Tamoxifen citrateis a non-steroidal anti-estrogenic drug, used widely in clinical medicine. It is specifically a Selective Estrogen-Receptor Modulator (SERM) of the triphenylethylene family and possesses both estrogen agonist and antagonist properties. As such, it may act as an estrogen in some tissues while blocking the action of estrogen in others. The primary worry among the athletic/bodybuilding population is gynecomastia or the very unsightly development of female breast tissue in men. This can be first noticed by the appearance of swelling or a small lump under the nipple. If left to progress, this can develop into large hard-tissue gynecomastia that may be an irreversible occurrence without surgery. The estrogen can also lead to an increase in the level of water retained in the body, resulting in a notable loss of definition as the muscles begin to look smooth (even bloated) due to the retention of subcutaneous fluid. Tamoxifen prevents that.
The typical recommended dosage is 20–40 mg per day taken in one or divided doses.