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We do not know the exact cause of ulcerative colitis. However, research suggests that abnormal immune system responses play a role. Inflammation is your body's natural response to injury, irritation and infection. Normally, inflammation is a temporary reaction. If you have ulcerative colitis, your immune system doesn't know when to turn the inflammation off.
Other Causes of Ulcerative Colitis
Other possible causes include:
Bacteria that produce toxins and irritate the lining of your colon
Food sensitivity, which can cause symptoms when you eat trigger foods, such as dairy and gluten
Genetic factors, which can be passed down from one generation to another
Medications, including aspirin and ibuprofen, which can irritate the lining of your colon
Severe reactions to antibiotics
Other gastrointestinal conditions, such as malabsorption of acids made by the liver (bile acid), which can damage the lining of your colon