sarah - i've not personally used them,but speaking as the wife of a truckie and daughter of a taxi driver that have both used them in the past (my dad long term). in all honesty, i wouldn't recommend them - DH has admitted that the basis of them is a type of legal speed - they're not really healthy, don't necessarily work the way they should, and can have some nasty side effects as kim outlined. i know it can be really frustrating when you just want the weight gone, but i know from hearing my dad whinge that there are very few doctors who will prescribe them because there are far too many side effects

my understanding is that they speed your heart rate so i don't think it would be recommended to do anything that messes with your heart if you already have bp issues..