The progestogen-only pill (POP)
How effective any contraceptive is depends on how old you are, how often you have sex and whether you follow the instructions.
If 100 sexually active women don't use any contraception, 80 to 90 will become pregnant in a year.
If taken according to instructions the POP is over 99 per cent effective. This means that less than one woman in 100 will get pregnant in a year.
If the POP is not taken according to instructions, more women will become pregnant.
The POP works in a number of ways.
- It mainly works by thickening the mucus from your cervix. This makes it difficult for sperm to move through it and reach an egg.
- It sometimes stops your ovaries releasing an egg (ovulation). This is the main action of one POP, Cerazette. This may mean that Cerazette is more effective than other POPs, but research has not yet confirmed this.
You can go to a contraception or sexual health clinic, or general practice. If you prefer not to go to your own general practice, or if they don’t provide contraceptive services, they can give you information about another practice or clinic. All treatment is free and confidential. You don’t need to have a vaginal or breast examination or cervical screening test when you are first prescribed the POP.
Not everyone can use the POP and a doctor or nurse will ask you about your own and your family's medical history. Do mention any illness or operations you have had. Some of the conditions which may mean you should not use the POP are:
- you think you might already be pregnant
- you take certain medicines.
You have now or have had in the past:
- heart disease or a stroke
- disease of the liver
- systemic lupus erythematosus
- current breast cancer or breast cancer within the last five years.
If you are healthy and there are no medical reasons for you not to take the POP you can take it until your menopause or until you are 55 years.
Some of the advantages of the POP are:
- you can use it if you are breastfeeding
- it is useful if you cannot take estrogens, like those found in the combined pill, contraceptive patch or contraceptive vaginal ring
- you can use it at any age, but it is especially useful if you smoke and are 35 or over
- it may help with premenstrual symptoms and painful periods.
There are no serious side effects with the POP. However:
- You may not have regular periods while you are taking the POP. Your periods may be irregular, light, or more frequent or may stop altogether. This may settle down and is not harmful but you may find it annoying. If you have any concerns see your doctor or nurse. Changing to a different POP may help.
- The POP does not protect you against sexually transmitted infections, so you may need to use condoms as well.
- You have to remember to take the pill at the same time every day.
- You may get some temporary side effects when you first starting taking the POP, these should stop within a few months. They include spotty skin, breast tenderness, weight change and headaches.
The POP is a very safe pill to take but there are some risks.
- Some women may develop small fluid-filled cysts on their ovaries. These are not dangerous and do not usually need to be removed. Often there are no symptoms, but some women may have pelvic pain. These cysts usually disappear without treatment.
- Research about the risk of breast cancer, cervical cancer and hormonal contraception is complex and contradictory. Research suggests that users of all hormonal contraception appear to have a small increase in risk of being diagnosed with breast cancer compared to non-users of hormonal contraception.
You can start the POP anytime in your menstrual cycle if you are sure you are not pregnant.
If you start the POP on the first day of your period you will be protected against pregnancy immediately.
You can also start the POP up to and including the fifth day of your period and you will be protected from pregnancy immediately.
However, if you have a short menstrual cycle with your period coming every 23 days or less, starting the POP as late as the fifth day of your period may not provide you with immediate contraceptive protection. This is because you may ovulate early in your menstrual cycle. You may wish to talk to your doctor or nurse about this and whether you need to use an additional contraceptive method for the first two days.
If you start the POP at any other time in your menstrual cycle use another contraceptive method, such as condoms, for the first two days of pill taking.
The POP can be started any time after the birth. If you start the POP after day 21 you will need to use additional contraception for two days. You can breastfeed while you are taking the POP. A tiny amount of hormone enters your breast milk, but research has shown this will not harm your baby.
You can start taking the POP immediately after a miscarriage or abortion. You will be protected from pregnancy immediately.
When taking your first pill choose a convenient time to take it. This can be anytime of the day.
Once you have chosen a time you must then take one POP each day at this same time until you finish all the pills in the pack.
You then start a new pack the next day so there are no breaks between packs.
For your pill to work it is important not to take it more than three hours (12 hours for Cerazette) after your chosen time. If you remember later than this – see below, What do I do if I miss a pill?.
If you are changing to another POP (or from the combined pill) you may be advised to start the new pill immediately or start the day after you take your last pill. Do not have a break between packs. There is no need to wait for your period. You will then continue to have protection from pregnancy.
If you vomit within two hours of taking the POP, it will not have been absorbed by your body. Take another pill as soon you feel well enough. As long as you are not sick again your contraception will not be affected. Take your next pill at the normal time. If you continue to be sick, seek advice.
If you have very severe diarrhoea that continues for more than 24 hours, this may make the POP less effective. Keep taking your pill at the normal time, but treat each day that you have severe diarrhoea as if you had missed a pill and follow the missed pill instructions below.
If you are given medicines by a doctor, nurse or hospital always say you are taking the POP. Commonly used antibiotics do not affect the POP. Medicines such as some of those used to treat epilepsy, HIV and TB, and the complementary medicine St John’s Wort, may make it less effective. These types of drugs are called enzyme inducers. If you take these medicines, talk to your doctor or nurse about how to take the POP – you may need to use a different method of contraception.
If you are more than three hours late (12 hours if you are taking the POP, Cerazette):
- Take a pill as soon as you remember. If you have missed more than one, only take one.
- li>Take your next pill at the usual time. This may mean taking two pills in one day. This is not harmful.
- You are not protected against pregnancy. Continue to take your pills as usual, but use an additional method of contraception, such as condoms, for the next two days.
If you are less than three hours late (12 hours if you are taking the POP, Cerazette):
- Take a pill as soon as you remember, and take the next one at the usual time. You are protected from pregnancy.
If you took all your pills correctly and you didn't have an upset stomach or take any other medicines which might affect the POP, then it is unlikely you are pregnant. Continue to take your pills as normal. There is no evidence that if you take the POP when you are pregnant it will harm the baby. If you are worried ask your doctor or nurse for advice or do a pregnancy test. Taking the POP does not affect a pregnancy test.
You should seek medical advice as soon as possible if you have a sudden or unusual pain in your lower abdomen or if your period is shorter or lighter than usual. These might be the warning signs of an ectopic pregnancy. An ectopic pregnancy develops outside your uterus, usually in a fallopian tube. Although this is not common, it is dangerous.
You can try to get pregnant as soon as you stop taking the POP. You can stop taking the pill at any time. Ideally you should wait for one natural period before trying to get pregnant, so you will need to use another method of contraception, such as condoms. This means the pregnancy can be dated more accurately and you can start pre-pregnancy care such as taking folic acid and stopping smoking. You can ask your doctor or nurse for advice. Don't worry if you get pregnant sooner, it will not harm the baby.
When you first start the POP you will usually be given three months' supply to see how it suits you. After that you should go back to the doctor or nurse to get new supplies and to have your blood pressure checked. If there are no problems, you can be given up to one year’s supply of pills.
If you are fasting because of a health or medical issue (such as surgery) you should consult your practice nurse or doctor or phone the FPA helpline for advice.
If you are fasting for religious or cultural reasons follow the advice below.
Fasting during certain times of day
Take your pill at a time of day when you can eat. You might need to change your usual time.
If you use Cerazette:
- start taking your pill at a time when you can eat, as long as you do not have to take a pill more than 12 hours late
- if this isn’t possible, follow the advice for the other types of POP.
Other types of POP:
- Before the fasting period begins, take your pill earlier than usual at a time when you know you will be able to eat. For example, if you normally take it at 7am, and this is now a fasting time, take it before you go to bed the night before or earlier.
- Taking two pills in 24 hours is safe and won’t affect your contraceptive cover.
- If you want to change your time to an earlier one go backwards. For example, take your pill at 11pm the first night, 10pm the next night, 9pm the next and so on until you reach a time that suits you.
- Take the rest of your pack at your new time.
- You might get some irregular bleeding but this isn’t harmful.
If taking your pill earlier isn’t possible then start taking it at your new time straight away, even if this is more than three hours late. You will need to use additional contraception (such as a condom) if you have sex during the next two days.
Fasting for 24 hours, NOT MORE than once a month
- If you miss one pill (including Cerazette) you will not be protected against pregnancy.
- Take your next pill as normal the next day.
- Use an additional method of contraception (such as a condom) if you have sex during the next two days.
Fasting for 24 hours, MORE than once a month
If you fast for 24 hours more than once in any month there is a risk that you will lose your protection from pregnancy. You will need to use an additional form of contraception.
If you regularly fast more than once a month a different method of contraception might be more suitable for you.
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This website can only give you general information about contraception. The information is based on evidence-guided research from the World Health Organization and The Faculty of Sexual and Reproductive Healthcare of the Royal College of Obstetricians and Gynaecologists. All methods of contraception come with a Patient Information Leaflet which provides detailed information about the method.
Remember – contact your doctor, practice nurse or a contraception clinic if you are worried or unsure about anything.