Different types of sores can appear anywhere in the mouth. Some
of the places mouth sores can occur are: Bottom of the mouth
Mouth sores may be caused by irritation from: A sharp or broken
tooth or poorly fitting dentures Biting your cheek, tongue, or
lip Burning your mouth from hot food or drinks Cold sores are
caused by the herpes simplex virus . They are very contagious.
Usually, you will have tenderness, tingling, or burning before
the actual sore appears. Cold sores usually begin as blisters
and then crust over. The herpes virus can live in your body for
years. It only appears as a mouth sore when something triggers
it, such as: Another illness, especially if there is a fever
Hormone changes (such as menstruation) Canker sores are not
contagious. They may look like a pale or yellow ulcer with a red
outer ring. You may have one, or a group of them. Women seem to
get them more than men. The cause of canker sores is not clear.
It may be due to: A weakness in your immune system (for example,
from the cold or