The traditional progestogen-only pill (POP) prevents pregnancy by thickening the mucus in the cervix to stop sperm reaching an egg.

The desogestrel progestogen-only pill can also stop ovulation.

The progestogen-only pill needs to be taken every day to work.

At a glance: facts about the progestogen-only pill

• If taken correctly, it's more than 99% effective. This means fewer than 1 in 100 who uses the progestogen-only pill as contraception will get pregnant in 1 year.
• With "typical use" of the progestogen-only pill (the way it's taken by a lot of women in real life), it's only about 91% effective.
• You take a pill every day, with no break between packs of pills.
• The progestogen-only pill can be used if you cannot use contraception that contains oestrogen.
• You can take the progestogen-only pill if you're over 35 and you smoke.
• You must take the progestogen-only pill at the same time each day. If you take it more than 3 hours late (traditional progestogen-only pill) – or 12 hours late (desogestrel pill) – it may not be effective.
• If you're sick (vomit) or have severe diarrhoea, the progestogen-only pill may not work.
• Some medicines may affect the progestogen-only pill's effectiveness – ask your doctor for details.
• Your periods may stop or become lighter, irregular or more frequent.
• Side effects may include spotty skin and breast tenderness – these should clear up within a few months.
• You'll need to use condoms as well as the progestogen-only pill to be protected against sexually transmitted infections (STIs).

How to take the progestogen-only pill

There are 2 different types of progestogen-only pill:

• 3-hour progestogen-only pill (traditional progestogen-only pill) – must be taken within 3 hours of the same time each day
• 12-hour progestogen-only pill (desogestrel progestogen-only pill) – must be taken within 12 hours of the same time each day

Follow the instructions that come with your pill packet – missing pills or taking the pill alongside other medicines can reduce its effectiveness.

There are 28 pills in a pack of progestogen-only pills. You need to take 1 pill every day within either 3 or 12 hours of the same time each day, depending on which type you're taking.

There's no break between packs of pills – when you finish a pack, you start the next one the next day.

Starting the first pack of pills

• 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 the following day – there's no break between packs of pills

You can start the progestogen-only pill at any time in your menstrual cycle.

If you start it on day 1 to 5 of your menstrual cycle (the first 5 days of your period), it'll work straight away and you'll be protected against pregnancy. You will not need additional contraception.

If you have a short menstrual cycle, you'll need additional contraception, such as condoms, until you've taken the pill for 2 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've taken the pill for 2 days.

After having a baby

If you've just had a baby, you can start the progestogen-only pill any time between day 1 and day 21 after the birth. You'll be protected against pregnancy straight away.

If you start the progestogen-only pill more than 21 days after giving birth, use additional contraception such as condoms until you've taken the pill for 2 days.

After a miscarriage or abortion

If you've had a miscarriage or abortion, you can start the progestogen-only pill up to 5 days afterwards and you'll be protected from pregnancy straight away.

If you start the pill more than 5 days after a miscarriage or abortion, use additional contraception until you've taken the pill for 2 days.

What to do if you miss a pill

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

• the type of pill you're taking
• how long ago you missed the pill
• how many pills you've forgotten to take
• whether you've had sex without using another type of contraception in the previous 7 days

If you're less than 3 or less than 12 hours late taking the pill

If you're taking a 3-hour progestogen-only pill and are less than 3 hours late taking it, or if you're taking the 12-hour progestogen-only pill and are less than 12 hours late:

• take the late pill as soon as you remember, and
• take the remaining pills as normal, even if that means taking 2 pills on the same day

The pill will still work, and you'll be protected against pregnancy – you do not need to use additional contraception.

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

If you're more than 3 or more than 12 hours late taking the pill

If you're taking a 3-hour progestogen-only pill and are more than 3 hours late taking it, or you're taking the 12-hour progestogen-only pill and are more than 12 hours late, you will not be protected against pregnancy.

What you should do:

• take a pill as soon as you remember – only take 1, even if you've missed more than 1 pill
• take the next pill at the usual time – this may mean taking 2 pills on the same day (1 when you remember and 1 at the usual time); this is not harmful
• carry on taking your remaining pills each day at the usual time
• use extra contraception such as condoms for the next 2 days (48 hours) after you remember to take your missed pill, or do not have sex
• if you have unprotected sex from the time that you miss your pill until 2 days after you start taking it reliably again, you may need emergency contraception – get advice from your contraception clinic or GP
• tell them that you've been taking the progestogen-only pill as this can affect which emergency contraception is best for you to take

It takes 2 days for the progestogen-only pill to thicken cervical mucus so sperm cannot get through or survive.

The Faculty of Sexual Health and Reproductive Healthcare recommends using extra contraception for 2 days after you remember to take your pill.

The patient information leaflet that comes with your pill might say to use condoms for the next 7 days after you remember to take your pill. This is because it takes 7 days for the pill to stop you ovulating.

Sickness and diarrhoea

If you're sick (vomit) within 2 hours of taking a progestogen-only 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 you do not take another pill within 3 (or 12 hours) of your normal time, use additional contraception, such as condoms, for 2 days (7 days for the 12-hour pill).

If you continue to be sick, keep using another form of contraception, such as condoms, while you're ill and for 2 days after recovering.

Very severe diarrhoea – 6 to 8 watery poos in 24 hours – may also mean that the pill does not work properly.

Keep taking your pill as normal, but use additional contraception, such as condoms, while you have diarrhoea and for 2 days after recovering, or 7 days if you're taking a 12-hour pill.

Speak to a pharmacist, nurse or GP, or call NHS 111 if you're unsure whether you're protected against pregnancy, or if your sickness or diarrhoea continues.

Who can use the progestogen-only pill?

You should be able to use the progestogen-only pill, but you may not be able to if you:

• think you might be pregnant
• do not want your periods to change
• take other medicines that may affect the pill
• have unexplained bleeding in between periods or after sex
• have developed arterial disease or heart disease or have had a stroke
• have liver disease
• have breast cancer or have had it in the past
• have severe cirrhosis or liver tumours

If you're 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're 55.

Breastfeeding

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

Pregnancy

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

If this happens, there's 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 contraception clinic.

Get medical advice if you have a sudden or unusual pain in your tummy, or if your period is much shorter or lighter than usual.

It's possible that these are warning signs of an ectopic pregnancy, although this is rare.

Advantages and disadvantages

Advantages:

• it does not interrupt sex
• you can use it when breastfeeding
• it's useful if you cannot take the hormone oestrogen, which is in the combined pill, contraceptive patch and vaginal ring
• you can use it at any age

Disadvantages:

• you may not have regular periods while taking it – your periods may be lighter, more frequent, or may stop altogether, and you may get spotting between periods
• it does not protect you against STIs
• you need to remember to take it at or around the same time every day
• some medicines, including some (uncommon) antibiotics, can make it less effective

Side effects

The progestogen-only pill is generally well tolerated and side effects are rare.

Some side effects include: 

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

These side effects are most likely to occur during the first few 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 GP or practice nurse. They may advise you to change to another pill or a different form of contraception.

The progestogen-only pill with other medicines

When you take 2 or more medicines at the same time, they can sometimes interact with each other.

Some medicines interact with the progestogen-only pill, which can stop it working properly.

If you want to check whether your medicines are safe to take with the progestogen-only pill, you can: 

• ask your GP, practice nurse or pharmacist
• read the patient information leaflet that comes with your medicine

Ovarian cysts

There is a chance you could develop fluid-filled cysts on your ovaries. These are not dangerous and do not usually need to be removed.

The cysts usually disappear without treatment. In many cases, the cysts do not cause symptoms, although you may experience pelvic pain.

Breast cancer

Research is continuing into the link between breast cancer and the progestogen-only pill.

There is not enough evidence to say for certain that the progestogen-only pill does not increase the risk of breast cancer.

But if there is any increased risk, it's likely to be very small and disappear with time after you stop taking the progestogen-only pill.

Where you can get the progestogen-only pill

You can get contraception for free, even if you're under 16, from:

• contraception clinics
• sexual health clinics
• some GP surgeries
• some young people's services
• pharmacies

How do I change to a different pill?

If you want advice about changing your contraceptive pill, you can visit your GP, contraceptive nurse (sometimes called a family planning nurse), sexual health clinic or pharmacist.

You should not have a break between different packs, so you will usually be advised to start the new pill immediately or wait until the day after you take the last of your old pills.

You may also be advised to use alternative methods of contraception during the changeover, as the new pill may take a short time to take effect.

If you're under 16 years old

Contraception services are free and confidential, including for people under the age of 16.

If you're under 16 and want contraception, the doctor, nurse or pharmacist will not tell your parents (or carer) as long as they believe you fully understand the information you're given, and your decisions.

Doctors and nurses work under strict guidelines when dealing with young people under 16. They'll encourage you to consider telling your parents, but they will not make you.

The only time a professional might want to tell someone else is if they believe you're at risk of harm, such as abuse. The risk would need to be serious, and they would usually discuss this with you first.