Are canker sores contagious? Can you get them from kissing?

They're unsightly, they're painful and most people suffer from them off and on: canker sores. These slimy, white, odor-causing blisters can really ruin a party, especially if you're hoping to eat some spicy BBQ or do some smoochin' this Memorial Day. So how about it: Are canker sores contagious? Can you get them from kissing or sharing food?

What canker sores are (and aren't)

First, it's important to know what these sores - also called aphthous ulcers - are, and what causes them. Canker sores occur inside your mouth, usually on the delicate tissues of your gums, tongue or inner cheeks. They start when a small nick, cut or irritated area gets infected by oral bacteria (the same odor-causing germs that are responsible for bad breath).

After a few days, these spots turn into small, white, painful patches. Any irritation - be it spices, tobacco smoke or alcohol-based mouthwashes - can cause searing pain.

Canker sores are not cold sores, which are the small, blister-like ulcers that occur on the outside of your mouth, usually around the lips and under the nose. The latter are caused by a virus and are definitely contagious.

But are canker sores contagious?

They are not. Thankfully, you can't catch canker sores from kissing or sharing food or toothbrushes. However, the Nemours Foundation warns that susceptibility to aphthous ulcers runs in families, so if your parents get them, you probably will too.

To treat them and banish the bad breath they cause, consider using specialty, alcohol-free rinses and oxygenating toothpastes. Also, avoid pastes that contain sodium lauryl sulfate, a detergent that is known to cause canker sores.