My dr prescribed me phentermine to help me lose the 20 lbs I have gained back. I took my first dose this morning at 7am and started vomiting at 10. I have been in bed/on sofa since and every time I get up I feel sick. Has anyone had this happen? Would love to know how long this lasts because I have a huge day tomorrow ugh!

Well hopefully you are feeling better now. It may be that the vomiting wasn't related to the phentermine.

According to the Internet:

Side effects of using phentermine are dizziness, dry mouth, difficulty sleeping, irritability, nausea, vomiting, diarrhea, or constipation may occur. If these effects persist or worsen, notify your doctor or pharmacist promptly. This medication may raise your blood pressure.

Hope you're feeling better. I didn't vomit on Phentermine, but my RESTING heart rate was 163, so I was pulled off of it real quick.

WOW this is very surprising to me. It is no longer recommended due to the side effects.