I'm always very careful with my blood pressure... I actually bought one of the blood pressure monitors. But HBP runs in my family, so I need to be very careful of it. Fortunately, at least thus far, I have no problems with it.
As for the diet pills, they are often terrible for your blood pressure. They are packed with caffeine (which is bad news bears anyway), and many other energy supplements. I get the idea behind it, but I'm not a fan of artificial energy. I had to rely on caffeine for work (but that's because I was made to stay up for 2-3 days rather consistently, and a "good nights sleep" was more than 4 hours). I had an important job, but I was exhausted and sick all of the time from it. I actually passed out a few times, and ended up with a concussion once!
My conclusion.....fake energy makes me very nervous, and I avoid it like the plague now. The most caffeine I'll have is in some dark chocolate or some tea (on a rare occasion). My circumstances were extreme, though. I'm sure if properly applied they work wonders for some people!! I'm just petrified of artificial energy products because of my own experiences with them.