Tamoxifen Citrate is a nonsteroidal antiestrogenic drug that is widely used in clinical medicine. It is specifically a selective estrogen receptor modulator of the triphenylethylene family and has both estrogen agonist and antagonist properties. As such, it can act as an estrogen in some tissues while acting as an anti-estrogen in others. In breast tissue, the drug is a powerful anti-estrogen and is therefore widely used in the treatment of estrogen-associated breast cancer in women. Tamoxifen Citrate was first developed by the pharmaceutical company ICI in 1962. It was commercially available in the United States not long afterwards, but its original use was for the treatment of female infertility, a goal for which the drug does not seem ideally suited for. It wasn't until 1977 that the FDA approved the drug for use in the United States for the treatment of breast cancer. The drug was sold by ICI under the brand name Nolvadex in a number of markets around the world.

In terms of its use in steroid users, Tamoxifen Citrate can help in two ways. First, because of the compound's binding affinity, it is able to aid in gynocomastia prevention. Tamoxifen will compete with estrogen for the estrogen receptors in certain tissues, including the breast, and when it binds to the receptor estrogen cannot have the ability to interact with the receptor and therefore gynocomastia should not be able to develop. When using anabolic steroid that can convert to estradiol (estrogen), this protection against gynocomastia can be invaluable. It should be noted, however, that tamoxifen citrate will not eliminate or allow the estrogen to be converted. Instead, it tries to counteract the effects of circulating estrogen in the body in the tissues that produce the drug effects. Hence, there is no evidence that tamoxifen citrate has any effects that counteract any etrogenic side effects that are not related to the tissues that are not in the breast, liver, or bones. In fact, there is no real causal relationship with a decrease in water retention and acne in users starting tamoxifen citrate, as it affects estrogen. The second and possibly more beneficial aspect of tamoxifen citrate for steroid users is its ability to increase the production of luteinizing hormone and follicle stimulating hormone, thus increasing testosterone. This ability is why it is often used by steroid users during their post cycle therapy. There are numerous studies that suggest that Tamoxifen Citrate can increase the amounts of these hormones quite dramatically. Tamoxifen Citrate does this by blocking the negative feedback inhibition caused by estrogen in the hypothalamus and pituitary, and this in turn will help to increase the production of these hormones. Unlike clomiphine citrate, tamoxifen citrate has also been shown to increase the response of luteinizing hormone to gonadotropin-releasing hormone. Clomiphin Citrate can decrease this responsiveness over time. A possible side effect of using tamoxifen citrate is the possible reduction in insulin-like growth factors. If these levels are reduced, this could suppress the gains an individual can easily make. However, this reduction, if actually present, would not be overly significant if the gains in muscle mass were only marginally reduced.