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Crohn's disease is an inflammatory bowel disease (IBD). It causes inflammation of the lining of 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.
The inflammation caused by Crohn's disease often spreads deep into the layers of affected bowel tissue. Crohn's disease can be both painful and debilitating, and sometimes may lead to life-threatening complications.
While there's no known cure for Crohn's disease, therapies can greatly reduce its signs and symptoms and even bring about long-term remission. With treatment, many people with Crohn's disease are able to function well.
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.
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:
- Diarrhea. Diarrhea is a common problem for people with Crohn's disease. Intensified intestinal cramping also can contribute to loose stools.
- Fever and fatigue. Many people with Crohn's disease experience a low-grade fever, likely due to inflammation or infection. You may also feel tired or have low energy.
- Abdominal pain and cramping. Inflammation and ulceration can affect the normal movement of contents through your digestive tract and may lead to pain and cramping. You may experience anything from slight discomfort to severe pain, including nausea and vomiting.
- Blood in your stool. You might notice bright red blood in the toilet bowl or darker blood mixed with your stool. You can also have bleeding you don't see (occult blood).
- Mouth sores. You may have ulcers in your mouth similar to canker sores.
- Reduced appetite and weight loss. Abdominal pain and cramping and the inflammatory reaction in the wall of your bowel can affect both your appetite and your ability to digest and absorb food.
- Perianal disease. You might have 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:
- 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