Gotta get bitchy and pedantic in the morning on someone, sorry
1. Meth is terribly corrosive to teeth and gums
Not really, no. Meth mouth is what happens to poor people in America with or without meth, and homeless and addicts anyway. We used to just call them toothless hillbillies.
Meth is not battery acid, people. There'll be more "acid" in a shot of orange juice. But rinse your mouth and stay hydrated anyway.
Cocaine's an anesthetic or it'd burn your nostrils too.
2. Your cold sores are because when theres a tonne of dopamine flowing around your immune system becomes very weak + lack of nutrition and sleep = compromised immune system
Dopamine has nothing to do with it. (There are also two OTHER neurotransmitters involved everyone forgets about, and being all body-wired is probably all the norepinephrine flowing around). But, yeah, stress can fuck your immune system, activate trasnsposons, latent viral infections.
3. cold sores are caused by a virus, normally takes 2 weeks before the first symptoms of this virus appear
Ok, yeah, except you probably already have the virus, since your were a baby; stress can cause a rapid outbreak, not that OP had cold sores.
4. meth is often cut with god knows what aand can do damage to tissue
Cutters could damage tissue. Although so does mouthwash.
It's the lifestyle more than the drug. And OP was dreaming.