Nolvadex D 20mg (30 tablets) contains tamoxifen, a medication used primarily to treat hormone receptor-positive breast cancer. It works by blocking estrogen's effects on cancer cells, which can help slow or stop the growth of certain types of breast cancer that rely on estrogen to grow. Tamoxifen is often used in both early and advanced stages of breast cancer, and can also be used as a preventive treatment for women at high risk of breast cancer.