Canker sores, also called aphthous ulcers, are small, shallow lesions that develop on the soft tissues in your mouth — under your tongue, inside your cheeks or lips, and at the base of your gums. Unlike cold sores, canker sores don't occur on the surface of your lips and aren't contagious. They can be very painful, however, and can make eating and talking difficult.

Canker sores are usually found on the movable parts of the mouth such as the tongue or the inside lining of the lips and cheeks. The ulcers begin as small oval or round reddish swellings that usually burst within a day. The ruptured sores are covered by a thin white or yellow membrane and edged by a red halo. Generally, the sores heal within 2 weeks without scarring. Canker sores range in size from an eighth of an inch wide in mild cases to more than an inch wide in severe cases. Severe canker sores may leave scars.

Cause of Canker Sores

Recurrent canker sores have been associated with inflammatory bowel diseases, such as Crohn disease and ulcerative colitis. In these cases, the development of canker sores may signal a flare-up of the bowel disease.

Canker sores can run in families. They may also be linked to problems with the body's immune (defense) system. The sores may occur after a mouth injury due to dental work, aggressive tooth cleaning, or biting the tongue or cheek

Certain strains of the herpes virus cause cold sores. Herpes simplex virus type 1 usually causes cold sores. Herpes simplex virus type 2 is usually responsible for genital herpes. However, either type of the virus can cause sores in the facial area or on the genitals. You get the first episode of herpes infection from another person who has an active lesion. Shared eating utensils, razors and towels may spread this infection.

Female sex hormones also apparently play a role in causing canker sores. Many women experience bouts of the sores only during certain phases of their menstrual cycles. Additionally, most women experience improvement or remission of their canker sores during pregnancy.

Canker sores are thought to form when, for unexplained reasons, a person's immune system identifies the presence of chemical molecules that it does not recogniz

Treatment of Canker Sores
Nutritional supplements. Your doctor is likely to prescribe a nutritional supplement if you're low in important nutrients, such as folate (folic acid), vitamins B-6, B-12 and zinc.

Pain from a canker sore generally lessens in a few days and the sores usually heal without treatment in about a week or two.

Avoid hot and spicy foods and foods with sharp crunchy edges, such as nacho chips, which can poke into the canker sore.

Topical pastes. Over-the-counter and prescription pastes such as Orabase, triamcinolone acetonide (Kenalog in Orabase), amlexanox (Aphthasol) and fluocinonide (Lidex) can help relieve pain and speed healing if applied to individual lesions as soon as they appear.

Medications: The use of no steroidal anti-inflammatory drugs (NSAIDs), beta blockers, chemotherapeutic agents, and nicorandil have each been reported as possibly acting as a trigger for outbreaks of canker sores.

Avoid acidic foods or beverages such as orange juice. Anything acidic produces a burning sensation when it comes into contact with the sore.

To speed up healing, try mixing 1 part hydrogen peroxide and one part water and apply it to the canker sore with a cotton swab. Then dab a small amount of milk of magnesia on the canker 3-4 times a day. This also helps relieve discomfort.