The combined oral contraceptive pill is usually just called the pill. It contains synthetic (artificial) versions of the female hormones oestrogen and progesterone, which women produce naturally in their ovaries.
The pill is usually taken to prevent pregnancy, but it can also be used to treat:
How effective is it?
When taken correctly, the pill is over 99% effective at preventing pregnancy. This means that less than 1 woman in every 100 will get pregnant in a year.
How the pill works
The pill prevents the ovaries from releasing an egg each month (ovulation). It also:
- thickens the mucus in the neck of the womb, so it is harder for sperm to penetrate the womb and reach an egg
- thins the lining of the womb, so there is less chance of a fertilised egg implanting into the womb and being able to grow
Types of combined pill
Although there are many different brands of pill, there are three main types:
- Monophasic 21-day pills (the most common type). Each pill has the same amount of hormone in it. One pill is taken each day for 21 days and then no pills are taken for the next seven days. Examples are Microgynon, Brevinor and Cilest.
- Phasic 21-day pills. Phasic pills contain two or three sections of different coloured pills in a pack. Each section contains a different amount of hormones. One pill is taken each day for 21 days and then no pills are taken for the next seven days. Phasic pills need to be taken in the right order. Examples are Binovum and Logynon.
- Every Day (ED) pills. There are 21 active pills and 7 inactive (dummy) pills in a pack. The two types of pill look different. One pill is taken each day for 28 days with no break between packets of pills. Every Day pills need to be taken in the right order. Examples are Microgynon ED and Logynon ED.