Contraception: Combined Oral Contraceptive Pill (COCP)

The pill stops the ovaries from releasing an egg each month (ovulation).

It also:

• thickens the mucus in the cervix (neck of the womb); this makes it harder for sperm to move through it and reach an egg
• makes the lining of the uterus (womb) thinner so it is less likely for a fertilised egg to be able to implant into the womb and create a pregnancy.

If the combined pill is always used perfectly, according to instructions, it’s over 99% effective.

This means that less than one in 100 women who use the combined pill will get pregnant in one year.

If the combined pill is not always used according to instructions, about nine in 100 pill users will get pregnant in one year.

If you are healthy, a non-smoker, and there are no medical reasons for you not to take the combined oral contraceptive pill (COCP), you can use it until you’re 50 years old. However not everyone can use the COCP.

The combined pill might not be suitable if:

• you smoke and are 35 years old or over
• you’re 35 years old or over and stopped smoking less than a year ago
• you’re very overweight
• you take certain medicines
• you’re breastfeeding a baby less than six weeks old

The combined pill might not be suitable for you if you have now or had in the past:

• Thrombosis (blood clots) in any vein or artery or a member of your immediate family had thrombosis when they were younger than 46 years old
• heart disease or a stroke
• systemic lupus erythematosus with positive antiphospholipid antibodies
• hypertension (raised blood pressure)
• migraine with aura
• Breast cancer or you have the gene that’s associated with breast cancer
• liver or gall bladder disease
• Diabetes with complications
• you are immobile for a long period of time or use a wheelchair
• you are at high altitude (more than 4,500m) for more than a week.

Some of the advantages of the pill are:

• it usually makes your bleeds regular, lighter and less painful
• it gives you the choice not to have a monthly bleed
• it may reduce symptoms of PMS (premenstrual syndrome)
• it can sometimes improve acne
• it may reduce symptoms of endometriosis
• it may help with symptoms associated with polycystic ovarian syndrome (PCOS).
• it reduces the risk of cancer of the ovary, uterus, and colon.

There are some serious possible side effects (see risks).

In addition: 

• you may get temporary side effects at first including headaches, nausea, breast tenderness and mood changes; if these don’t stop within a few months, changing the type of pill may help
• the pill may increase your blood pressure
• the pill doesn’t protect you from sexually transmitted infections, so you may want to use condoms as well
• breakthrough bleeding (unexpected vaginal bleeding on pill taking days) and spotting is common in the first few months of using the pill.

There are some risks associated with using the combined oral contraceptive pill. These include:

Blood clots

The combined oral contraceptive pill increases the risk of:

• Deep vein thrombosis (blood clot in the leg)
• Pulmonary embolus (blood clot in the lung)
• Stroke
• Heart attack

These risks are very small. Your doctor or nurse will ask you questions to check whether you could be at higher risk of these conditions before deciding if it is suitable to prescribe you the pill.

Cancer

Research suggests that combined oral contraceptive pill users appear to have a small increased risk of being diagnosed with breast cancer compared to non-users of hormonal contraception. This risk reduces with time after stopping the pill and is undetectable 10 years after stopping.

Research suggests there’s a small increase in the risk of developing cervical cancer with longer use of the combined pill. This reduces over time after stopping the pill.

You must see a doctor straight away if you have any of the following:

• pain in the chest, including any sharp pain which is worse when you breathe in, breathlessness, or coughing up blood
• painful swelling in your leg(s)
• weakness, numbness, or bad ‘pins and needles’ in an arm or leg
• unusual headaches or migraines that are worse than usual
• sudden problems with your speech or eyesight

If you develop any new conditions, tell your doctor or nurse so they can check it’s still safe for you to take the pill.

If you go into hospital for an operation or have an accident which affects the movement of your legs, tell the doctor you’re taking the combined pill. You may need to stop taking the pill or need other treatment to reduce the risk of developing thrombosis. There are other contraceptive methods you can use instead.

You can normally start taking the combined oral contraceptive pill at any point in your menstrual cycle.

There is special guidance if you have just had a baby, abortion or miscarriage.

You can start the pill any time in your menstrual cycle if you’re sure you’re not pregnant.

If you start the pill:

• On the first day of your period, you’ll be protected from pregnancy immediately.
• Up to, and including, the fifth day of your period, you’ll be protected from pregnancy immediately.
• At any other time in your menstrual cycle, you’ll need to avoid sex or use additional contraception, such as condoms, for the first seven days of pill-taking.

If you have a short menstrual cycle with your period coming every 23 days or less, starting the COCP as late as the fifth day of your period may not give you immediate contraceptive protection. This is because you may ovulate (release an egg) early in your menstrual cycle. You may wish to talk to your doctor or nurse about this and whether you need additional contraception for the first seven days.

If you start the pill after having had unprotected sex or after taking emergency contraception please do a pregnancy test three weeks after the last time you had unprotected sex.

There are different types of pills and many different brands which are taken differently.

The combined pill is designed to give you a withdrawal bleed once a month. A withdrawal bleed isn’t the same as your period. It’s caused by you not taking hormones during a pill-free break or on placebo pill days.

Most instructions tell you to take a seven-day pill-free break but you can choose to shorten this break, or to miss it and not have a withdrawal bleed.

Missing or shortening the break could help you if you get heavy or painful bleeding, headaches, or mood swings on pill-free days.

When you miss taking a pill just before or just after a pill-free break, you’re more at risk of pregnancy. Taking a shorter break or missing the break might make it less risky that you’ll get pregnant if you forget to take a pill at another time.

Brands of pills

There are many different brands of pill made up of three main types:

1. Monophasic 21 day pills

This is the most common type of pill. There are 21 pills in a pack and each pill has the same amount of hormone. You can take the monophasic pill in the following ways.

• One pill a day for 21 days then no pills for the next four or seven days (21/4 or 21/7). This is the standard way to take the pill. You’ll usually have a withdrawal bleed during the pill-free break. Start taking the pill again on the fifth or eighth day even if you’re still bleeding.
• One pill a day for nine weeks (three packs of pills) then no pills for the next four or seven days (63/4 or 63/7). This is called extended use or tricycling. You’ll usually have a withdrawal bleed during the pill-free break. Start taking the pill again on the fifth or eighth day even if you’re still bleeding.
• One pill a day every day with no break. This is called continuous pill-taking. You won’t have a withdrawal bleed but you may still get some breakthrough bleeding (unexpected vaginal bleeding on pill taking days), which may be occasional or more frequent. Any bleeding you get is likely to reduce over time if you keep taking the pill continuously.
• One pill a day every day for at least 21 days. If you get breakthrough bleeding (unexpected vaginal bleeding on pill taking days)  that’s unacceptable to you for three-four days, then stop taking your pills for four days. This is called flexible extended use. Start taking the pill again on the fifth day, even if you’re still bleeding. This can help manage the bleeding. Restart with the pill marked with the correct day of the week and take at least 21 pills before taking your next break.

2. Every day (ED) monophasic pills

There are 21 active pills and seven inactive (dummy or sugar) 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. Microgynon ED is an example of this type of pill.

3. Phasic 21 day pills

These pills contain different amounts of hormone so you must take them in the right order. There are two or three sections of different coloured pills in the pack. You take one pill a day for 21 days then no pills for the next seven days.

Take the first pill from the section of the pack marked ‘start’. This will be an active pill. Take a pill every day until the pack is finished (21 days). Take the pills in the correct order and try to take them at the same time each day. Taking the pills in the wrong order could mean you’re not protected from pregnancy.

You then stop taking pills for seven days (or take seven inactive pills if you’re taking an EveryDay Phasic pill). You’ll usually have a withdrawal bleed. Start your next pack on the eighth day even if you’re still bleeding.

It’s very important to take your pill as instructed. When taking your first pill, choose a convenient time. This can be any time of day. Taking a pill at the same time each day will help you remember to take it regularly.

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

What should I do if I miss a pill (combined pill)? - NHS UK

Vomiting and diarrhoea

If you vomit within three hours of taking a pill, it won’t have been absorbed by your body, so it’s as if you hadn’t taken it. 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 until you’ve taken the pill for seven days without vomiting.

If you have very severe diarrhoea that continues for more than 24 hours, this may make the pill less effective. Keep taking your pill at the normal time, but treat each day that you have severe diarrhoea as if you’d missed a pill. Keep using another form of contraception until you’ve taken the pill for seven days without diarrhoea.

Speak to a doctor or nurse or call NHS 111 for more information if your sickness or diarrhoea continues.

Some medicines may make the COCP less effective. These include some of the medicines used to treat HIV, epilepsy and tuberculosis (TB), and the complementary medicine St John’s Wort. These are called enzyme-inducing drugs. If you take these medicines, it’ll be recommended that you change to a different method of contraception or that you use additional contraception, such as condoms.

Always tell your healthcare professional that you’re taking the COCP if you’re prescribed any medicines.