14 Common Causes of Canker Sores

People commonly mistake a canker sore for a cold sore or fever blister. Cold sores are infections that come from the herpes virus. A cold sore is contagious. A canker sore is not contagious. There are three types of canker sores a person may suffer from.

A minor sore is the most common type of canker sore and will last about two weeks. The lesions are quite small. A major sore is deeper than a minor sore and will be larger than 10 mm in size. A major canker sore may take months to heal and may leave a scar.

Herpetiform sores are large groups of several canker sores. There can be up to 100 ulcers at the same time. This type of canker sore often will heal without any scarring. Multiple factors may lead to a canker sore appearing. Here are 14 common causes of canker sores. 


1. Injury

If you get hit in your mouth or receive any type of injury to your mouth, it may cause a canker sore to appear. You may notice a small canker sore after you have any dental work done. This could include getting dentures or braces placed in your mouth. You may also simply brush your teeth too hard, which could lead to a canker sore developing.

When you are brushing, make sure that you are gentle, especially around your lips. You should be brushing at least twice each day to make sure that you do not develop any other issues with your teeth. However, if you have a canker sore around your mouth, you may want to switch to a softer bristle brush and be a bit more gentle while brushing. Canker sores caused by a mouth injury will typically be small and should go away within a couple of weeks.