Anastrozole (Arimidex)

Anastrozole is in a class of medications called nonsteroidal aromatase inhibitors. In clinical use, it´s used to halt the progression of breast cancer in women. It works by blocking the aromatase enzyme, which is responsible for the production of estrogen.

Anastrozole has proven effective in the off-label use of reducing estrogens (in particular and more importantly, estradiol) in men. Excess estradiol in men can cause benign prostatic hyperplasia, gynecomastia, and symptoms of hypogonadism. Some athletes and body builders will also use anastrozole as a part of their steroid cycle to reduce and prevent symptoms of excess estrogens; in particular, gynecomastia and water retention. Study data currently suggest that dosages of 0.5 mg to 1 mg a day reduce serum estradiol by about 50% in men, which differs from the typical reduction in postmenopausal women. However, the reduction may be different for men with grossly elevated estradiol.