I've been on Phentermine 37.5 since last Friday. On Fri-Mon I felt great. I had a ton of energy, didn't sleep much but seemed well rested when I woke, I had to force myself to eat and drink, and I did have dry mouth. On Tuesday I weighed and had lost 5 pounds in 5 days which I was so proud of. Starting Tuesday night I started having horrible hot flashes but my hands were like icicles, dizziness, heart racing, not near as energetic, very sleepy, very irritated, feel like I could pass out, etc. I know I have not been eating or drinking near as much as I should so today I've made myself eat and drink even more but still kind of feel this way. I just don't know what to do. I have a call into my doctor so we will see what he says but I wondered if anyone else had any of these side effects and what you ended up doing to make it better?