What causes canker sores? Do they lead to bad breath?

If you've ever had a canker sore, it was probably hard to ignore for long. These erosions on the inner membranes of the mouth typically cause pain and can lead to halitosis. What causes them? The sores themselves occur due to bacterial infections, but often an irritant or small cut is what opens the door for such microbial growth.

Toothpastes and mouthwashes containing sodium lauryl sulfate (SLS) or alcohol are an example of something that may irritate your gums, tongue and cheeks excessively. Both substances may lead to inflammation of the delicate tissue in your mouth. If bacteria begin to flourish there, you may develop a canker sore.

Avoiding SLS- and alcohol-based products is an effective way to reduce your risk of these sores, which are also known as aphthous ulcers. A recent article in the British Medical Journal noted that in developed nations, canker sores are the most common condition of the mouth's membranes.

The study estimated that 20 percent of the population has aphthous ulcers at any one time, most of whom are teens.