Interesting topic and very helpful. I started Letrozole by Femara beginning of May last year. Saw my oncologist in Nov The differences I noticed was stiff hands first thing in the morning. Several months of lower back pain. My husband would have to massage and pummel the lower back area for about 5 mins and then I'd be heaps better.. I could barely get dressed. I have a bit of arthritis and tendonitis there also. The onc thought Letrozole was aggravating it. The worst was having very sudden onset migraines, very painful lasting up to 10 hours and vomiting. They came on like a light switch. Missed some very important events laid up with that.. Because of that she changed me over to Anastrozle Sandoz, which is a sister to Letrozole. She thought that the Letrozole could be causing the symptoms. Going back in the morning to see oncologist after 6 weeks on new meds. Have to say my hands are not sore anymore. I did have a whopper migraine 3 days after starting new meds but I wouldn't say they were to blame Also had a 4 hour headache which was an ache and not the pain of a migraine. The annoying part is that painkillers do absolutely nothing for it. I went to my GP who had prescribed me Panadeine Forte luckily not needed so far. I did have another episode for a couple of weeks with my back but at the moment it's settled down. So all in all, I think the Anastrozle is suiting me better.. I often wondered how others went on Letrozole. We are all individuals and will react differently to medications but interesting to see that there are common symptoms.. I look at it as the price we have to pay for this extra insurance. After my 2 hour trip to work on the train I have to tell myself as I get out of my seat that I'm 16, not 68 and to not walk like I'm 94 because that's how I feel sometimes lol.