An<unk> (E) is a type of medication which is used most commonly in hormonal birth control and menopausal hormone therapy, and as part of feminizing hormone therapy for transgender women. They can also be used in the treatment of hormone-sensitive cancers like breast cancer and prostate cancer and for various other indications.<unk>  are used alone or in combination with progestogens. They are available in a wide variety of formulations and for use by many different routes of administration. Examples of<unk>  include bioidentical estradiol, natural conjugated<unk> , synthetic steroidal<unk>  like ethinylestradiol, and synthetic nonsteroidal<unk>  like diethylstilbestrol.<unk>  are one of three types of sex hormone agonists, the others being androgens/anabolic steroids like testosterone and progestogens like progesterone. Side effects of<unk>  include breast tenderness, breast enlargement, headache, nausea, fluid retention, and edema among others. Other side effects of<unk>  include an increased risk of blood clots, cardiovascular disease, and, when combined with most progestogens, breast cancer. In men,<unk>  can cause breast development, feminization, infertility, low testosterone levels, and sexual dysfunction among others.<unk>  are agonists of the<unk> receptors, the biological targets of endogenous<unk>  like estradiol. They have important effects in many tissues in the body, including in the female reproductive system (uterus, vagina, and ovaries), the breasts, bone, fat, the liver, and the brain among others. Unlike other medications like progestins and anabolic steroids,<unk>  do not have other hormonal activities.<unk>  also have antigonadotropic effects and at sufficiently high dosages can strongly suppress sex hormone production.<unk>  mediate their contraceptive effects in combination with progestins by inhibiting ovulation.<unk>  were first introduced for medical use in the early 1930s. They started to be used in birth control in combination with progestins in the 1950s. A variety of different<unk>  have been marketed for clinical use in humans or use in veterinary medicine, although only a handful of these are widely used. These medications can be grouped into different types based on origin and chemical structure.<unk>  are available widely throughout the world and are used in most forms of hormonal birth control and in all menopausal hormone therapy regimens.
Estrogen 
Estradiol 
Estradiol
Androgen
Sex hormone
Progesterone
Progesterone 
Estriol