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The combined pill: what it is and how it works

Contraception  •  27 March 2023  • 8 min read



There are two types of contraceptive pill: the combined pill, and the progestogen-only pill (sometimes called the mini-pill). The combined pill is a daily tablet that contains two hormones: progestogen and oestrogen. The mini-pill is a daily pill that only contains one hormone: progestogen. In this blog, we give you all you need to know about the combined pill. 

In this blog, you will find information about: 

  • What the combined pill is 
  • How to use the combined pill 
  • The effectiveness of the combined pill 
  • The combined pill and your period 
  • Disadvantages and side effects of the combined pill 
  • The contraceptive pill and blood clots 
  • What to do if you miss a combined pill 
  • Our digital contraception counsellor, ‘Choice’

What is the combined pill?

The combined pill is a daily tablet that contains two hormones, progestogen and oestrogen, which are similar to hormones in your body. 

The hormones prevent an egg from being released by the ovaries each month and make it harder for sperm to get into the uterus (womb). 

The pill needs to be taken once a day for three weeks and then you can have a week’s break to have a period, or you can continue to take the pill every day to avoid having a period. 

How do I use the combined pill?

In your first appointment with a doctor or clinician, you will discuss a range of contraceptive methods to find the one that suits you. Often, you will talk about your lifestyle, preferences, needs and medical history, and the clinician will assess the risks and benefits of contraceptive methods for the individual, considering all alternatives. 

If it is agreed in this first appointment that the combined pill is the right method for you, you will be prescribed a short course of the combined pill. Your prescription will be reviewed after this course, and you can discuss any side effects/issues you might have with a clinician at this point. 

You can start to take the contraceptive pill at any point in your menstrual cycle, but make sure to choose a convenient time to take it. This can be any time of the day, but once you’ve chosen a time you must then take on pill each day at this same time every day. 

If you start the combined pill at any time from the first day of your period to the fifth day of your period, you will be protected from pregnancy straight away, and don’t need to use any additional contraception. If you start taking the pill after the fifth day of your cycle, you will not be protected from pregnancy straight away. In this case, you will need to use additional contraception – such as a condom – until you have been taking the pill for seven days. 

Effectiveness of the combined pill

The pill works very well at preventing pregnancy. However, its ability to prevent a pregnancy largely depends on a person using it properly. 

With perfect use, the combined pill is more than 99% effective. Fewer than 1 in 100 people will get pregnant in a year when using the combined pill correctly. 

With typical use, the combined pill is around 91% effective. Around 9 in 100 people using the combined pill will get pregnant in a year. 

Remember, if you think you will not be able to take a pill at the same time each day, the contraceptive pill may not be the right method for you. 

The combined pill and your period

As with all contraception, there are a number of advantages and disadvantages to taking the combined pill. 

One advantage of using the combined pill is that it can make your periods regular, lighter and less painful. 

The combined pill also gives you more control over your periods: you can choose not to have a period (by continuing to take the pill without a week’s break), or to delay your period. 

Disadvantages of the combined pill

Combined pill side effects 

You may get temporary side effects when you first start taking the combined pill, including headaches, nausea, breast tenderness and mood changes. 

Irregular bleeding and spotting may also occur in the first few months of use. This is normal, and does not mean that the pill is not working properly. 

Other disadvantages include: 

  • The pill has to be taken once per day. Forgetting to take the pill on a daily basis could make it fail. If you do not have a routine and think you may struggle to take the pill at the same time each day, it may not be the right method for you. 
  • The pill may not work if you experience vomiting or diarrhoea. 
  • The use of some medications, such as those for seizures or fits, HIV or for tuberculosis, can make the contraceptive pill less effective. Check with your medical provider if your medications are compatible with use of the pill. 
  • Condoms are the only contraceptive method which protect against sexually transmitted infections. To ensure protection from both pregnancy and infection, we recommend “dual protection”. This means using a male or female condom in addition to the contraceptive method of your choice to prevent pregnancy. 

The contraceptive pill and blood clots

The combined pill is associated with some rare risks. For most people, the benefits of taking the combined pill outweigh the possible risks, but it is essential that our clients have access to quality advice and information when it comes to contraception. 

Some of the rare risks associated with combined contraceptive methods include the development of a blood clot in your leg or lungs, a heart attack, or a stroke. 

Your clinician or contraception provider will ask you questions to check whether you could be at a higher risk, for example, if you smoke, have high blood pressure, are overweight, take certain medicines or have a certain family medical history. 

To read more about the contraceptive pill and blood clot risks, read our interview with Julia Hogan, Independent Trainer in Long-Acting Reversible Contraception. 

What to do if you miss a combined pill

What to do if you miss a pill depends largely on how many pills you have missed, when you missed your pill, and the type of combined pill you’re taking. 

If you have missed one pill or started a new pack one day late, you are still protected against pregnancy. You should take the last pill you missed now (even if this means taking two pills in one day), and carry on taking the rest of the pack as normal. 

If you have missed two or more pills, you may not be protected against pregnancy. You should take the last pill you missed now, leave any earlier missed pills, and carry on taking the rest of the pack as normal. However, it is essential that you use extra contraception, such as a condom, for the next seven days. 

VIDEO: The combined contraceptive pill

In this short video, we share all you need to know about the combined contraceptive pill, including how to use it, how effective it is, advantages, disadvantages and risks. 

“CHOICE”: MSI UK’s digital contraception counsellor

At MSI UK, we believe that information about contraception should be readily available. If you need help finding the best contraceptive method for you, try our digital contraception counsellor “Choice”. Using “Choice”, you can receive personalised contraceptive advice by answering a few short questions about your lifestyle, preferences, needs and medical history.  

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