Why is ethinylestradiol used in the combined pill?

The combined pill contains ethinylestradiol together with a progestogen. This combination changes the normal hormone signals that lead to ovulation. It also thickens cervical mucus, making sperm movement more difficult, and changes the womb lining. Ethinylestradiol can help provide a predictable withdrawal bleed during the pill-free or inactive-tablet interval, although bleeding patterns vary.

Different combined pills contain different progestogens and oestrogen doses. Ethinylestradiol is not suitable for everyone because oestrogen-containing contraception can increase the risk of blood clots and may be unsafe with certain medical conditions or medicines.

Before starting, tell the prescriber about migraine with aura, previous blood clots, high blood pressure, smoking, liver disease, recent childbirth, breastfeeding, and medicines or supplements. Take the pill according to its packet instructions and ask what to do after a missed tablet or vomiting. Some medicines can reduce contraceptive protection, so check before starting a new treatment.

The combined pill does not protect against sexually transmitted infections. Condoms may be appropriate when infection protection is needed.

Seek urgent medical care for sudden chest pain, breathlessness, coughing blood, one-sided leg swelling or pain, sudden weakness, difficulty speaking, or a severe unusual headache. Contact your prescriber about persistent troublesome side effects, very high blood pressure readings, or bleeding that does not settle.

Ask whether an oestrogen-containing pill is suitable for you, how ethinylestradiol differs from other oestrogens, what to do after missed pills, and which warning symptoms require urgent help.