Anastrozole is an anti-estrogenic drug developed to block the production of estrogen in the body. The effects of anastrozole can be very substantial, with a daily dose of 1 mg (commonly 1 tablet) capable of producing estrogen suppression greater than 80% in treated patients. The popularity of Anastrozole is due to its affordability and ease of use. For the anabolic steroid user, Anastrozole is highly efficient and should be the only Aromatase Inhibitor (AI) and a preventative measure you need. However, in cases where gynecomastia symptoms are already beginning to show.