I started having bad leg and foot cramps when I began taking tamoxifen after BC surgery last year. I continue to have them, but less so, with anastrozole. I get some relief from Magnesium Glycinate, which I take at night for both sleep and cramps. I have noticed that cramps and dehydration are related, so I drink lots of fluids when working outside, and a gatorade drink if it is really hot and/or I am doing something strenuous. Still, the cramps (and sleeping) got worse with an estrogen blocker.