Bless you... or... not?

I was put in a situation the other day which although I have experienced a number of times, still found myself wondering how to react. It's such a simple, everyday habit: Sneezing. Im sure you've probably been in the same boat a time or two. Someone near you sneezes. Naturally, you offer up some sort of response (hopefully not "Gazoontite" because that word is teetering on making my loathe list.) Now in some cases, if your lucky, thats the end of the story. My question is this: What are you supposed to do if that person continues to sneeze? It's only minimally awkward if you have to repeat yourself once, but you know there's been instances where the frenzy continues on for several more. Not only do you feel uncomfortable for making the decision to continue on for four "bless you's," but the other person is also frantically trying to stop in embarrassment for forcing you to do so. Surely mankind has experienced this enough to have come up with some relatively uncomplicated answer. Do you respond once? Do you stop after 3? Do you nervously laugh after realizing you have indeed gone too far? Or do you just ignore the germ-spreading convulsive expulsion altogether? Life sure is complicated...