What is the safest diet pill to take when you have high blood pressure?

i have tried everything imaginable short of not eating or surgery to lose these last 30-50 lbs, nothing is working. i take meds for high blood pressure but i also drink alot of caffeine a day. if i gave up the caffeine could i take a diet pill safely? somebody help me! i'm really self concious about my weight and summer is coming, i work in a warehouse loading trucks and would like to be able to wear a tank top and not look like a stick with a tire in the middle.................please!