A natural home remedy for getting rid of a canker sore is to take some warm water and mix in some salt and stir it up.
Then gargle with the warm salt water and continue to gargle with the salt water at least twice per day until the canker sore is gone.
Another way of getting rid of a canker sore in your mouth is to put a numbing agent or baby orajel on the canker sore.
The canker sore should then go away within a few days but it can take a week for the canker sore to go away without treatment.