A mouth in need of canker sore treatment is not life threatening but it sure can feel like it especially if you take a cold drink of water or try to swallow a cup of hot tea. In fact, anything that comes in contact with the canker sore can seriously irritate it just through the act of rubbing the open sore.
That is why one approach to treating the symptoms of canker sores is to actually cover up the sore with something so that it does not touch anything else in the mouth. Usually this is some form of medicated paste or a syrup that creates a barrier between the canker sore and your mouth surface that protects it from being irritated.
In a pinch you can mix together a bit of Benadryl and a bit of Benylin to make a paste and then put it on the sore. The mixture has the effect of stunning the nerves so that you do not feel the sting of the inflammation as severely as you did before. This is because the mixture acts like a mild topical anesthetic and antihistamine that reduces the swelling of the canker. The mixture will be a little syrupy and a bit of a pink color.
You can mix up this paste in a bowl or shot glass. Be sure to apply it with a something hygienic like a cotton swab. If you apply it with your finger there is no guarantee that you will not spread the infection or make it worse as human hands have a habit of picking up a lot of bacteria.
When applying the Benadryl and Benylin canker sore treatment is sure not to apply too much as you do not want the numbing sensation to drip down your throat and affect your swallowing reflexes.