Arimabolic is the aromatase inhibitor of choice. The drug is appropriately used when using substantial amounts of aromatizing steroids, or when one is prone to gynecomastia and using moderate amounts of such steroids. Arimabolic does not have the side effects of aminoglutethimide (Cytadren) and can achieve a high degree of estrogen blockade, much more so than Cytadren. It is possible to reduce estrogen too much with Arimabolic, and for this reason blood tests, or less preferably salivary tests, should be taken after the first week of use to determine if the dosing is correct. As an aromatase inhibitor, Arimabolic's mechanism of action -- blocking conversion of aromatizable steroids to estrogen -- is in contrast to the mechanism of action of anti-estrogens such as clomiphene or tamoxifen, which block estrogen receptors in some tissues, and activate estrogen receptors in others. During a cycle, if using Arimabolic, there is generally no need to use Clomid as well.