Does tylenol and nyquil combination kill fast or slow?

I'm writing a short story for my english class, and I chose to write a fictional zombie apocalypse story since we chose our own subjects, and I wanted to kill one character off by having her commit suicide when her barricade fails and she's locked in a room with no escape, and all she has in the room with her are some household pills and such, and I heard that the combination of nyquil and tylenol pm can kill you, and I was wondering if that combination would make you pass out and then kill you or if it would take time, because I know it kills your liver, but how long would it take you to actually die from it? I just don't want to make it unrealistic and have her die right away if she does that combination