Anastrozole (Arimidex) is a drug indicated in the treatment of breast cancer in post-menopausal women. It is used both in adjuvant therapy (i.e. following surgery) and in metastatic breast cancer. It has the effect of decreasing the amount of estrogens that the body makes.

Anastrozole belongs in the class of drugs known as aromatase inhibitors. It inhibits the enzyme aromatase, which is responsible for converting androgens (produced by women in the adrenal glands) to estrogens.

While officially indicated for women, this drug 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 suggests that dosages of 0.5mg to 1mg 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 (clinical data is currently lacking).

Before taking any prescription medicine, it is important that you consult your doctor!