Late Dec, 2012 I was diagnosed with over active thyroid, I was feeling unwell ,racing heart,sweat..etc.Life was miserable. I started Carbimazol 20mg/daily. I did not notice any difference until towards the end of the third week . My blood test came yesterday all fine with conservable drop in T4 . My Gp decided to reduce my dose to 15mg/day. But TSH is still way low, any idea who long it takes before I start to see it up again.