News | Published September 26, 2012 | Written by James Freije, MD, MPH, FACS

When to be concerned about a mouth sore that is taking a long time to heal

The two most common mouth sores are canker sores and cold sores.

Canker sores are shallow, painful ulcers that develop on the inside of the lips and cheeks, tongue or on the back portion of the roof of the mouth, your soft palate. Canker sores are probably caused by a local immune response to stress or irritation. Acidic foods and digestive problems, such as gluten sensitivity, are also possible causes. Canker sores are not contagious and usually heal in 5 to 10 days.

Cold sores are painful blisters that form on the lips, gums and the bony roof of the mouth, the hard palate. They are caused by the herpes simplex virus (type I) and are very contagious. The blisters rupture, crust over and heal within 7 to 10 days. In severe cases, cold sores can be treated with antiviral medications.

A physician should evaluate any sore that lasts for more than two weeks. Some less common, but more serious, mouth sores, such as leukoplakia, which show up as thick white patches, and mouth cancer, are most curable if treated early.

Leukoplakia is caused by chronic irritation such as a jagged tooth or prolonged tobacco use. In some cases it can progress to mouth cancer. Early mouth cancer can resemble canker sores but do not heal. Risk factors of mouth cancer include tobacco use, excessive alcohol consumption, ill-fitting dentures and human papillomavirus. Approximately 25 percent of patients who develop mouth cancer are nonsmokers.

For more information on mouth sores, visit

This article was originally posted in the June 2011 issue of State College Magazine.

About the Author

James Freije, MD, MPH, FACS

James Freije, MD, MPH, FACS is an otolaryngologist (ear, nose and throat specialist) and head and neck surgeon with Mount Nittany Physician Group. He is on staff at Mount Nittany Medical Center.

Articles by Freije