I've been on Letrozole since the beginning of May and can't say I've noticed anything too bad. I have been a migraine sufferer on and off for nearly 50 years but I do now get very quick onset headaches which ordinary painkillers won't touch. The only way at present is to take another dose after an hour instead of waiting 4 hours. Our band had a gig when I got a headache before I left home, took 2 painkillers an hour later at the venue I went to a nearby chemist who couldn't suggest anything stronger as 6 months ago laws were changed which meant nothing stronger available without a script so he said it would be ok to take another dose Miraculously the headache went I suppose all of us react in different ways with certain similarities to these ongoing hormone treatments. I'm just grateful that we at least have them. It's all a bugger isn't it.