I’m not a doctor, but since caffeine constricts blood vessels it seems like it could raise blood pressure. My guess is people who consume caffeine regularly (daily and consistently not going into complete withdrawal) the caffeine probably has little effect.
The thing is, knowing what is usually the case for most people doesn’t matter at all, what matters is does it affect your body.
If you have high blood pressure and want to experiment I say do it. You can take your blood pressure before and an hour after caffeine. Even better you can take your blood pressure two or three times a day for a couple of weeks, get a baseline, and then quit caffeine (wean down over 4 or 5 days, plan on feeling crappy) and then take your blood pressure twice a day for a few weeks once you are completely off the stuff.
If you don’t have high BP I wouldn’t worry about it at all, but that’s me.
A side note: if you have high BP my dad recently was able to completely stop BP medicine after 20 years of taking the drugs by eating a low glycemic diet. He also quit drinking alcohol; he used to drink on or two glasses of wine at night. He lost 20 pounds from the changes in diet also.
I’ve seen alcohol have dramatic affect on some people’s blood pressure. My dad credits the low glycemic diet, but no way to know exactly was the cure of his high BP.