estrogen. However, while being an antagonist it is also an agonist as it will actually act as estrogen in certain parts of the body while acting as an anti-estrogen in other areas. As one of the oldest SERM’s on the market that is still regularly used medicinally, while Nolvadex is also used by anabolic steroid users it is not an anabolic steroid. This is an important note as some are often confused by its use in steroid cycles. Nolvadex is simply a SERM.