How to take a 21-day combined pill

Begin the next pack on the scheduled day even if you are still bleeding. Different brands can have different instructions, so the leaflet supplied with your pill and advice from your prescriber or pharmacist take priority.

The combined pill contains an oestrogen and a progestogen. It mainly prevents ovulation and also changes cervical mucus and the uterine lining. Bleeding during the break is a withdrawal bleed rather than a physiological menstrual period.

When started and taken correctly, contraception continues through the scheduled break. Starting late, extending the break, missing active pills, vomiting soon after a dose or having severe diarrhoea can reduce protection. Some medicines and herbal products can also interfere with effectiveness.

Choose a consistent daily time and keep the next pack available before the current one ends. If you miss a pill, check your brand leaflet or contact a pharmacist promptly; the correct action depends on how many pills were missed and where you are in the pack. You may need condoms or emergency contraception, but do not guess which applies.

Tell a clinician that you use a combined pill before starting new medicines. Blood pressure and personal risk factors should be reviewed periodically. The pill does not protect against sexually transmitted infections, for which condoms provide additional protection.

Seek urgent medical care for sudden breathlessness, chest pain, coughing blood, painful swelling in one leg, sudden weakness or numbness, difficulty speaking, a new severe headache, major vision change, or severe upper abdominal pain. Arrange a medication review if migraine with aura begins, bleeding is persistently troublesome, or you think you may be pregnant.

Ask whether your medical history, blood pressure, migraines, smoking status and current medicines make this pill suitable. Clarify when protection begins, what your specific brand requires after a missed pill, and what to do if vomiting or diarrhoea affects a dose.