Canker sores are also known as mouth ulcers. They are small, painful open sores on the inside of the mouth that have yellow-gray centers and a red border. They occur on inside of the mouth: the inner side of the lips, the tongue, the back and floor of the mouth and the wall of the cheeks. They do not occur on the lips, the gums or the hard roof of the mouth. The sores can be single or can occur in clusters. 

WHAT CAUSES CANKER SORES?

• human herpes virus 6 (like chicken pox). You would never get a cold sore unless you’ve first had a virus infection, such as measles or chickenpox. This is called the primary infection and it usually occurs when you’re a child or young adult.
• food sensitivities
• stress
• nutrient deficiencies

They generally heal in one to two weeks and may recur monthly or several times per year.

WARNING: Sometimes sores that seem to be canker sores are actually something more serious resulting from drug allergies, herpes infection, inflammatory bowel disease, or cancer. These should not be treated with any home remedy but must be referred to a doctor for care.

HOW DO YOU KNOW IT ISN’T SERIOUS? Simple - left alone, canker sores will get better, and disappear in a week of so. The more serious situations linger. While the size may change they don't get better on their own.

Seven Things You Can Do To Treat Canker Sores