What can xanax, (alprazolam) klonopin and vistaril do to a person?

Together? All 3 are used as sedatives or tranquilizers. Xanax (alprazolam) & Klonopin (clonazepam) are benzodiazepines, vistiril (hydroxyzine) is a sedating antihistamine. "benzos" can be addictive, especially short-acting ones like xanax. Vistiril isn't. It's usually not good to take all 3 of these together: the 2 benzos can "add together" & increase side-effects, & all 3 can impair driving & alertness.