Introduction of progestogen-only pill

The progestogen-only contraceptive pill is taken by women to prevent pregnancy.

It contains progestogen, a synthetic (artificial) version of the hormone progesterone that women produce naturally in their ovaries.

The progestogen-only pill differs from the combined contraceptive pill, which contains both female sex hormones oestrogen and progestogen. This makes the progestogen-only pill an option for women who cannot take the combined contraceptive pill, such as those over the age of 35 and who smoke, or those who are very overweight.

One pack of the progestogen-only pill contains 28 pills. One pill is taken every day of the menstrual cycle.

Who can take it?

The progestogen-only pill can be used by most women.

But you may not be able to take it if you have had certain health conditions, including heart disease, breast cancer, or an ectopic pregnancy.

Learn more in special considerations for the progestogen-only pill.

How effective is it?

When taken correctly, the progestogen-only pill is more than 99% effective at preventing pregnancy. This means that less than one woman in every 100 who take the pill will get pregnant in a year.

How the progestogen-only pill works

The progestogen-only pill works in two ways:

  • it thickens the mucus in the neck of the womb, so it is harder for sperm to penetrate into the womb and reach an egg
  • it thins the lining of the womb, so there is less chance of a fertilised egg implanting into the womb and being able to grow

Sometimes, the progestogen-only pill may also prevent ovulation (the release of an egg from your ovaries each month).

Side effects of progestogen-only pill

Side effects with the progestogen-only pill are rare.

You may experience irregular menstrual bleeding. Other possible side effects include:

  • acne
  • breast tenderness and breast enlargement
  • mood changes

Learn more in side effects of the progestogen-only pill and risks of the progestogen-only pill.

Types of progestogen-only pill

There are two different types of progestogen-only pill, which must be taken at different times of the day:

  • The three-hour progestogen-only pill must be taken within three hours of the same time each day. Examples are Femulen, Micronor, Norgeston and Noriday.
  • The 12-hour progestogen-only pill (Cerazette) must be taken within 12 hours of the same time each day. It is less commonly used than the three-hour pill.

Learn more in how to take the progestogen-only pill

It is important to follow instructions that come with the packet of the progestogen-only pill, because missing pills or taking the pill alongside other medicines can reduce its effectiveness. Learn more in missed progestogen-only pill and progestogen only pill – interactions.

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