people of Eastern European (Ashkenazi) Jewish descent have the highest risk. However, the incidence of Crohn's disease is increasing among blacks who live in North America and the United Kingdom.
- Family history. You're at higher risk if you have a close 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 (Voltaren) and others. While they do not cause Crohn's disase, they can lead to inflammation of the bowel that makes Crohn's disease worse.
- Where you live. If you live in an urban area or in an industrialized country, you're more likely to develop Crohn's disease. This suggests that environmental factors, including a diet high in fat or refined foods, may play a role in Crohn's disease.
Crohn's disease may lead to one or more of the following complications:
- Bowel obstruction. Crohn's disease affects the thickness of the intestinal wall. Over time, parts of the bowel can scar and narrow, which may block the flow of digestive contents. You may require surgery 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 skin, or between your intestine and another organ. Fistulas near or around the anal area (perianal) are the most common kind.
When fistulas develop in the abdomen, food may bypass areas of the bowel that are necessary for absorption. Fistulas may occur between loops of bowel, into the bladder or vagina, or out through the skin, causing continuous drainage of bowel contents to your skin.
In some cases, a fistula may become infected and form an abscess, which can be life-threatening if not treated.
- 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 every 10 years beginning at age 50. Ask your doctor whether you need to have this test done sooner and more frequently.
- Other health problems. Crohn's disease can cause problems in other parts of the body. Among these problems are anemia, skin disorders, 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 risk of infection.
Corticosteroids can be associated with a risk of osteoporosis, bone fractures, cataracts, glaucoma, diabetes and high blood pressure, among others. Work with your doctor to determine risks and benefits of medications.