How are cold sores different from canker sores?
Canker sores are red-ringed white sores that can look similar to cold sores but, unlike cold sores, aren’t contagious. Experts aren’t sure what causes canker sores. Commonly cited culprits include stress, vitamin and mineral deficiencies, injury (like scraping your mouth with your toothbrush or a sharp tortilla chip), and astringent chemicals in foods such as lemons or nuts. They usually disappear within 10 days.
