Arimidex may possibly help prevent side effects such as gynecomastia (male breast enlargement) from building because of the aromatization of anabolic steroids.tamoxifen. You shouldn't take ARIMIDEX if you take tamoxifen. Taking ARIMIDEX with tamoxifen might reduce the amount of ARIMIDEX with your blood and should result in ARIMIDEX not to work too.