The only side effect of Arimidex is low estrogen. It has no other effects.
I know why you say this. When you browse through the steroid forums, all of the sides can be explained by this. However, I think it's naive - and I'm not trying to be insulting here - to think that any pharmaceutical is without side effects long term. I cannot think of one pharmaceutical that does not affect some other outside, unexpected system. It also seems gentle on the liver.
Again, I remember when they told me that the old line antihistamines were fine and they turned out to affect memory.
Let me ask this question: if Arimidex binds to AI, can we say for sure it does not affect any other enzyme system?
In addition, Arimidex does seem imo to produce sides in the brain. Guys get weird mood and other changes. Yes, this could be estrogen, but to me it seems a bit more than that.
That's just my two cents...