How does a human react when you mix heroin with vodka?

Bad Mix, Both Heroin and Vodka are Central Nervous System Depressants.

Heroin depresses the nervous system in the brain and too much may slow breathing.

Alcohol also depresses the nervous system.

By combing heroin and alcohol; the effects of both drugs combine and double in nervous system depressing effects; therefore there is a high chance you could die.

Again Don't even try to mix the two, very deadly combination.