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Progestogen-only contraceptive pill (POP)

Introduction

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 or those who smoke.

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

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 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).

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.

Where you can get the progestogen-only pill

You can get the progestogen-only pill from your GP, local sexual health (genito-urinary medicine or GUM) clinic or contraception clinic. Contraception is free for women and men of all ages through the NHS.

Go to the Local Services search to find sexual health services and GPs in your area.

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Considerations

Special considerations 

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

When to avoid it

You may not be able to use the progestogen-only pill if you have had:

  • heart disease
  • liver disease
  • breast cancer
  • cysts on your ovaries
  • unexplained vaginal bleeding
  • migraines with aura
  • an ectopic pregnancy (when a fertilised egg begins to develop outside the womb)

If you are healthy and there are no medical reasons why you should not take the progestogen-only pill, you can take it until your menopause or until you are 55.

Breastfeeding

The progestogen-only pill is safe to use if you are breastfeeding. Small amounts of progestogen may pass into your breast milk, but this is not harmful to your baby. The progestogen-only pill does not affect the way your breast milk is produced.

Pregnancy

Although it is very unlikely, there is a very small chance that you could become pregnant while taking the progestogen-only pill.

If this happens, there is no evidence that the pill will harm your unborn baby. If you think you may be pregnant, speak to your GP or visit your local family planning clinic.

Get medical advice if you have a sudden or unusual pain in your abdomen (tummy), or if your period is much shorter or lighter than usual. It is possible that these symptoms are warning signs of an ectopic pregnancy, although this is rare.

Advantages

Some advantages of the progestogen-only pill include:

  • it does not interrupt sex
  • you can use it when breastfeeding
  • it is useful if you cannot take the hormone oestrogen, found in the combined pill, contraceptive patch and vaginal ring
  • you can use it at any age: even if you smoke and are over 35
  • it can reduce the symptoms of premenstrual syndrome and painful periods

Disadvantages

Some disadvantages of the progestogen-only pill include:

  • It can cause temporary side effects at first, such as headaches, nausea, breast tenderness and mood swings. If these do not go after a few months, it may help to change to a different pill.
  • You may not have regular periods while taking it. Your periods may be lighter, more frequent or may stop altogether.
  • It does not protect you against sexually transmitted infections.
  • You need to remember to take it at the same time every day.  
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How does it work?

There are 28 pills in a pack of progestogen-only pills. You need to take one pill every day, within either three or twelve hours of the same time each day (depending on which type you are taking).

Starting the first pack of pills

The progestogen-only pill can be started at any time in your menstrual cycle.

It is usually started on the first day of your period (day one of your menstrual cycle). In this case, you will be protected from pregnancy straight away and will not need additional contraception.

You can also start the progestogen-only pill up to, and including, the fifth day of your period and will be protected from pregnancy straight away unless you have a short menstrual cycle (your period is every 23 days or less). If you have a short menstrual cycle, you will need additional contraception, such as condoms, until you have taken the pill for two days.

If you start the progestogen-only pill on any other day of your cycle, you will not be protected from pregnancy straight away and will need additional contraception until you have taken the pill for two days.

After having a baby

If you have just had a baby, the progestogen-only pill can be started on day 21 after the birth. You will be protected against pregnancy straight away.

If you start the progestogen-only pill later than 21 days after giving birth, you will need to use additional contraception (such as condoms) until you have taken the pill for two days.

After a miscarriage or abortion

If you have had a miscarriage or abortion, the progestogen-only pill can be started up to seven days afterwards and you will be protected from pregnancy straight away.

If you start the pill more than seven days after the miscarriage or abortion, use additional contraception until you have taken the pill for two days.

How to take the pill

  • Choose a convenient time in the day to take your first pill.
  • Continue to take a pill at the same time each day until the pack is finished.
  • Start your next pack of pills immediately. There is no break between packs of pills.

Vomiting and diarrhoea

If you vomit within two hours of taking a pill, it may not have been fully absorbed into your bloodstream. Take another pill straight away and the next pill at your usual time.

If the replacement pill is not taken within three hours (12 hours for the 12-hour pill) of your normal time, use additional contraception, such as condoms, for two days.

If you continue to be sick, keep using another form of contraception while you are ill and for two days after recovering.

Very severe diarrhoea (six to eight watery stools in 24 hours) may also reduce the effectiveness of the pill. Keep taking your pill as normal, but use additional contraception, such as condoms, while you have diarrhoea and for two days after recovering.

Speak to your GP or family planning nurse or call NHS Direct Wales if you are unsure whether or not you are protected (0845 46 47), or if your sickness or diarrhoea continues.

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Side effects

The progestogen-only pill is generally well tolerated and side effects are rare. It will not affect your ability to drive or react with any food or alcohol that you consume.

However, you may experience irregular menstrual bleeding, such as:

  • periods that are heavier than usual
  • a missed period
  • breakthrough bleeding and spotting

Some of the other possible side effects of the progestogen-only pill are:

  • acne
  • breast tenderness and breast enlargement
  • an increased or decreased libido (sex drive)
  • mood changes
  • headache and migraine
  • nausea or vomiting
  • cysts (small fluid-filled sacs) on your ovaries (these are usually harmless and disappear without treatment)
  • stomach upset
  • weight gain

These side effects are most likely to occur during the early months of taking the progestogen-only pill, but they generally improve over time and should stop within a few months.

If you have any concerns about your contraceptive pill, see your doctor or nurse. They may advise you to change to another pill or a different form of contraception.

Reporting side effects

The Yellow Card Scheme allows you to report suspected side effects from any type of medicine that you are taking. It is run by a medicines safety watchdog called the Medicines and Healthcare products Regulatory Agency (MHRA). See the Yellow Card Scheme website for more information.

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Interactions other medicines

The progestogen-only pill can interact with other medicines. Some of the more common interactions are listed below. However, this is not a complete list.

If you want to check that your medicines are safe to take with the progestogen-only pill, ask your doctor or pharmacist, or read the patient information leaflet that comes with your medicine.

Antibiotics

The antibiotics rifampicin and rifabutin can reduce the effectiveness of the progestogen-only pill. The other antibiotics do not have this effect.

If you are prescribed rifampicin or rifabutin, you may need to use additional contraception (such as condoms) while you are taking the antibiotic. Speak to your doctor or nurse for advice.

Other medicines

The progestogen-only pill can interact with medicines called enzyme inducers. These speed up how quickly your liver breaks down the hormone progestogen, reducing the effectiveness of the progestogen-only pill.

Examples are:

  • the epilepsy drugs carbamazepine, oxcarbazepine, phenytoin, phenobarbital, primidone and topiramate
  • St John’s Wort (a herbal remedy)
  • antiretroviral medicines used to treat HIV (research suggests that interactions between these medicines and the progestogen-only pill can affect the safety and effectiveness of both)

Your GP or nurse may advise you to use an alternative or additional form of contraception while you are taking any of these medicines.

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Missed pills

If you forget to take a progestogen-only pill, what you should do depends on:

  • the type of pill you are taking
  • how late you are taking the pill and how many pills you have forgotten to take
  • whether you have had sex without using another form of contraception during the previous seven days

If you are less than 3-12 hours late

If you are taking a three-hour progestogen-only pill and you are less than three hours late taking it, or you are taking the 12-hour progestogen-only pill and are less than 12 hours late, you do not need to worry.

Take the late pill as soon as you remember and the remaining pills as normal. Your contraceptive protection will not be affected, so you do not need to use any additional contraception.

Do not worry if you have had sex without using another form of contraception. You do not need emergency contraception.

If you are more than 3-12 hours late

If you are taking a three-hour progestogen-only pill and you are more than three hours late taking it, or you are taking the 12-hour progestogen-only pill and are more than 12 hours late, follow the advice below:

  • take the last pill you missed straight away (if you have missed more than one, take only one)
  • take your next pill at the normal time.

Depending on when you remember, it may mean taking two pills on the same day (one at the time of remembering and one at the regular time), or even at the same time.

You will not be protected from pregnancy, so use additional contraception, such as condoms, for the next two days after taking the missed pill.

If you have recently had unprotected sex, you may need emergency contraception. Seek advice straight away from your GP or local sexual health clinic. You can also call NHS Direct Wales on 0845 46 47 (24 hours) or the FPA helpline on 0845 122 8690.

The progestogen-only pill is less effective when…

  • it is not taken according to the instructions
  • it does not stay in the body long enough to work, for example because of vomiting or diarrhoea
  • other medicines make it less effective
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Cautions

Cautions

As with the combined contraceptive pill, there are certain risk factors when you use a hormonal contraceptive, such as the progestogen-only pill.

Taking the progestogen-only pill can increase your risk of developing some conditions. These risk factors are detailed below.

Breast Cancer

The progestogen-only pill increases your chances of getting breast cancer, but only very slightly. Once you stop taking the pill, your risk of breast cancer slowly goes back to normal.

The most important risk factor for breast cancer is your age when you stop taking the progestogen-only pill. The older you are when you stop, the slightly higher the risk of developing breast cancer.

For example, for women who stop taking the progestogen-only pill by the age of 30, after taking it for five years, there are 2-3 more cases of breast cancer per 10,000 women.

This is in addition to the expected 44 cases of breast cancer per 10,000 women in this age group if the progestogen-only pill had never been taken.

For women who stop taking the progestogen-only pill by the age of 40, after five years of taking it, there are 10 more cases of breast cancer per 10,000 women.

Again, there would already be an expected 160 cases of breast cancer per 10,000 women in this age group if the progestogen-only pill had never been taken.

When you stop taking the progestogen-only pill, your risk of breast cancer reduces. After ten years, your risk is the same as if you had never taken the progestogen-only pill.

Deep vein thrombosis (DVT)

Taking the progestogen-only pill does not increase your risk of deep vein thrombosis (blood clots in the leg).

However, if you are travelling and will be immobile for long periods, such as on flights over five hours long, you should take precautions to prevent a DVT. Remember to:

  • drink plenty of water,
  • avoid alcohol, as it can lead to dehydration,
  • do simple leg exercises, such as regularly flexing your ankles, and
  • take short walks whenever possible.
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Q&A

Will antibiotics stop my contraception working?

It depends on which type of contraception you’re using. 

It’s now thought the only types of antibiotic that interact with hormonal contraception and make it less effective are rifampicin and rifabutin.

Interactions

When you take two or more medicines at the same time, the effects of one medicine can be altered by the other. This is known as an interaction. Some antibiotics can interact with some forms of hormonal contraception. 

Hormonal contraception

There are several types of hormonal contraception, such as: 

  • combined contraceptive pill 
  • progestogen-only contraceptive pill 
  • contraceptive implants and injections 
  • intrauterine system (IUS) 
  • contraceptive patch 
  • vaginal ring 
  • emergency contraception 

If you’re using hormonal contraception, it’s important to understand that some medicines can reduce its effectiveness. This includes some types of antibiotic. If this happens, to avoid getting pregnant you’ll need to use additional contraception, such as condoms, change to a different method of contraception, or take your contraception in a different way. See below for more details.

If you’re not sure if your contraception is affected by other medicines, speak to your GP or pharmacist or call NHS Direct Wales on 0845 4647.

Antibiotics

Rifampicin-like medicines are the only types of antibiotic that can make hormonal contraception less effective. This includes:

  • rifampicin
  • rifabutin

These types of medicine can increase the enzymes in your body. This is known as enzyme-inducing and can affect hormonal contraception.

Enzymes are proteins that control your body’s chemical reactions. Enzyme-inducing antibiotics speed up the processing of some contraceptive hormones and therefore reduce the levels of these hormones in your bloodstream. This makes the contraceptive less effective.

Apart from those mentioned above, all other antibiotics are not enzyme-inducing.

Additional contraception

If you’re going to take rifampicin or rifabutin for over two months, you may want to consider starting or changing to a contraception method that’s not affected by these medicines if you’re currently using the: 

  • combined pill 
  • progestogen-only pill
  • implant
  • patch 
  • vaginal ring

Contraception methods that aren’t affected by rifampicin or rifabutin include:

  • progestogen injection
  • intrauterine device (IUD) 
  • IUS

If you’re taking rifampicin or rifabutin for less than two months and want to continue your same hormonal contraception, you must discuss this with your doctor. You may be asked to take this contraception in a different way from usual and use condoms as well. You will need to continue this for 28 days after finishing the antibiotics.

If you’re taking antibiotics other than rifampicin or rifabutin, you don’t normally need to use additional contraception.

However, if the antibiotics, or the illness they are treating, cause diarrhoea or vomiting, your oral hormonal contraception may be affected. 

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