Follow-Up:
I have had canker sores my whole life. My pediatrician (who I still see at parties etc.) now believes that they are a strain of virus related to herpes (don't panic though, he added, it's allegedly not contagious). I have tried everything from peroxide to iodine. The two things that work best are 1) Alum--ask pharmacist for "powdered alum", but "lump alum" will also work. Place on affected area ONLY & do not swallow for full minute. Rinse mouth well with water. This stuff is more sour than 1000 lemons, so try to keep it as localized & in as small amount as possible. Do not swallow this stuff, aside from the natural bit of trickle that "gets away". It is a styptic as used for shaving cuts. 2) "Tea tree oil". This seems to work the best & tastes slightly better than alum. My dentist says it's against the law for him to recommend it, since it's not FDA approved, so that would explain why professionals won't suggest it. It is available in every health food store. If not, they can order it. It may also be listed as "Australian Tea Tree Oil". Dip swab in the oil, place on sore for 1-2 minutes, spit frequently afterwards but don't rinse right away. This has similar properties to the alum, but not as offensive. I use the pure oil full strength, but there are other products that "contain" the oil. These I consider to be too diluted. I use both twice a day till sores dissapate (usually within 12-24 hours). I assume no responsibility for these suggestions, but I list them here, for they are the only things that work for me. (My lame disclaimer). Tea tree is one of those "natural" medicines that I do NOT consider to be quackery.