The combined oral contraceptive pill is usually known as the pill. It contains synthetic female hormones, oestrogen and progestogen. The hormones in the pill mimic the ones made naturally in the ovaries.
The hormones in the pill stop a woman's ovaries from releasing an egg (ovulating). They also make it difficult for sperm to reach an egg, or for an egg to implant itself in the lining of the womb.
The pill is usually taken to prevent pregnancy, but can also be used to treat:
- painful periods
- heavy periods
- premenstrual syndrome (PMS)
At a glance: the combined pill
When taken correctly, the pill is over 99% effective at preventing pregnancy. This means that fewer than 1 woman in 100 who use the combined pill as contraception will get pregnant in a year.
In real world use, about 8 in 100 women who use the combined pill a year become pregnant due to incorrect use such as forgetting to take pills (92% effective).
You need to take the pill every day for 21 days, then stop for 7 days, and during this week you have a period-type bleed. You'll still be protected against pregnancy during these 7 days. You start taking the pill again after 7 days.
You need to take the pill at the same time every day. If you don't, you could get pregnant. You can also get pregnant if you miss a pill, or vomit or have severe diarrhoea.
Minor side effects include mood swings, breast tenderness and headaches.
There is no evidence that the pill makes women gain weight.
There's a very low risk of serious side effects, such as blood clots and cervical cancer.
The combined pill is not suitable for women over 35 who smoke, or women with certain medical conditions.
The pill does not protect against sexually transmitted infections (STIs). Using a condom as well will help to protect you against STIs.
How the combined pill works
The pill prevents the ovaries from releasing an egg each month (ovulation). It also:
- thickens the mucus in the neck of the womb, so it's harder for sperm to reach an egg
- thins the lining of the womb, so there's less chance of a fertilised egg implanting into the womb and being able to grow
Although there are many different brands of pill, there are 3 main types.
Monophasic 21-day pills
This is 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 7 days. Microgynon, Rigevidon and Brevinor are examples of this type of pill.
Phasic 21-day pills
Phasic pills contain 2 or 3 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 7 days. Phasic pills need to be taken in the right order. Synphase and Logynon are examples of this type of pill.
Every day (ED) pills
There are 21 active pills and 7 inactive (dummy) pills in a pack. The 2 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. Microgynon ED and Logynon ED are examples of this type of pill.
Follow the instructions that come with your packet. If you have any questions about how to take the pill, ask your GP, nurse or pharmacist. It's important to take the pills as instructed. Missing pills or taking them at the same time as certain medicines may make them less effective.
How to take 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 7 days (during these 7 days you'll 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.
How to take 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 7 days of taking the inactive pills, you'll get a bleed (like a period).
- Start your next pack of pills after you have finished the first, whether you are still bleeding or not.
Starting the combined pill
Most women can start the pill at any time in their menstrual cycle. There is special guidance if you have just had a baby, abortion or 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.
If you start the combined pill on the first day of your period (day 1 of your menstrual cycle) you'll be protected from pregnancy straight away. You will not need any additional contraception.
If you start the pill on the fifth day of your period or before, you'll 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'll need additional contraception, such as condoms, until you have taken the pill for 7 days.
If you start the pill on any other day of your cycle, you will not be protected from pregnancy straight away. You'll need additional contraception until you have taken the pill for 7 days.
Taking pill packs back-to-back (continuously)
For monophasic pills, you can run packs together.
What happens when I take the pill in the usual way?
When you take the combined pill it prevents ovulation (the release of an egg from your ovaries). There are also some changes in the lining of your womb in the 3 weeks that you take the pill. When you stop your pill for your 7 day break, the withdrawal of hormones allows the womb lining to break down so you have a period-like bleed. If you don’t have the 7 day break, the lining of the womb remains unchanged (blood does not build up).
If you do not want to have a bleed every month, you can safely continue your pill taking and have fewer bleeds. If you do this correctly, the pill remains as effective.
Can I run 2 strips together?
This would give you 7 to 8 bleeds each year instead of 13. Take 6 weeks of pills (2 foil strips in a row) then have a 7 day break. During the break you'll usually have a bleed. After your 7 day break, start a new strip on the same day of the week as you started the previous strips.
Can I run 3 strips together?
This would give you 5 bleeds a year. Take 9 weeks of pills (3 foil strips in a row) and then have a 7 day break. During the break you'll usually have a bleed. After your 7 day break start a new strip on the same day of the week as you started the previous strips.
Can I take my pill continuously?
Take your pill continuously until you have bleeding for 3 to 4 days then stop the pill (as long as you've taken the pill for at least 21 days continuously). You only need to be off the pill for 4 days but this does mean restarting your pills on a different day of the week so you may prefer just to have the 7 day break. Do not stop taking your pills for more than 7 days.
I have been taking the pills like this and I have some bleeding. What do I do?
This is not usually harmful, and if you have not missed pills or taken a break longer than 7 days, your pill will still be effective. Continue with your pills as normal. If your unpredictable bleeding persists, contact your GP or sexual health service for advice.
What to do if you miss a pill
If you miss a pill or pills, or you start a pack late, this can make the pill less effective at preventing pregnancy. 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've missed a pill when it's 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. You'll still be protected against pregnancy (known as having contraceptive cover).
However, missing 2 or more pills, or starting the pack 2 or more days late (more than 48 hours late) may affect your contraceptive cover. In particular, if you make the 7-day pill-free break longer by forgetting 2 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 7-day break.
If you miss a pill, follow this advice. 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 1 pill, anywhere in the pack:
- take the last pill you missed now, even if it means taking 2 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 7-day pill-free break as normal
If you have missed 2 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 2 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 7 days
- you may need emergency contraception
- you may need to start the next pack of pills without a break
You may need emergency contraception if you've had unprotected sex in the previous 7 days and have missed 2 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 phone 111.
Starting the next pack after missing 2 or more pills
If there are 7 or more pills left in the pack after the last missed pill:
- finish the pack
- have the usual 7-day break
If there are fewer than 7 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
Vomiting and diarrhoea
If you vomit within 2 hours of taking the combined 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 continue to be sick, keep using another form of contraception while you're ill and for 2 days after recovering.
Very severe diarrhoea (6 to 8 watery stools in 24 hours) may also mean that the pill doesn't 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.
Speak to your GP or contraception nurse or phone 111 for more information, or if your sickness or diarrhoea continues.
Who can use the combined pill?
The combined pill is not suitable for everyone. If you're thinking of using it, your doctor or nurse will need to ask you about your health and your family’s medical history, to make sure it's right for you. It's very important to tell them about any illnesses or operations you've had, or medications you're currently taking.
You should not use the combined pill if you:
- are pregnant or think you may be pregnant
- are breastfeeding
- smoke and are 35 or over
- are 35 or over and stopped smoking less than a year ago
- are very overweight
- take certain medicines, such as some antibiotics, St John’s Wort or medicines used to treat epilepsy, tuberculosis (TB) or HIV
You will also not be able to use the combined pill if you have (or have had):
- thrombosis (blood clots) in a vein or artery
- a heart problem or a disease affecting your blood circulatory system (including high blood pressure)
- migraine with aura (warning signs)
- breast cancer
- disease of the liver or gallbladder
- diabetes with complications, or diabetes for more than 20 years
After having a baby
If you have just had a baby and are not breastfeeding, you can start the pill on day 21 after the birth. You'll be protected against pregnancy straight away. If you start the pill later than 21 days after giving birth, you'll need additional contraception (such as condoms) for the next 7 days.
If you're breastfeeding a baby less than 6 months old, taking the pill can reduce your flow of milk. It's 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, you can start the pill up to 5 days after this and you'll be protected from pregnancy straight away. If you start the pill more than 5 days after the miscarriage or abortion, you'll need to use additional contraception until you have taken the pill for 7 days.
Advantages and disadvantages of the combined pill
Some advantages of the pill are that it:
- doesn't interrupt sex
- usually makes your bleeds regular, lighter and less painful
- reduces your risk of cancer of the ovaries, womb and colon
- can reduce symptoms of PMS
- can sometimes reduce acne
- may protect against pelvic inflammatory disease
- may reduce the risk of fibroids, ovarian cysts and non-cancerous breast disease
Some disadvantages of the pill are:
- 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
- it has been linked to an increased risk of some serious health conditions, such as thrombosis (blood clots) and breast cancer
The combined pill with other medicines
Some medicines interact with the combined pill and it doesn't work properly. Some interactions are listed on this page, but it is not a complete list. If you want to check your medicines are safe to take with the combined pill, you can:
- ask your GP, practice nurse, pharmacist or local sexual health clinic
- read the patient information leaflet that comes with your medicine
The antibiotics rifampicin and rifabutin (which can be used to treat illnesses including tuberculosis and meningitis) can reduce the effectiveness of the combined pill. Other antibiotics do not have this effect.
If you are prescribed rifampicin or rifabutin, you may need additional contraception (such as condoms) while taking the antibiotic. Speak to your doctor or go to the sexual health clinic for advice.
Epilepsy and HIV medicines, and St John's wort
The combined pill can interact with medicines called enzyme inducers. These speed up the breakdown of progestogen by your liver, reducing the effectiveness of the pill.
Examples of enzyme inducers are:
- 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 you to use an alternative or additional form of contraception while taking any of these medicines.
Risks of taking the combined pill
There are some risks associated with using the combined contraceptive pill. However, these risks are small and, for most women, the benefits of the pill outweigh the risks.
The oestrogen in the pill may cause your blood to clot more readily. If a blood clot develops, it could cause deep vein thrombosis (clot in your leg), pulmonary embolus (clot in your lung), stroke or heart attack. The risk of getting a blood clot is very small. 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 you should not take it if you have 2 or more risk factors. These include:
- being 35 years old or over
- being a smoker or having quit smoking in the past year
- being very overweight (in women with a BMI of 35 or over, the risks of using the pill usually outweigh the benefits)
- 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
Research is ongoing into the link between breast cancer and the pill. 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 endometrium (lining of the womb) cancer, ovarian cancer and colon cancer.
Where can you get the combined pill?
Most types of contraception are available for free in the UK. Contraception is free to all women and men through the NHS. Places where you can get contraception include:
- most GP practices – talk to your GP or practice nurse
- sexual health clinics – they also offer contraceptive and STI testing services
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 won't tell your parents (or carer). They'll provide you with contraception as long as they believe you fully understand the information you're given and are able to use the contraception safely.
Doctors and nurses have a responsibility to make sure that you are safe and free from harm. They'll encourage you to consider telling your parents (or carer), but they won't make you. The only time that a professional will not be able to keep confidentiality is if they believe you're at risk of serious harm, such as abuse. If this was the case they would usually discuss it with you first.