Do not take Fosamax more than 2 years without taking a break. Because now they are finding out that long term Fosamax use causes very brittle bones. Even if your bone density is normal. I took Fosamax X 6 yrs at age 35, my bones were severe osteoporosis (my bones were the age of a 76-yr old). Now my bones r very brittle. I have had 4 fractures in 3 yrs. This info is from my bone Dr.