How long does an outbreak of aphthous stomatitis (canker sore) last?

Canker sores usually heal on their own after a week or two. They are not contagious, but can return frequently and may be only one canker sore or several.

Their exact cause is uncertain but some experts believe that immune system problems, bacteria or viruses may be involved. 

An outbreak of canker sores, or small mouth ulcers, can last a week or two. Canker sores (also know as aphthous stomatitis)  make eating and talking painful.  Simple canker sores  last about a week and occur in people from 10-20 years old about 3 to 4 times a year. Complex canker sores may last longer and occur more often. They tend to occur in people who've had canker sores before. Talk to your doctor or dentist if you have an outbreak.

Most outbreaks of aphthous stomatitis (canker sore) last 10 days to 2 weeks. At the end of the outbreak, the ulcers heal and disappear without leaving scars. If you still have ulcers after 2 weeks, a doctor or dentist should look at them. You may have an underlying health condition that needs medical attention.