text: Unfortunately there is not a way to get rid of mouth ulcers very quickly.  They hurt no doubt.  Swishing with warm salt water several times a day will help with the soreness.  Don't eat anything acidic or spicy. Stay with bland foods for several days.  You can even put a wet tea bag on it for several minutes, this will sooth it.  I would not use Listerine, as it contains a high amount of alcohol and will only sting your mouth like crazy. You can take some Tylenol or Advil to help ease some of the discomfort.  The research is still out as to what causes "canker sores" which is different then cold sores.  It is a given that people seem to get them in higher times of stress, or when you have been eating really spicy foods.  Just be gentle in your home care, and it should resolve in about eight days.  If not ask your dentist/hygienist if there is anything else you can do.