Inflammatory bowel disease (IBD) is a group of disorders that cause chronic inflammation (pain and swelling) in the intestines. The symptoms can come and go and may be mild or severe, and they may appear suddenly or come on gradually. IBD symptoms include abdominal (belly) pain, diarrhea, gas and bloating, loss of appetite or unexplained weight loss, mucus or blood in stool, upset stomach. You should call your doctor if you experience excess weight loss, extreme abdominal pain or diarrhea, fever or signs of infection, IBD flare, and signs of dehydration.