I was drinking 8-10 cups of coffee a day for a couple years, but on the weekends I wouldn't have any and I would be fine. I thankfully did not have averse health problems, but I ended up being put on adderall as my doc thought I might have ADD. I immediately cut my intake to 1, maybe 2 cups a day as anymore would make me sick.

I went off adderall as it was not a great solution, turned out I was mostly miserable and bored at that company. I was trying to keep myself engaged by getting high on caffeine. After quitting, I drink 3-4 cups a day and some days none.