I have been diagnosed with pcos but I have normal periods and TSH. The only problem is that I have acne on my jaw line and neck and not in other parts of face. My blood sugar is also normal. My weight is 80kg now. Five years back my weight was 67 and the skin acne started and I went to skin specialist and was cream and other medications. But the acne kept coming back inspite of proper diet. My weight also increased from 67 kg. Now, I was diagnosed with pcos from the scan done and was advised metformin 500 mg twice daily. This has reduced my acne and a good skin My weight is hovering around 80 kg. How long should I be taking this medicine?