I hate canker sores
The medical term is apthous ulcers and they are round or oval painful ulcers that appear on the tongue, inner lips, side cheeks or palate of the mouth. Up to 40% of people have experienced canker sores. So why have the remaining 60% never had them? We don't know.
They are more common in young people and occur more frequently in white people, non smokers and people with high socioeconomic status. Why? We don't know.
What we do know is that they are not contagious and they are not caused by the herpes virus.
Once a person has had a canker sore they are easy to self-diagnose going forward. Some diseases cause canker sores to coalesce and form larger ulcerations. People with AIDS, Bechets disease and even ulcerative colitis can experience large canker sores that can respond to immune suppressive drugs.
But the average person who has canker sores is advised to take pain medication and wait until it goes away. That can take a week to 10 days. Obviously any mouth sore that does not heal within 2-3 weeks needs to be evaluated by a physician. (See my last post on Michael Douglas's oropharyngeal cancer.)
Full disclosure for this article...I have a canker sore on the hard palate (roof of mouth) right now and I truly hate canker sores.