What would Drano do if injected?

I remember watching a movie where someone took someone hostage with a needle full of Drano. She's doesn't inject him though. What would something like that do? Looking for a realistic answer, not "The actor would pretend to die..." xD. Thanks! And as for diluted chemicals, would things like raid do the same? And how long would it take for a corrosive like diluted lye to affect the body internally? Thanks again to all serious answers.