How does combined pill work?

The combined pill uses oestrogen and progestogen to prevent ovulation and make sperm movement into the womb more difficult. It also changes the womb lining, reducing the chance that a fertilised egg could attach. Taken as directed, it provides ongoing contraception, but it does not protect against sexually transmitted infections.

The hormones mainly suppress the monthly release of an egg. Different formulations contain different progestogens; some use levonorgestrel, described in [Levonorgestrel](/materials/levonorgestrel/). Bleeding during a break or inactive-tablet phase is a withdrawal bleed rather than evidence that ovulation has occurred.

Some people notice lighter or more predictable bleeding, and clinicians may prescribe the combined pill to help hormone-related symptoms linked with [Endometriosis](/conditions/endometriosis/), [Polycystic Ovary Syndrome](/conditions/polycystic-ovary-syndrome/) or painful periods. Suitability depends on your medical history, blood pressure, smoking status, migraine pattern and other medicines.

Take one tablet at the same time each day according to the pack instructions. If you miss tablets, vomit soon after taking one or have severe diarrhoea, follow the product leaflet or ask a pharmacist because extra contraception may be needed. Tell the prescriber about medicines and supplements before starting. A [Vaginal Ring](/treatments/contraception-and-family-planning/vaginal-ring/) is another combined hormonal option.

Get urgent medical help for sudden chest pain, breathlessness, coughing blood, one-sided leg swelling or pain, sudden weakness, trouble speaking, or a severe unusual headache. Contact your prescriber for persistent troublesome bleeding, mood changes or symptoms that make you question whether the method suits you.

Ask which formulation fits your history, how to start the pack, what to do after missed tablets, whether your migraines or medicines affect safety, and what alternatives are available if daily tablets are difficult.