This is a chronic inflammatory disease that may affect the lining of the gut from the mouth to the anus (unlike ulcerative colitis which only ever affects the large intestine or rectum). It presents commonly with unintentional weight loss, abdominal pain and diarrhoea. Interestingly, it is more common in cigarette smokers; the disease has a more favourable outcome if smokers stop smoking! Patients with Crohn’s disease may suffer with fistulating disease whereby an abnormal connection develops between two different parts of the intestine, another organ or the skin, for example, a colo-vesical fistula whereby there is an abnormal connection between the colon and bladder. Another unusual feature of Crohn’s disease is that because the disease may involve the whole thickness of the intestinal wall, loops may get “stuck” together leading to an inflammatory mass. This may not respond to treatment with drugs and may need to be removed by a surgeon. Many different drugs may be used to treat Crohn’s disease. My preferences include the early use of mercaptopurine, a special liquid diet (e.g. Modulen IBD), antibiotics (especially for Crohn’s disease affecting the colon or anus), methotrexate (if intolerant to mercaptopurine) or biologics (infliximab or adalimumab).