Example.

Poisoning by methyl alcohol.

Ethyl alcohol is ok’ish (the regular stuff), while methyl alcohol can make you blind or dead even in small amounts.

Yes, because if you're a hardcore liver-failure-in-three-years alcoholic, quitting cold turkey will kill you, and if you're in the hospital for some other issue, they will make sure you get some alcohol.

Doctors don't prescribe it to people who aren't already putting away 50 drinks a week.