Mucositis or Mouth Sores Make an Appointment Patient Education Find a Doctor Download Patient Education Mouth sores (mucositis) can be caused by chemotherapy and radiation therapy. These cancer treatments target rapidly dividing cancer cells. The treatments can affect other rapidly dividing cells, such as those in your mucous membranes that line your mouth, throat, esophagus, stomach, intestines, and anus. You may notice discomfort anywhere along your GI tract. Download PDF: Mucositis or Mouth Sores Download PDF: Mucositis or Mouth Sores View more information on Mucositis National Jewish Health authors free downloadable patient education materials to provide you and your family the information and tools to help manage your disease. They include Understanding Booklets, Med Facts, Test Facts, Medication handouts and more. Search Free Education Materials