A canker sore is a small, painful lesion that develops inside the mouth. They can typically be found on or under the tongue, inside your cheek or lip, at the base of the gums, or on the soft palate. They consist of white or gray sores with a red border, and are often preceded by tingling or burning sensations. Canker sores are often confused with cold sores, which present around the outside of the mouth or on the lips in small clusters of blisters that burst and then crust over. Cold sores are caused by the herpes simplex virus, and are contagious. Canker sores, on the other hand, are not contagious and will not appear on the outside of your mouth. The exact cause of canker sores is unknown, but there are several factors which may trigger the development canker sore, including: Although canker and cold sores may be painful at first, this discomfort should lessen within the first few days, and the lesion should heal without treatment in 1-2 weeks. If your canker or cold sore is persistent, unusually large, or extremely painful, or if the sores appear to be spreading, our dentist may recommend corticosteroid ointment, an antimicrobial mouth rinse, or a laser treatment. Over-the-counter solutions may also be recommended to reduce pain and irritation. We also recommend that you rinse the mouth with a warm water solution and avoid eating acidic, citrus, or spicy foods that may irritate the ulcer. If you have any questions about cold or canker sore treatment, and to make an appointment with our caring dentist, please contact our office today.