I did when I was 16. I was dx with PCOS at age 16, started taking it right away. I an't even begin to tell you how Metformin made me feel. I was bloated, vomitting, I think that is why I lost so much weight on it. So I went to the docs, and I told them that I wasn't able to handle the side effects of the medication. I am now 24, and I am Metformin again..I am on 500 mg BID (twice a day), and I have been on it for 3 months now. I am moving up to 750mg BID in two weeks.