Progestogen-only pill

What is it?

The progestogen-only pill (POP) contains a hormone called progestogen. This is similar to the natural hormone progesterone that women produce in their ovaries. There are different types of POP.

How does it work?

• It thickens the mucus in the cervix to stop sperm meeting an egg.
• It makes the lining of the womb thinner, so it's less likely to accept a fertilised egg.
• Sometimes it stops the ovaries from releasing an egg (ovulation) - this is the main action of the POP called Cerazette.

Myths about the progestogen-only pill:

• It's a smaller version of the combined pill. Not true - it's different as it only contains progestogen.
• You can't use common antibiotics with POP. Not true - you can but you can't use enzyme-inducing antibiotics (used for epilepsy, TB or HIV) as they reduce the POP's effectiveness.

How reliable is the progestogen-only pill?

Its effectiveness depends on how carefully it's used. The POP is 99 per cent effective when taken according to instructions. This means that using this method, one woman in 100 will get pregnant in a year.

The POP can be started up to and including the fifth day of a period. If taken at this time it's effective straight away. If started at any other time, additional contraception has to be used for two days.

It needs to be taken at the same time each day and is taken every day until the pack is finished. A new pack is started immediately without any break, which means you'll be taking pills during your period.

Advantages and disadvantages

The advantages of the progestogen-only pill include:

• It doesn’t interrupt sex.
• You can use it while breastfeeding.
• You can use it if you cannot use oestrogens.
• You can use it if you smoke and are 35 and over.
• It may help with painful periods and premenstrual symptoms.

The disadvantages include:

• You must remember to take the pill at the same time each day.

Temporary side-effects at first may include spotty skin and breast tenderness. If these do not stop with a few months, changing the POP might help.

Other side-effects may include:

• Light, more frequent or irregular periods - or they may stop.
• Some women may develop small fluid-filled cysts on their ovaries, these aren't harmful and usually disappear without treatment.
• Possible increase in the risk of being diagnosed with breast cancer.

Other things to consider include:

• Initially, you'll be given a three-month supply and if there are no problems you'll then be given up to a year's supply.
• You don’t need a cervical screening test or an internal examination to have the POP.
• The POP does not protect you against sexually transmitted infections.

Who can use it?

The POP may not be suitable for all women, but for most women the benefits outweigh the possible disadvantages.

It may be unsuitable for you to use the POP if you:

• Think you may already be pregnant.
• Do not want any change to your periods.
• Take certain medicines - always check.
• Have a heart abnormality or circulatory disease.
• Have active liver or gall bladder disease.
• Have breast cancer now or within the past five years.
• Have a history of ovarian cysts.
• Have migraines with aura.

If you forget to take the progestogen-only pill

You've 'missed a pill' if you take it more than three hours later than your chosen time. This is 12 hours later for Cerazette. It's important to take it at the same time every day, but if you forget:

• You won't be protected against pregnancy, so take the pill as soon as you remember and use additional contraception for two days.
• Take your next pill at the usual time - this may mean taking two pills in one day.
• If you're sick within two hours of taking the pill, it will not have been absorbed properly, so take another pill as soon as you feel well enough.
• If you continue to be sick or have severe diarrhoea for more than 24 hours, seek advice.

Where can I get the progestogen-only pill?

The POP is free on the NHS from contraception clinics, sexual health clinics or your GP.

Advice and support

Call the FPA helpline on 0845 122 8690.