HI, I have been taking Arimidex for about 5 months. I am also very sensitive to drugs. It's a curse, really. I had a difficult time in the beginning. I didn't feel well, I was very tired, I wasn't sleeping well and I had didn't have a good attitude about taking it. I went to see my doctor and told him I just couldn't hack it. He told me to give it awhile longer and then go off if I needed to. Low and behold during the 3rd month I started to feel much better. I was also very resistant to taking the drug. I really didn't commit to it in my mind and kept thinking I was going off. I didn't like the idea of every bit of estorgen in my body being supressed. I think it was really difficult for me to adjust physically and mentally to Arimidex but I have adjusted and feel fine. Give it a go...and think of me if you have trouble and how I told myself everyday I was going to go off.