Canker sores in the mouth can mean halitosis on the breath

Turn on the television, and you'll notice that many adds for mouthwash tout the benefits of alcohol-based rinses. While these products may temporarily freshen breath, they can also cause unintended side effects including gum irritation and canker sores in your mouth.

This might seem counterintuitive. After all, mouthwash is supposed to clean your mouth and, in theory, make it healthier. So how can a minty rinse cause painful sores on your gums and inside your cheeks?

For the answer to that question, you need to know a little bit about what goes into typical mouthwashes and what doesn't go into specialty breath freshening mouthrinses.

Common mouthwashes rely on alcohol, among other active ingredients, to kill bacteria and freshen breath. The principle behind this mechanism is pretty simple. After all, you use rubbing alcohol to kill germs and prevent them from colonizing cuts and scrapes, so why not use it to rid your mouth of odor-causing microbes?

The primary problem is that alcohol doesn't kill bacteria in the long run. Much like alcohol-based hand sanitizers, common mouthwashes simply eliminate 99 percent of irritating microorganisms, leaving the surviving 1 percent to quickly repopulate.

A secondary problem is that alcohol irritates the sensitive tissues of your palate, as do certain other ingredients, which can lead to canker sores in the mouth. Though they can occasionally be confused with cold sores, canker sores are a unique (and avoidable) problem.

What is the key difference? Canker sores are bacterial infections that occur inside your mouth, while cold sores - also known as fever blisters - are viral outbreaks that appear outside the oral environment, usually on or around the lips.

The National Institutes of Health says that the typical canker sore appears as a small, yellowish or whitish spot on the gums or tongue or the insides of the lips or cheeks. Usually, the speck is surrounded by a red ring of inflamed tissue. Also called an aphthous ulcer, this patch of bacterial infection can be quite painful.

If they last more than a few days, these sores can make eating, drinking or talking nearly unbearable, the Mayo Clinic states. The mouth's tissue is quite delicate - so sensitive, in fact, that minor chemical irritants and even stress can lead to canker sores.

Sodium lauryl sulfide (SLS), an ingredient in many alcohol-based mouthwashes, is one of the prime suspects when it comes to canker sore formation. This chemical appears in common mouthwashes as a surfactant and a detergent.

You read that right. Besides contributing to foaming (that's what a surfactant does), SLS is a detergent, hardly different from any you might use in greater quantities to wash your clothes. It's little wonder that this chemical can cause big problems on the quest for fresh breath.

Studies have shown that SLS irritates the delicate tissue that lines your mouth, giving opportunistic bacteria the chance to begin invading the skin. The result is a painful blister.

By contrast, SLS-free specialty breath freshening mouthrinses can not only neutralize bad breath but soothe canker sores and help them heal. A report published in the journal Periodontology 2000 found that products containing chlorhexidine act as an effective remedy for aphthous ulcers and oral soreness in general.

As you can see, the ingredients in your mouthwash are really quite important! By using an SLS- and alcohol-free rinse, you can sweeten your breath without irritating your palate.

Looking into such mouthwashes is a great first step toward fresh breath, but it isn't the only step. Research has shown that people who practice regular dental care - including flossing often and brushing at least twice a day - are less likely to have halitosis.