What Causes Mouth Sores?

There are several different kinds of mouth sores, and many individuals experience some type of sore at least once throughout their lives. Mouth sores can develop on or around any soft tissues that make up the mouth, including the roof, floor, tongue, gums, cheeks, and lips. It's also possible to develop sores on the esophagus, which is the tube that connects an individual's mouth to their stomach. The majority of mouth sores are minor irritations that last for just one or two weeks.