Whether colitis is serious or not is generally related to the type of colitis, the extent of inflammation, and the duration of the disease. Ulcerative colitis, inflammation involving a large area of intestinal tubes, and recurrent episodes over a long period of time are more serious, and the risk of cancer will be high. Colitis is an inflammation of the colon due to various causes such as bacteria, fungi, autoimmunity, etc. Bacterial, fungal and other infections that cause colitis are generally curable with anti-infective treatment and almost never lead to cancer. Autoimmune-related colitis, such as ulcerative colitis, usually has a chronic course with recurrent episodes in most patients, and the prognosis is worse for those with persistent activity or recurrent episodes. And the longer the course of the disease, the greater the risk of cancer. Patients with colitis should go to the hospital in a timely manner, under the guidance of the doctor’s treatment, and patients with a long course of colitis should be monitored regularly with colonoscopy.