So I was looking at reasons I suddenly had high blood pressure the past few years! I looked at Dunkin’ Donuts online and found out my single medium iced coffee contains over 400mg of caffeine and sometimes I get two shots bringing it to 500 or more. When I started drinking coffee is when I believe I developed these issues. I am sensitive to caffeine as well. I also read 400 mg is normal? Can someone give me some insight on this ? My bp last few years is 145 to 155 over 85 to 89. I am going off cold turkey for a week. Should I instantly see improvement or wait it out to clear out of system?