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Causes of Aphthous Ulcers

Aphthous ulcers, also known as canker sores, are common in children and adults. Aphthous ulcers can occur anywhere inside of the mouth. Women are more affected than men, and at least one in five people develop these ulcers. They seem to appear in children more often than adults, but they can appear at any age and usually go away in 10 to 14 days and can be painful and reoccur frequently.

Types of Aphthous Ulcers

There are three types of aphthous ulcers. Minor ulcers are the most common and are small round or oval sores which are less than 10 mm across. The actual sore may look pale yellow, but the surrounding tissues may be swollen and red. You may have only one ulcer, or up to five at one time. Minor Aphthous ulcers usually last from 7 to 10 days and do not leave scars. This type of ulcer is usually not very painful.

Herpetiform ulcers occur in about 10 percent of cases. Despite the name, they are not associated with the herpes virus. The ulcers are pinhead sized and may appear in clusters. These clusters may join and form irregular shapes of painful ulcers. This type takes a week to two months to clear up and may leave scars.

Causes of Aphthous Ulcers

The exact cause of aphthous ulcers is unknown. They are not an infection and they are not contagious. Certain factors are thought to contribute to their occurrence. Injury from brushing too hard or badly fitting dentures and a lack of B12 and folic acid may contribute to their occurrence. Hormonal changes in women before their periods, food allergies, stress, and anxiety may all be factors which cause these ulcers. Some people may also be genetically inclined to develop aphthous ulcers. Certain medications and medical conditions may also cause aphthous ulcers. People who suffer from coeliac disease, HIV infection, Crohn’s disease, and Behcet’s disease are more prone to mouth ulcers.


Most of the time aphthous ulcers clear up on their own without any treatment. You may want to use a straw to drink with, avoid spicy foods, use a soft toothbrush, and talk to your doctor about any medications which may contribute to their occurrence. Your dentist may recommend a chlorhexidine mouthwash or steroid lozenges if your ulcers are very painful and persistent. A pain killing mouth rinse or gel may also give you some limited relief.

Although painful, aphthous ulcers rarely need medical attention. You should visit your dentist if you experience increased redness or pain. These may be signs of a secondary bacterial infection. Cancer of the mouth may start as ulcers, so it is important to visit your dentist regularly so she can monitor your oral health.

While painful, aphthous ulcers are rarely serious. Call or contact our office today if you are experiencing pain and redness. Dr. Taylor and her staff will be happy to answer your questions and help you find relief from the pain.