Oestrogel Pump-Pack transdermal HRT gel on a menopausal womans bedside table

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. 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 marketed under a large number of brand names throughout the world. Examples of major brand names in which estradiol has been marketed in include Climara, Climen, Dermestril, Divigel, Estrace, Natifa, Estraderm, Estraderm TTS, Estradot, Estreva, Estrimax, Estring, Estrofem, EstroGel, Evorel, Fem7 (or FemSeven), Imvexxy, Menorest, Oesclim, OestroGel, Sandrena, Systen, and Vagifem