I personally wouldn't take Dexatrim, or any other popular diet pill, such as NV, Trimspa, etc.
These pills don't really do anything except give you a "lift" (think caffeine, speed, etc.) They don't burn fat, or do anything to make you lose weight. The problem with these things, is that they are on the market for a while, and then there are illnesses and deaths at times with the "active ingredient", and then they all get taken off the market. Then, the companies find or make a new active ingredient, put it back out there, and a few years later the same thing happens...
They took the original Dexatrim and its store brand forms off the market in the 90's (the one that sold through the 70's and 80's) due to some deaths, etc. Then they put all the pills out there that had ephedra in them. A few years ago that was taken off the market (and the cold medicines, etc. with it started being held behind the counter at the pharmacy) and now there are other ingredients in them instead.
Why take the risk?
A reduced calorie diet, and moderate exercise are the key.