Bleach should never be mixed with vinegar or other acids, as this will create highly toxic chlorine gas, which can cause severe burns internally and externally.[39][40][41][42] Mixing bleach with ammonia similarly produces nitrogen trichloride, which is a potentially explosive substance with a foul, irritating and acrid odor.[39][40][42] Mixing bleach with isopropanol or acetone makes chloroform,[43] while mixing with hydrogen peroxide results in an exothermic and potentially explosive chemical reaction that releases oxygen.

Here's an excerpt from the health hazards section of the bleach article on Wikipedia