Ethinylestradiol

How it works

Combined with a progestogen, it suppresses the hypothalamic-pituitary axis to inhibit ovulation, and also thickens cervical mucus and alters the endometrium.

Prescribing in practice

• It increases the risk of venous thromboembolism (higher with certain progestogens, smoking, obesity and immobility) and carries a small arterial risk of stroke and myocardial infarction.
• It is contraindicated in migraine with aura and in other high-risk situations, so assess cardiovascular and thrombotic risk factors before prescribing.
• Enzyme-inducing drugs reduce contraceptive efficacy, so an alternative or additional method may be needed.

Monitoring

Check blood pressure and reassess risk factors before starting and at review; reassess promptly if new migraine with aura, significant blood pressure rise or other risk factors develop.

Counselling the patient

• Seek urgent help for symptoms of a clot, such as calf pain or swelling, breathlessness or chest pain.
• Tell your prescriber if you develop new migraines, especially with aura, visual disturbance or weakness.
• Let healthcare staff know you take it before planned surgery or periods of immobility, and tell your prescriber about any new medicines.

Evidence & guidelines

Standard combined hormonal contraceptive oestrogen (FSRH; NICE CKS).