Canker sores are small lesions or white blisters, surrounded by a red area. They are not contagious, but are often confused with cold sores, caused by infection with the herpes virus, which is contagious.
Canker sores occur only inside the oral cavity, while cold sores generally appear outside it (on the lips).
Canker sores are recurrent and can be minor (small in size), major (larger) or herpetiform (multiple, grouped or in clusters).
Although the exact cause of the cloud is known, some experts believe that it is based on immune system problems or bacterial or viral infections. In addition, factors such as stress, trauma (dental braces), allergies, smoking, iron or vitamin deficiencies, heredity can influence canker sores.