Anastrozole lowers estrogen levels in postmenopausal women, which may slow the growth of certain types of breast tumors that need estrogen to grow in the body.
Anastrozole is used to treat breast cancer in postmenopausal women. It is often given to women whose cancer has progressed even after taking tamoxifen (Nolvadex, Soltamox).
Anastrozole may also be used for purposes not listed in this medication guide.
 
What is the most important information I should know about Arimidex (Anastrozole)?
You should not use anastrozole if you are allergic to it, or if you have not yet completed menopause.
Anastrozole is not approved for use in men or children.
You should not take anastrozole if you also take tamoxifen.
Tell your doctor if you have ever had:
heart problems;
coronary artery disease (clogged artery disease);
high cholesterol; or
osteoporosis or low bone mineral density.
Hormonal cancer treatment can weaken your bones. You may be more likely to have a broken bone while using anastrozole. Talk with your doctor about ways to keep your bones healthy.
Although it is not likely that a postmenopausal woman would be pregnant, anastrozole may harm an unborn baby. You may need to have a negative pregnancy test before starting this treatment. Use effective birth control if you are not past menopause. Keep using birth control for at least 3 weeks after your last dose of anastrozole. Tell your doctor if you become pregnant.
Do not breastfeed while using this medicine, and for at least 2 weeks after your last dose.