Tamoxifen Citrate is a Selective Estrogen Receptor Modulator (SERM) that was created in 1961 by ICI now known as AstraZenaca. Often referred to as an anti-estrogen, Tamoxifen Citrate is actually both an antagonist and agonist. This means it will act as an anti-estrogen in certain areas of the body while acting as an estrogen in other areas.

Tamoxifen Citrate has been used medically for decades and has been highly successful in breast cancer treatment, specifically hormone-responsive breast cancer. It is also a medication that is used by many anabolic steroid users, but it is not a steroid. This is a drug steroid users will sometimes use during steroid use to help with estrogenic related side effects brought on by specific steroids. However, it is most commonly used during Post Cycle Therapy (PCT).