Using the combined oral contraceptive pill

The hormones mainly prevent the release of an egg and also change cervical mucus and the womb lining. Taken correctly, it can make bleeding more predictable and may reduce painful periods; some people use it as part of treatment for irregular periods, endometriosis or polycystic ovary syndrome. It does not protect against sexually transmitted infections. Different pills contain different hormone combinations, so a prescription should match your health history, symptoms and preferences.

Take each tablet according to the pack instructions and ask what to do after a missed pill, vomiting or severe diarrhoea. Tell the prescriber about migraine with aura, previous blood clots, high blood pressure, smoking, liver disease, medicines and recent childbirth. Some medicines and herbal products can affect contraception. Do not borrow another person's prescription. A clinician may check blood pressure and review whether the formulation remains suitable as circumstances change.

Get urgent help for sudden chest pain, breathlessness, coughing blood, one-sided leg swelling or pain, sudden weakness, trouble speaking, or a severe unusual headache or vision change. Contact your prescriber for persistent troublesome symptoms, very high blood pressure readings, suspected pregnancy or repeated missed tablets. Do not restart or change the pill after a serious symptom without medical advice.

Ask which formulation suits you, how to start it, what to do after a missed tablet, whether another medicine interacts with it, and how it fits your goals for bleeding or period pain. Confirm when protection begins and which warning symptoms require urgent help.