In their paper, published in August 2010, the researchers concluded that "Tetracycline class antibiotics, and particularly doxycycline use may be associated with the development of IBD, particularly Chron's Disease (CD). Potential confounding by previous doxycycline exposure should be considered when Crohn's whether treatment with other acne medications increases the risk of IBD."
Inflammatory bowel disease refers to a group of inflammatory conditions that occur in the colon and small intestine. The two main types of inflammatory bowel disease are Crohn's disease and ulcerative colitis. Some patients who developed IBD required surgery to remove a section of their colon or even their entire colon.