Transgender hormone therapy in the context of "Feminizing hormone therapy"

A transsexual person is someone who experiences a gender identity that is inconsistent with their assigned sex or gender, and desires to permanently transition to the sex or gender with which they identify, usually seeking medical assistance (including gender affirming therapies, such as hormone replacement therapy and gender affirming surgery) to help them align their body with their identified sex or gender.

The term transsexual is a subset of transgender, but some transsexual people reject the label of transgender. A medical diagnosis of gender dysphoria can be made if a person experiences marked and persistent incongruence between their gender identity and their assigned sex.

A sex-hormonal agent, also known as a sex-hormone receptor modulator, is a type of hormonal agent which specifically modulates the effects of sex hormones and of their biological targets, the sex hormone receptors. The sex hormones include androgens such as testosterone, estrogens such as estradiol, and progestogens such as progesterone. Sex-hormonal agents may be either steroidal or nonsteroidal in chemical structure and may serve to either enhance, inhibit, or have mixed effects on the function of the sex hormone systems.

Sex-hormonal agents are used in medicine for a variety of purposes including hormone therapy (e.g., menopausal hormone therapy, androgen replacement therapy, transgender hormone therapy), antihormone therapy (e.g., androgen deprivation therapy, estrogen deprivation therapy), and hormonal contraception, among others.

Estradiol undecylate (EU, EUn, E2U), also known as estradiol undecanoate and formerly sold under the brand names Delestrec and Progynon Depot 100 among others, is an estrogen medication which has been used in the treatment of prostate cancer in men. It has also been used as a part of hormone therapy for transgender women. Although estradiol undecylate has been used in the past, it was discontinued. The medication has been given by injection into muscle usually once a month.

Side effects of estradiol undecylate in men may include breast tenderness, breast development, feminization, sexual dysfunction, infertility, fluid retention, and cardiovascular issues. Estradiol undecylate is an estrogen and hence is an agonist of the estrogen receptor, the biological target of estrogens like estradiol. It is an estrogen ester and a very long-lasting prodrug of estradiol in the body. Because of this, it is considered to be a natural and bioidentical form of estrogen. An injection of estradiol undecylate has a duration of about 1 to 4 months.