Q: What are canker sores? A: Canker sores are small shallow ulcers that appear in the mouth and often make eating and speaking uncomfortable. The exact cause of most canker sores is unknown; however stress, tissue injury, and certain acidic fruits or vegetables (ex: lemons, oranges, pineapples, apples, figs, tomatoes, strawberries, etc.) can trigger or worsen a canker sore. Oftentimes, a sharp tooth surface or dental appliance, such as braces or ill-fitting dentures, might also trigger canker sores. Studies have shown that certain canker sores can be caused by underlying health conditions such as an impaired immune system, nutritional problems (ex: vitamin B-12, zinc, folic acid, or iron deficiencies), or gastrointestinal tract diseases. (ex: Celiac disease and Crohn’s disease.) Canker sores typically heal within 2 weeks. You should contact your dentist if you have a sore that last longer than 2 weeks or if you have unusually large sores, sores that are spreading, or difficulty drinking enough fluids. Q: Are cold sores another name for canker sores? A: No. Although these sores are often confused for each other, they are not the same. Cold sores (also called fever blisters) are groups of painful, fluid-filled blisters. Unlike canker sores, cold sores are caused by the herpes simplex virus which is extremely contagious. Also, cold sores typically appear outside the mouth (usually around the lips) while canker sores occur inside the mouth. To prevent cold sores, people should avoid contact with infected people. Cold sores are extremely common., cold temperature, ultraviolet sunlight, sunburn, emotional stress, nerve injury, or abrasions can reactivate the herpes simplex virus to cause cold sores. There are antiviral medications that can be prescribed by your dentist to help to limit both the severity and duration of a cold sore provided it is applied early enough (i.e., at the tingle stage). These medications do not provide a cure for cold sores nor are they considered preventive in nature. Even after the use of the medication and after the cold sore has healed,the herpes virus still resides latently within the person's body therefore the person still retains their potential for future cold sore outbreaks.