Respuesta :

Coffee is a stimulant while alcohol is a depressant, both target different functions of the brain and while mixed together can have serious effects. 
Not only do they dehydrate you but caffeine and alcohol together can be toxic to the body, though it isn't fully able to understand on why but scientists have discovered it has the ability to impair one's judgement even more than alcohol alone. Mixed together both substances do not cancel each other out.

read more here: https://medicalxpress.com/news/2010-11-alcohol-caffeine-deadly.html