estradiol (medication) estradiol (medication) estradiol (e2) is a medication and naturally occurring steroid hormone. it is an estrogen and is used mainly in menopausal hormone therapy and to treat low sex hormone levels in women. it is also used in hormonal birth control for women, in hormone therapy for transgender women, and in the treatment of hormone-sensitive cancers like prostate cancer in men and breast cancer in women, among other uses. estradiol can be taken by mouth, held and dissolved under the tongue, as a gel or patch that is applied to the skin, in through the vagina, by injection into muscle or fat, or through the use of an implant that is placed into fat, among other routes. this article is about estradiol as a medication. for its role as a hormone, see estradiol. estradiolclinical datapronunciation/ˌɛstrəˈdaɪoʊl/ es-trə-dy-ohl trade namesnumerousother namesoestradiol; e2; 17β-estradiol; estra-1,3,5(10)-triene-3,17β-diolahfs/drugs.commonographpregnancycategory au: b1 routes ofadministration• by mouth (tablet)• sublingual (tablet)• intranasal (nasal spray)• transdermal (patch, gel, cream, emulsion, spray)• vaginal (tablet, cream, suppository, insert, ring)• im injection (oil solution)• sc injection (aq. soln.)• subcutaneous implantdrug classestrogenatc codeg03ca03 (who) legal statuslegal status au: s4 (prescription only) ca: ℞-only uk: pom (prescription only) us: ℞-only eu: rx-only in general: ℞ (prescription only) pharmacokinetic databioavailabilityoral: <5%im: 100%protein binding~98%:• albumin: 60%• shbg: 38%• free: 2%metabolismliver (via hydroxylation, sulfation, glucuronidation)metabolitesmajor (90%):• estrone• estrone sulfate• estrone glucuronide• estradiol glucuronideelimination half-lifeoral: 13–20 hourssublingual: 8–18 hourstransdermal (gel): 37 hoursim (as ev): 4–5 daysim (as ec): 8–10 daysiv (as e2): 1–2 hoursexcretionurine: 54%feces: 6%identifiers iupac name (8r,9s,13s,14s,17s)-13-methyl-6,7,8,9,11,12,14,15,16,17-decahydrocyclopentaphenanthrene-3,17-diol cas number50-28-2 ypubchem cid5757iuphar/bps1013drugbankdb00783 ychemspider5554 yunii4ti98z838ekeggd00105 ychebichebi:16469 ychemblchembl135 ychemical and physical dataformulac18h24o2molar mass272.388 g·mol−13d model (jsmol)interactive image smiles c12cc3(1cc2o)ccc4=c3c=cc(=c4)o inchi inchi=1s/c18h24o2/c1-18-9-8-14-13-5-3-12(19)10-11(13)2-4-15(14)16(18)6-7-17(18)20/h3,5,10,14-17,19-20h,2,4,6-9h2,1h3/t14-,15-,16+,17+,18+/m1/s1 ykey:voxzdwnpvjitmn-zbrfxrbcsa-n y (verify) side effects of estradiol in women include breast tenderness, breast enlargement, headache, fluid retention, and nausea among others. men and children who are exposed to estradiol may develop symptoms of feminization, such as breast development and a feminine pattern of fat distribution, and men may also experience low testosterone levels and infertility. estradiol may increase the risk of endometrial hyperplasia and endometrial cancer in women with intact uteruses if it is not taken together with a progestogen such as progesterone. the combination of estradiol with a progestin, though not with oral progesterone, may increase the risk of breast cancer. estradiol should not be used in women who are pregnant or breastfeeding or who have breast cancer, among other contraindications. estradiol is a naturally occurring and bioidentical estrogen, or an agonist of the estrogen receptor, the biological target of estrogens like endogenous estradiol. due to its estrogenic activity, estradiol has antigonadotropic effects and can inhibit fertility and suppress sex hormone production in both women and men. estradiol differs from non-bioidentical estrogens like conjugated estrogens and ethinylestradiol in various ways, with implications for tolerability and safety. estradiol was discovered in 1933. it became available as a medication that same year, in an injectable form known as estradiol benzoate. forms that were more useful by mouth, estradiol valerate and micronized estradiol, were introduced in the 1960s and 1970s and increased its popularity by this route. estradiol is also used as other prodrugs, like estradiol cypionate. related estrogens such as ethinylestradiol, which is the most common estrogen in birth control pills, and conjugated estrogens (brand name premarin), which is used in menopausal hormone therapy, are used as medications as well. in 2020, it was the 59th most commonly prescribed medication in the united states, with more than 11 million prescriptions. it is available as a generic medication. medical uses menopause