Ethinyl estradiol in combination with cyproterone acetate, a progestational antiandrogen, was given to 20 male-to-female (M-F) transsexuals, and parenteral testosterone esters were given to 17 female-to-male (F-M) transsexuals. estradiol (patch = Estradot ®, Estraderm®, or Oesclim ; pill form = Estrace®) is used because it has the least health risks. Conjugated estrogens (., Premarin®) and ethinyl estradiol are not recommended because studies of non-trans women have shown them to increase the risk of some types of health problems. 3