Driada Medical "Nolvados" (Tamoxifen Citrate) citrate is called an anti-estrogen, but in fact it is an antagonist. This means that it acts as an anti-estrogen in certain parts of the body and as estrogen in certain areas of the body. Tamoxifen is most commonly used to treat breast cancer because some cancers require high levels of the hormone estrogen. Tamoxifen is a medication used by anabolic steroid users, but tamoxifen is not a pure steroid. Since this is a medication that athletes who use steroids are sometimes used during cycles to help themselves during the estrogen side effects caused by certain steroids.