I had an M.D. prof swear up and down once that caffeine doesn't cause an increase in blood pressure, only heart rate. I disagreed with him on that and got several points off for incorrect answers relating to it on his exams. I don't know why he thought it did not happen at all...

Anyway, I think it can cause a slight increase in some people, but it is definitely NOT by any dangerous amount. You have to worry more about arrhythmias and tachycardia.

As for the boner... well, enjoy it.