Estrogen·Endocrinology - Women's Health

Ethinylestradiol

Contraception, severe dysmenorrhoea, heavy menstrual bleeding, acne, endometriosis

PBSHORMONELevlen, Microgynon, Yaz, Yasmin, Brenda (All in combination with various progestins).Tablets (typically 20, 30, o…S4+1

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At a glance

Dose

20-35 mcg/day

Half-life

10-27 h

High risk: VTE Risk

CRITICAL

High risk: Migraine Aura

CONTRAIND.

Cautions

Avoid / Cautions

Current/past VTE or arterial thrombosis, migraine with aura, smoking age >35, severe/uncontrolled hypertension, breast cancer or suspected sex-steroid malignancy, active/severe liver disease, pregnancy, and major surgery/prolonged immobilisation. Combined hormonal contraception can reduce breast milk supply.

Where it stands

Rapid Summary

Overview

Highly potent synthetic estrogen. The primary estrogenic component of almost all Combined Oral Contraceptive Pills (COCPs). Suppresses ovulation and stabilizes the endometrium.

Clinical Focus

Combined hormonal contraception increases venous and arterial thrombotic risk; screen for aura migraine, smoking age >35, hypertension, VTE history, breast cancer, severe liver disease, and immobilisation risk before prescribing.

Bottom Line

Ethinylestradiol is the standard oestrogen component in combined oral contraceptives, but significantly increases VTE risk especially in smokers over 35 and with obesity or immobility.

Formulation & Access

Brand Names

Levlen, Microgynon, Yaz, Yasmin, Brenda (All in combination with various progestins).

Oral Routes

Tablets (typically 20, 30, or 35 micrograms).

Prescribing & PBS

Unrestricted General Benefit (S4).

Indications & Use

Primary

PBSTGA

Contraception, severe dysmenorrhoea, heavy menstrual bleeding, acne, endometriosis.

Clinical Place

The most widely used reversible contraceptive. Non-contraceptive benefits (acne, bleeding control) drive massive prescribing.

Quick reference

Class & Role

Estrogen — Highly potent synthetic estrogen.

Route / Formulation

Tablets (typically 20, 30, or 35 micrograms). (Levlen, Microgynon, Yaz, Yasmin, Brenda (All in combination with various progestins).)

Usual Dose & Max

PO 20-35 mcg OD (Combined with a progestin, taken for 21 days followed by 7 days of sugar pills or skipped for continuous active use). Max 50 mcg/day (Modern COCPs use 20-35 mcg).

Key Indication Doses

Contraception / Dysmenorrhoea: PO 20-35 mcg OD (Combined with a progestin, taken for 21 days followed by 7 days of sugar pills or skipped for continuous active use). Missed Dose Rule: If a pill is < 24h late, take immediately. If > 24h late, take the most recent missed pill, discard older missed pills, and use backup barrier contraception for 7 days.

Best Uses

Ethinylestradiol is the standard oestrogen component in combined oral contraceptives, but significantly increases VTE risk especially in smokers over 35 and with obesity or immobility.

Key Risks

Cardiovascular: Venous Thromboembolism (DVT/PE), arterial thrombosis (Stroke, MI), severe hypertension. Oncology: Slight increase in breast/cervical cancer risk; significant DECREASE in ovarian/endometrial cancer risk. Gastrointestinal: Nausea (estrogen-driven, worse with 35mcg pills). Metabolic: Fluid retention, worsened migraines, melasma (skin darkening).

Key Interactions

Hepatic Enzyme Inducers (Carbamazepine, Phenytoin, Rifampicin, St John's Wort). These completely shred the estrogen in the liver, causing the COCP to fail and leading to unintended pregnancy. Must use alternate contraception (Mirena/Copper IUD). Lamotrigine. Estrogen halves lamotrigine levels. When the patient takes their 7-day sugar pill break, lamotrigine levels double, causing acute neurotoxicity.

Monitoring

Check BP before prescribing and annually. Counsel on the symptoms of a DVT/PE (calf pain, sudden shortness of breath, chest pain). Must be ceased 4 WEEKS prior to major elective surgery to allow clotting factors to normalize and prevent post-op PE.

Clinical Pearl

If a woman says she gets migraines with 'flashing lights or zig-zags' (aura), prescribing the COCP is medical negligence. The estrogen increases her baseline risk of an ischemic stroke by up to 600%. Use a Progestin-Only pill instead.

Access

Levlen, Microgynon, Yaz, Yasmin, Brenda (All in combination with various progestins).Tablets (typically 20, 30, o…

Brand: Levlen, Microgynon, Yaz, Yasmin, Brenda (All in combination with various progestins).
Formulation: Tablets (typically 20, 30, or 35 micrograms).

From this page

No calculator, monitoring schedule or factsheet is linked to this medicine page yet.

Cautions

Avoid / Cautions