4. Vitamin B12
With that in mind then, it should follow that increasing your vitamin B12 through any means should work. And indeed that does seem to be the case! For fast and effective relief from canker sores, try taking a vitamin B12 supplement. This should also help you to avoid getting future canker sores by fortifying you against the causes.
You can alternatively try making a kind of paste or gel from your vitamin B12 supplement and applying it to the area directly. If the problem persists, you should look for other signs of a B12 deficiency such as tingling in your extremities.
If you notice these, you may need to get regular shots from your GP.