Hello. I was on carbimazole to treat my overactive thyroid. I read that I was meant to be on it for 18 months. However, I was taking it for 18 years. I am wondering what this has done to me as my health is quite poor. (The thyroid was eventually dosed with radioactivity and I'm now on levothyroxin.) Has anyone any information about carbimazole when taken for much longer than usual? Thank you. Timon.