1500 mg twice daily for the acute oral stoma. In this setting zinc 15 mg twice daily will be helpful as well. Some also benefit from methylfolate and methylcobalamin 1 mg each, taken 2-3 times a day for the same period.
Maintenance doses of lysine can continue at 1500 mg twice daily zinc 15 mg once daily and methylfolate and methylcobalamin can be ongoing as well, if you have recurrent sores, historically, and benefit from this above treatment.
Can be a lack of stomach acid, ironically. It can be that plus an infection, such as h pylori, can be a histamine response as well.
The best way to start is with a digestive enzyme- a gentle middle of the road enzyme called digestzymes by designs for health, comes to mind. If you do not find relief with this- you can take 2 caps of olive leaf extract and then follow with digestzymes (best taken with meals)