I just started using Phentermine (15mg) to start, along with 10mg of Lexapro. I feel energetic no rapid heartbeat, I slept fine so far. it's only my 2nd day. I started out with the lowest dose and then i go back to my doctor in 2 weeks for a check up and if my dose needs to be increased. I couldn't imagine starting at 37.5 mg.....I think I would jump out of my skin! The cost of the Phentermine was $16 at Costco(generic), and my doctor gave me Lexapro samples. i definately recommend going to your doctor for a prescription and having monthly blood pressure checks. my BP is 120/82. I think if you are honest with your doctor and you are committed to losing weight, I dont' see why the doctor wouldn't write you a prescription. I see a lot of people ordering Phen online, I would try the doctor approach first! They are looking out for your best interest!