Lysine takes out cold sores in the mouth (herpes family of viruses, including ones that *aren’t* STDs).
Probably I bought the bottle for that, I’m prone to (REGULAR) cold sores.
I found that prunella or lemon balm extract heal them very fast too. (I make both extracts, tincture em. I can send prunella seeds to anyone, really useful stuff also called self-heal or heal-all.)