I did a lot of homework and studies are showing the foaming detergent in many toothpastes is harsh enough to cause trauma to the mouth and spur cankers. The ingredient to avoid is Sodium Lauryl Sulfate. Look at your toothpastes. There are very minimal varieties without it. I found Rembrant brand has a "canker sore" toothpaste (also called "gentle"). It even says it on the box it helps heal and prevent cankers. I have very few these days! (painful little suckers!!) Good Luck!
Our family has always taken 1 zinc tablet and canker sores are gone within a day. Also, if you get them often, look into changing your toothpaste.
Take a Q-tip dip it in common rubbing alcohol and place it on the sore directly. Will sting but the sore should be gone by the next morning. The alcohol numbs the irritation. Repeat a few times. Best if done at the start of the irritation.
Lysine cured me - taken regularly as a daily supplement & concentrated doses during a breakout. I used to get them monthly! Now I only get them occasionally (every few years).
Get a regular cold alkaselter tablet, break it into small pieces and set it on a sore for about 15 mins, it will sting pretty bad at first but it numbs. It will be gone the next day if you do it about 2 or 3 times.
Taking L-Lysyne at the first sign of a canker sore at double dose. ie. one in morning on empty stomach and two more before bedtime. This is the only thing that works for me.
At the first sign of the cold sore dab some pepto bismol on the sore. The pepto will make go down and dry it out. And even if one doesnt catch it at the first sign the pepto will dry it out.
My 3 year old daughter had seven canker sores in her mouth all at once. I am not sure what caused them to appear, but I did find a very fast acting remedy. I went to the natural food store and got a tube of homeopathic borax tablets. They are itty bitty and you just follow the dosage. I gave them to her that night before bed and the canker sores were gone the next morning, just like that. Might work for you too.
For a cold sore on the lips or in the mouth, place a Q-tip saturated in vinegar on the cold sore for a few minutes. It will hurt (and possibly bleed) but it will be gone within a day.
I have a friend who had canker sores. Her naturopath recommended that she eliminate all peppers from her diet.(hot, green, red, etc.) Result: no more sores.