I think it's not too far off the mark to say we poison ourselves by drinking the way we do - thats what the word intoxicate originally meant :
Late Middle English (in the sense ‘poison’): from medieval Latin intoxicare, from in- ‘into’ + toxicare ‘to poison’, from Latin toxicum (see toxic).
It takes a while for our mind and body to get back to normal, and the more years we drink, generally the longer and more vicious withdrawal can be.
Look up 'alcoholic kindling'.
D