Canker sores are painful areas of ulceration along the delicate inner mucosa of the mouth. The exact causes of canker sores are not clearly understood, but they seem to be linked to genetics, oral trauma, and dietary deficiency. Usually, canker sores will go away on their own after a short period of time, but if they are spreading or painful, a doctor may prescribe topical medication to help reduce the pain and shrink the canker sores. Canker sores are also sometimes referred to as aphthous ulcers.

There is no evidence to indicate that this is an infection due to a virus or other microorganism. Damage to the tissue inside the mouth, such as biting the inside of the cheek, may cause an ulcer in susceptible people. Ulcers in the mouth can occur for many reasons other than canker sores. A doctor can diagnose cankers based on a history of recurring ulcers in the mouth if no other condition is identified that can be causing the ulcers. The history of ulcers will usually start in childhood or early adulthood.

When canker sores appear, it can be quite painful. Many people treat canker sores at home by taking aspirin to reduce the pain, or applying topical analgesic gels directly to the sore. In addition, if you have an active canker sore, you should avoid eating acidic foods and chocolate, which can aggravate the canker sore. Heavily salted and crunchy foods may also be unpleasant to eat. Some foods, like pineapples and mangos, also contain enzymes which can irritate a canker sore.

If you have canker sores, avoid abrasive foods such as potato chips that can stick in the cheek or gum and aggravate the sores. Take care when brushing your teeth not to stab the gums or cheek with a toothbrush bristle. Avoid acidic and spicy foods.