Crohn's disease is a long-term condition that causes inflammation — swelling and irritation — inside your digestive tract. It can affect any part of the tract, from your mouth to your anus, but it most often involves your small intestine. Researchers think an abnormal immune reaction, where the immune system attacks bacteria in the intestines, drives this inflammation. Common symptoms include diarrhea, cramping and pain in your belly, and weight loss. You may also have fatigue, fever, joint pain, anemia, or changes in your skin and eyes. When symptoms flare up, it is called a flare; when they ease, it is called remission. Over time, the disease can lead to complications such as intestinal blockages, fistulas (abnormal tunnels between organs), or malnutrition. There is no cure, but treatments can reduce inflammation, ease symptoms, and help prevent complications. Your care team can work with you to find a plan that fits your needs.