Try to not worry too much about side effects--they are just possibilities. I've tolerated letrozole without any side effects for a year, but I simply told myself that if I couldn't handle it I'd look for other options. I haven't experienced Fosomax, but if you are on letrozole or even of a certain age you should be monitored for osteopenia and osteoporosis. There should hopefully be warning time with this, and different ways to treat. And there is plenty of osteoporosis without AI. Basically taking any drug does not doom you to nasty side effects--just allow yourself to re-evaluate as you go and not be pressured. Pharmacology, medical science, and all of us as people are in constant flow of change. Try making the best (not perfect) decision for the time, and take good care of yourself!