It is no surprise that mixing cleaning chemicals can be a deadly business. But why exactly is it so dangerous, and what specifically should not be mixed? The main cleaner that can NOT be mixed with other cleaning agents is chlorine bleach. The active ingredient in bleach is sodium hypochlorite, which can be corrosive to the skin and mucous membranes and can even cause severe injury to the eyes. Chlorine bleach is basically chlorine gas in water. When it is mixed with other chemicals, deadly gases can be produced.