Estrogens

Female sex hormones used for menopausal symptoms, to prevent bone loss and to replace missing ovarian hormones, at the lowest dose for the shortest time.

Updated Nov 1, 2026

What they are

Estradiol, conjugated estrogens and related compounds that act on estrogen receptors. They relieve hot flushes and vaginal atrophy after menopause, prevent postmenopausal osteoporosis when other drugs are unsuitable, and replace hormones in hypogonadism or premature ovarian insufficiency. Ethinylestradiol in contraceptives belongs to the same family. A woman with a uterus also takes a progestogen.

Mechanism of action

Estrogens cross the cell membrane and bind estrogen receptors α and β, nuclear receptors that switch genes on or off. They maintain the vaginal and urinary epithelium, stabilise temperature control, slow bone resorption, change liver protein synthesis (more clotting factors, SHBG and thyroid-binding globulin) and, through negative feedback, lower LH and FSH. Unopposed, they stimulate endometrial and breast tissue.

Target: Estrogen receptors α and β (ESR1, ESR2), nuclear receptors

Drugs in this class

Others in the class

Ethinylestradiol
Estriol
Estetrol
Esterified estrogens

Test yourself

Think of the answer, then tap the question to see it.

Which cancer does unopposed estrogen cause, and how is it prevented?

Endometrial cancer (after hyperplasia); adding a progestogen in women with a uterus prevents it.

Why might a woman on levothyroxine need a higher dose after starting oral estrogen?

Estrogen raises thyroid-binding globulin, so more hormone is bound and less is free.

What are three contraindications to systemic estrogen therapy?

Any three of: undiagnosed genital bleeding, breast or estrogen-dependent cancer, active or past DVT/PE, stroke or heart attack, liver disease, thrombophilia, pregnancy.

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