Crohn’s and colitis are the two major forms of chronic inflammatory bowel disease, also known by its abbreviation IBD. It is important to not confuse IBD with IBS, or irritable bowel syndrome. Inflammatory Bowel Disease is an abnormal response of the body’s immune system that leads to visible sores (ulcerations) in the lining of the intestine, either in the large intestine or colon (ulcerative colitis) or predominantly in the small intestine (Crohn’s Disease). In Irritable Bowel Syndrome (IBS) no inflammation is present.

Crohn’s disease can affect the small and/or large intestine with areas that are unaffected in between. Ulcerative colitis affects only the colon and the inflammation is continuous. There are other important differences. Ask your gastroenterologist.


Crohn’s disease can affect any part of the gastrointestinal (GI) tract, but ulcerative colitis affects only the colon. Additionally, while Crohn’s disease can affect all layers of the bowel wall anywhere in the entire intestinal tract, ulcerative colitis only affects the lining of the colon.

The most common symptoms of IBD are diarrhea, cramping, blood in the stool, pain in your abdomen, and weight loss. There are a multitude of additional symptoms some patients may experience and it is imperative that you see a gastroenterologist, especially one with an interest in IBD, if you or your primary care provider suspect IBD.

The Crohn’s and Colitis Foundation of America (CCFA) of which Dr. Klaus Gottlieb is a professional member, is an excellent source of information and maintains a directory of IBD specialists.

Dr. Klaus Gottlieb has worked and published with the leading experts in the field; see a partial list below. He has also overseen clinical trials of cutting-edge new biologicals for IBD and was one of the main FDA scientific reviewers for the IBD medication vedolizumab (Entyvio ®). In addition, he has led efforts to improve the accuracy of the assessments of endoscopic disease activity in ulcerative colitis.


Lewis, James D., Lindsey Albenberg, Dale Lee, Mario Kratz, Klaus Gottlieb, and Walter Reinisch. “The importance and challenges of dietary intervention trials for inflammatory bowel disease.” Inflammatory Bowel Diseases 23, no. 2 (2017): 181-191.

Gottlieb, Klaus, Simon Travis, Brian Feagan, Fez Hussain, William J. Sandborn, and Paul Rutgeerts. “Central reading of endoscopy endpoints in inflammatory bowel disease trials.” Inflammatory Bowel Diseases 21, no. 10 (2015): 2475-2482.

Kim, Yoonhee, Andrew E. Mulberg, Jessica J. Lee, Klaus Gottlieb, Freda Cooner, Sue Chih H. Lee, Li Zhang, and Insook Kim. “Su1083 Can Crohn’s Disease Activity Index Differentiate Clinical Remission Induced by Placebo Versus Biologics Treatment?–Analyses of Six Clinical Trials for Crohn’s Disease.” Gastroenterology 146, no. 5 (2014): S-368.

Yoonhee, Kim, Klaus Gottlieb, Li Zhang, Freda Cooner, Jessica Lee, Sue Chih Lee, and Insook Kim. “P-142 Meta-analysis of Baseline C-reactive Protein and Clinical Remission in Nine Crohn’s Disease Clinical Trials.” Inflammatory Bowel Diseases 19 (2013): S80-S81.

Sultan, Mohamed, Walid Chalhoub, Klaus Gottlieb, and Gustavo Marino. “Endosonographic Findings in Colitis Cystica Profunda.” ACG Case Reports Journal 1, no. 3 (2014): 122-123.

Bewernitz, Michael, Christine Garnett, Klaus Gottlieb, Kevin Krudys, Andrew E. Mulberg, Aisha P. Johnson, Anil Rajpal et al. “Assessment of Adalimumab Dose Selection for Adult Ulcerative Colitis Using Exposure-Response Analyses.” JOURNAL OF PHARMACOKINETICS AND PHARMACODYNAMICS 40 (2013): S44-S45.

Gottlieb, Klaus, Lisa Kammermann, Anil Rajpal, Andrew Mulberg, and Donna Griebel. “Modernizing clinical trial design: Could C‐Reactive Protein (CRP) serve as an enrichment biomarker in Crohn’s disease trials?: P‐38.” Inflammatory Bowel Diseases 17 (2011): S23-S24.