"this is a very effective drug, but as with any drug, there are side effects.  i found the stimulant effect to be a bit overwhelming at first (37.5mg every morning) but your body will adjust.  over a period of weeks you will notice a tolerance as your body gets used to the drug and, in my case, the dosage will need to be adjusted.  along with phentermine, my doctor prescribed a low-dose diuretic (lasix 10mg), low-dose potassium supplement, and a regular vitamin b12 injection.  i was extremely impressed with the overall results, however, one needs to keep in mind that the results will only be temporary without a change in lifestyle (i.e., caloric diet restriction and regular exercise)."