When taken correctly, the pill is over 99% effective at preventing pregnancy. This means that less than 1 in 100 women who take the pill will get pregnant in a year.
Who can take it?
Not all women can take the pill. For example, you should not take it if you are pregnant, or if you smoke and are aged 35 or older.
Although there are many different brands of pill, there are three main types:
Monophasic 21-day pills (the most common type). Each pill has the same amount of hormone in it. One pill is taken each day for 21 days and then no pills are taken for the next seven days. Examples are Microgynon, Brevinor and Cilest.
Phasic 21-day pills. Phasic pills contain two or three sections of different coloured pills in a pack. Each section contains a different amount of hormones. One pill is taken each day for 21 days and then no pills are taken for the next seven days. Phasic pills need to be taken in the right order. Examples are Binovum and Logynon.
Every Day (ED) pills. There are 21 active pills and 7 inactive (dummy) pills in a pack. The two types of pill look different. One pill is taken each day for 28 days with no break between packets of pills. Every Day pills need to be taken in the right order. Examples are Microgynon ED and Logynon ED.
It's important to take the pills as instructed, as missing pills, or taking them at the same time as certain medicines may make them less effective. Read more about what to do if you miss a pill and the pill - interactions.
Risks and side effects
There are risks associated with using the combined contraceptive pill, such as blood clots, although they are not common. For most women, the benefits of the pill far outweigh the risks.
Not everyone can use the combined oral contraceptive pill (the pill).
As long as there are no medical reasons why you cannot take the pill and you do not smoke, you can take the pill until your menopause. However, the pill is not suitable for all women.
To find out whether the pill is right for you, talk to your GP, practice nurse or pharmacist.
When to avoid it
You should not take the pill if you:
are pregnant
smoke and are 35 or older
stopped smoking less than a year ago and are 35 or older
are very overweight
take certain medicines (ask your GP about this)
You should also not take the pill if you have (or have had):
thrombosis (a blood clot)
a heart abnormality or heart disease, including high blood pressure
diabetes with complications or diabetes for the last 20 years
Advantages
Some advantages of the pill include:
It does not interrupt sex.
It usually makes your periods regular, lighter and less painful.
It reduces your risk of cancer of the ovaries, womb and colon.
It can reduce symptoms of premenstrual syndrome.
It can sometimes reduce acne.
It may protect against pelvic inflammatory disease.
It may reduce the risk of fibroids, ovarian cysts and non-cancerous breast disease.
Disadvantages
Some disadvantages of the 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.
It can increase your blood pressure.
It does not protect you against sexually transmitted infections.
Breakthrough bleeding and spotting is common in the first few months of using the pill.
Most women can start the pill at any time in their menstrual cycle. But there is special guidance if you have just had a baby, an abortion or a miscarriage.
You may need to use additional contraception during your first days on the pill: this depends on when in your menstrual cycle you start taking it.
Starting the first pack of pills
The combined oral contraceptive pill (the 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.
If you start the pill at any time up to and including the fifth day of your period, you will still 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 seven days.
If you start the 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 seven days.
After having a baby
If you have just had a baby and are not breastfeeding, the pill can be started on day 21 after the birth. You will be protected against pregnancy straight away.
If you start the pill later than 21 days after giving birth, you will need additional contraception (such as condoms) for the next seven days.
If you are breastfeeding a baby under six months old, taking the pill can reduce your flow of milk. It is recommended that you use a different method of contraception until you stop breastfeeding.
After a miscarriage or abortion
If you have had a miscarriage or abortion, the pill can be started up to seven days after this and you will be protected from pregnancy straight away. If started more than seven days after the miscarriage or abortion, use additional contraception until you have taken the pill for seven days.
How to take the pill
Follow the instructions that come with your packet. If you have any questions about how to take the pill, ask your GP, practice nurse or pharmacist.
21-day pills
Take your first pill from the packet marked with the correct day of the week, or the first pill of the first colour (phasic pills).
Continue to take a pill at the same time each day until the pack is finished.
Stop taking pills for seven days (during these seven days you will get a bleed).
Start your next pack of pills on the eighth day, whether you are still bleeding or not. This should be the same day of the week as when you took your first pill.
Every day pills
Take the first pill from the section of the packet marked 'start'. This will be an active pill.
Continue to take a pill every day, in the correct order and preferably at the same time each day, until the pack is finished (28 days).
During the seven days of taking the inactive pills, you will get a bleed.
Start your next pack of pills after you have finished the first, whether you are still bleeding or not.
For monophasic combined pills (pills all the same colour and with the same level of hormones), it is normally fine to start a new pack of pills straight after your last one, for example if you want to delay your period for a holiday.
However, avoid taking more than two packs together unless advised to by your GP. This is because the womb lining continues to build up and you may have breakthrough bleeding as it sheds slightly. Also, some women find they feel very bloated if they run several packs of the pill together.
Side effects of the pill
The combined oral contraceptive pill (the pill) is generally well tolerated, but there are possible side effects.
Breakthrough bleeding and spotting is common in the first few months of taking the pill.
Other temporary side effects may occur after first starting the pill, including:
breast tenderness and breast enlargement
mood changes
an increased or decreased libido (sex drive)
fluid retention
headaches
nausea
rise in blood pressure
If these do not stop within a few months, changing the type of pill may help.
There is no evidence that the pill causes women to gain weight.
If you are taking the pill and concerned about side effects, speak to your GP or practice nurse.
Interactions with other medicines
The combined contraceptive pill (the pill) can interact with other medicines.
Some common interactions are listed below. However, this is not a comprehensive list.
If you want to check your medicines are safe to take with the pill, ask your doctor or pharmacist, or read the patient information leaflet that comes with your medicine.
Antibiotics
The following antibiotics reduce the effectiveness of the pill:
rifampicin
rifabutin
Rifampicin is used to treat conditions such as tuberculosis, and can be prescribed for several months at a time. The antibiotics prescribed for some common conditions, such as acne, do not usually affect the contraceptive pill, but ask your GP if you are unsure.
Long-term rifampicin or rifabutin
If you are going to be taking rifampicin or rifabutin for more than two months, you may want to consider starting or changing to a contraception method that is not affected by these medicines. For example:
If you are taking rifampicin or rifabutin for less than two months and want to continue with your same combined contraceptive pill, you must discuss this with your doctor or specialist nurse. They will be able to get detailed up-to-date guidance from the Faculty of Sexual and Reproductive Healthcare.
You may need additional contraception (such as condoms) while taking the antibiotics and for 28 days after finishing the course. You may also need to change to a higher strength pill and take your pill in a different way from usual. You will need to continue this for 28 days after finishing the course.
Your GP will be able to give you further advice.
Other medicines
The pill can interact with medicines called enzyme inducers, which reduce it's effectiveness.
Examples of enzyme enducers include:
the epilepsy drugs carbamazepine, oxcarbazepine, phenytoin, phenobarbital, primidone and topiramate
St John's wort (a herbal remedy)
antiretroviral medicines used to treat HIV
Your GP or nurse may advise an alternative or additional form of contraception while you are taking one of these medicines.
Missed doses
Missing pills or starting a pack late can make the pill less effective at preventing pregnancy.
Missed pills
The chance of getting pregnant after missing a pill, or pills, depends on:
when the pills are missed
how many pills are missed
A pill is late when you have forgotten to take it at your usual time. You have missed a pill when it is more than 24 hours since the time you should have taken it.
Missing one pill anywhere in your pack or starting the new pack one day late isn't a problem as you will still be protected against pregnancy (known as having contraceptive cover).
However, missing two or more pills or starting the pack two or more days late (more than 48 hours late) may affect your contraceptive cover.
In particular, if you make the seven-day pill-free break longer by forgetting two or more pills, your ovaries might release an egg and there is a risk of getting pregnant. This is because your ovaries are not getting any effect from the pill during the seven-day break.
What to do if you miss a pill or pills
Follow the advice below. If you are not sure what to do, continue to take your pill and use another method of contraception, such as condoms, and seek advice as soon as possible.
If you have missed one pill, anywhere in the pack:
take the last pill you missed now, even if it means taking two pills in one day
continue taking the rest of the pack as usual
you don't need to use additional contraception, such as condoms
take your seven-day pill-free break as normal
If you have missed two or more pills (you are taking your pill more than 48 hours late), anywhere in the pack:
take the last pill you missed now, even if it means taking two pills in one day
leave any earlier missed pills
continue taking the rest of the pack as usual and use an extra method of contraception for the next seven days
you may need emergency contraception - see below
you may need to start the next pack of pills without a break - see below
Emergency contraception
You may need emergency contraception if you have had unprotected sex in the previous seven days and have missed two or more pills (you are taking your pill more than 48 hours late) in the first week of a pack.
Get advice from your contraception clinic, doctor or pharmacist about this. You can also call NHS Direct on 0845 46 47 (24 hours a day) or the FPA helpline on 0845 122 8690.
Starting the next pack after missing two or more pills
If there are seven or more pills left in the pack after the last missed pill:
finish the pack
have the usual seven-day break
If there are fewer than seven pills left in the pack after the last missed pill:
finish the pack and start the new one the next day, without having a break
There are some risks associated with using the combined contraceptive pill (the pill). However, these risks are small.
For most women, the benefits of the pill outweigh the risks.
Blood clots
The oestrogen in the pill may cause your blood to clot more readily. If a blood clot develops, it could cause a deep vein thrombosis (a blood clot in your leg), pulmonary embolus (a blood clot in your lung), stroke or heart attack.
The risk of getting a blood clot is very small, but your doctor will check if you have certain risk factors that make you more vulnerable before prescribing the pill. The pill can be taken with caution if you have one of the risk factors below, but should not be taken if you have two or more risk factors.
Risk factors include:
being over 35 years old
being a smoker or having quit smoking in the last year
being very overweight (the pill should not be taken if your BMI is over 40)
having migraines (you should not take the pill if you have severe or regular migraine attacks, especially if you get aura or a warning sign before an attack)
having high blood pressure
having had a blood clot or stroke in the past
having a close relative who had a blood clot when they were younger than 45
being immobile for a long time, for example in a wheelchair or with a leg in plaster
Cancer
Research is ongoing into the link between breast cancer and the pill.
Research suggests that users of all types of hormonal contraception have a slightly higher chance of being diagnosed with breast cancer compared with women who do not use them. However, 10 years after you stop taking the pill, your risk of breast cancer goes back to normal.
Research has also suggested a link between the pill and the risk of developing cervical cancer and a rare form of liver cancer.
However, the pill does offer some protection against developing cancers of the endometrium (lining of the womb), ovaries and colon.
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