How do docs treat a canker sore on tonsils?

Canker sore: There is not much to do, salt ANS water garggling soothes it, it should resolve on its own.

Not sure: Some find that applying table salt on the sores may help (painful when applied), others have tried topical antibiotic with success. Still others have been treated with a topical cortisone paste. All of which work for some people. There is no sure cure since we do not know what causes canker sores yet.