From my experience - clomid is EVIL! I took clomid once - 50mg. It didn't make me ovulate, but sent me into such a bad headspace with anxiety that I had to take about two weeks off work. Evil, horrible, nasty drug!

Letrozole - the side effects only lasted while I took the tablets. I still had a rise in anxiety levels, but it was tolerable. It's something that happens to me any time my estrogen levels get elevated, so it will happen every time before I ovulate no matter what the method is used to make me ovulate.

I know most people don't have the reaction to clomid that I did, but it seems from my reading that letrozole works at lower doses with less side effects and while I've heard of a lot of women failing to ovulate with clomid, I've never heard of someone failing to ovulate with letrozole. Could be because of the much lower women who have tried it though.

The other difference is that whichever hormone needs to be turned off to cause the ovulation to happen - the clomid stops the body from seeing it, while the letrozole stops the body from making it. That's why it works better. Damn shame I can't remember any more of the technical stuff from that and I have no idea where the papers my FS gave me are.

BW