I was on Anastrozole for 2 months and asked to be switched due to extreme stiffness. My oncologist took me off all meds for two weeks (a welcome, symptom-free vacation!) then I started Letrozole. I'm experiencing a bit less stiffness, and definitely nighttime leg cramps. I started taking a magnesium supplement at bedtime and that has helped significantly with the leg cramping. Walking and hydrating are important too. Not a fun process......but the outcome is important.