Arimidex is the brand name of the generic drug Anastrazole, used to treat breast cancer in postmenopausal women. Arimidex belongs to class of drugs known as nonsteroidal aromatase inhibitors, which slow or stop the growth of breast cancers that are stimulated by estrogen by decreasing the amount of estrogen the body makes after menopause. Arimidex may also be used for purposes not listed in this medication guide.

Pregnancy and Arimidex. Arimidex is an FDA Pregnancy Category X drug, meaning it causes birth defects. You should tell your doctor if you are pregnant or plan to become pregnant before taking this medication. The drug is not recommended for breastfeeding mothers, though whether or not it is safe remains unclear. You should tell your doctor if you are breastfeeding or plan to breastfeed before taking Arimidex.