One study shows a week of regular caffeine consumption by non-coffee drinkers had no effect on their blood pressure, heart rate, plasma renin activity, or urinary catecholamines
This afternoon I started to think about the effects of caffeine on blood pressure. A quick search online brought up much information and many studies, but this one from The National Center for Biotechnology (a .gov link) found this small section test on 18 average persons between the ages of 21 and 52 had no effects on the above aforementioned health tests.
Tolerance to the humoral and hemodynamic effects of caffeine in man.
D Robertson, D Wade, R Workman, R L Woosley, and J A Oates
Acute caffeine in subjects who do not normally ingest methylxanthines leads to increases in blood pressure, heart rate, plasma epinephrine, plasma norepinephrine, plasma renin activity, and urinary catecholamines. Using a double-blind design, the effects of chronic caffeine administration on these same variables were assessed. Near complete tolerance, in terms of both humoral and hemodynamic variables, developed over the first 1-4 d of caffeine. No long-term effects of caffeine on blood pressure, heart rate, plasma renin activity, plasma catecholamines, or urinary catecholamines could be demonstrated. Discontinuation of caffeine ingestion after 7 d of administration did not result in a detectable withdrawal phenomenon relating to any of the variables assessed.
You can read the full text here; Tolerance to the humoral and hemodynamic effects of caffeine in man.