What's the process of dying after taking pills?

I can't see it just being 'poof-your dead'. I can't see it being easy, i mean you'd have to take a lot, too, right? So would would happen if you took about 30 advil/tylenols. IM NOT ASKING BECAUSE IM PLANNING TOO. My mother did this to herself when i was very little... So i mean out of curiousity, what happens first? do you just p out and then organs start to fail? or are you concious of whatever pain might be caused. is there any pain caused? sorry if im wording this weird.