Learn more about possible side effects, male contraceptive pills & how the pill can affect your hormones 


Contraceptive pills are small tablets that you take every day (or for 21 days at a time, depending on the type of pill) to stop you from becoming pregnant. 


Deciding to take the pill as a form of contraception is a big decision, and there is a lot of information you should arm yourself with beforehand. From the difference between the combined and ‘mini’ pill to whether there is a ‘best’ contraceptive pill, we answer the most googled questions about the contraceptive pill. 


How does the contraceptive pill work? 


When taken correctly, the hormones in the combined pill stop pregnancy occurring by preventing your body from releasing an egg (ovulating) each month, as well as making it harder for an egg to get fertilised by sperm and attach to the wall of the uterus. 


The progestogen-only pill (or ‘mini pill’) thickens the cervical mucus and thins the lining of the uterus, which prevents sperm from being able to reach an egg. 


The pill does not protect against sexually transmitted infections (STIs). To protect against STIs, it’s recommended to use a condom as well. 


What’s the difference between the combined pill and the ‘mini’ pill


The combined pill contains artificial versions of female hormones oestrogen and progestogen. These hormones work to prevent your body from releasing an egg (ovulating) each month, as well as making it harder for an egg to be fertilised by sperm and attach to the wall of the uterus. 


You’ll usually need to take one pill at around the same time every day for 21 days, then you take a break for seven days before taking the pill again. Always make sure you follow the instructions that come with your pack. 


The progestogen-only pill only contains the progestogen hormone. There are two different types, the traditional progestogen-only pill (which must be taken within three hours of the same time each day) and the desogestrel progestogen-only pill (which must be taken within 12 hours of the same time each day). The traditional progestogen-only pill prevents pregnancy by thickening the mucus in the cervix to stop sperm reaching an egg; the desogestrel progestogen-only pill can also stop ovulation. Always follow the instructions that come with your pill packet. 


The pill isn’t suitable for everyone, and to find out what is right for you, talk to your GP, nurse or pharmacist. 


What is the effectiveness of the pill? 


When taken correctly (at the same time each day for the progestogen-only pill and around the same time each day for the combined pill), both pill types are over 99% effective at preventing pregnancy. This means that fewer than one in 100 people taking the contraceptive pill will get pregnant in a year.


Can you get pregnant on the pill? 


It is possible to get pregnant while taking the pill under certain circumstances. These include: 


• If you do not take the pill at around the same time every day (or the same time each day for the progestogen-only pill)

• If you miss a pill 

• If you vomit after taking a pill 

• If you have severe diarrhoea 

• If you are taking certain medicines or supplements 


Birth control pills are designed to maintain a constant level of hormone(s) in your body and missing a pill can cause your hormone levels to drop quickly. Depending on where you are in your cycle and if you are taking the combined pill or desogestrel progestogen-only pill, missing a pill may also cause you to ovulate (release an egg), which can increase your chance of getting pregnant if you have unprotected sex. 


Does the pill stop your periods? 

Combined pill 


If you are taking the combined contraceptive pill in the standard way (for 21 days followed by a seven-day break), you will still experience a monthly bleed (normally referred to as a withdrawal bleed rather than a period). 


Because the combined pill works to alter your hormone levels, it’s possible to delay your period. 


With monophasic 21-day combined pills, you take a pill for 21 days, followed by seven days without pills, when you have a bleed (period). To delay your period, you can start a new packet of pills straight after you finish the last pill and miss out the seven-day break.


With every day (ED) combined pills, you take a pill every day. The first 21 pills are active pills and the next seven pills are inactive or dummy pills, when you have your bleed (period). To delay your period, miss out and throw away the dummy pills, and start the active pills in a new packet straight away. If you’re not sure which are the dummy pills in the pack, speak to your GP or pharmacist. 


If the type of combined pill you take is a phasic 21-day pill (which has two or three sections of different coloured pills in a pack), the pills need to be taken in the correct order, so you should talk to your GP or pharmacist for advice before taking this type of pill without a break. 


If you take the pill without a break, the pill will continue to remain effective and you won’t need to use another method of contraception to prevent pregnancy. You should avoid taking more than two packs of pills without a break, unless your GP says that you can. Skipping a period may cause side effects such as feeling sick or vomiting, diarrhoea and unexpected vaginal bleeding. 


Progestogen-only pill 


If you are taking the progestogen-only (‘mini’) pill, your periods may stop or become lighter, irregular or more frequent.


Once you stop taking the pill, your menstrual cycle and your periods will return as normal. Neither pill type will stop your periods permanently.


What are the side effects? 


Minor side effects of the pill can include: 


• Mood swings

• Nausea 

• Breast tenderness 

• Headaches 


Any side effects will usually settle down within a few months. If they don’t go after a few months, it may help to change to a different pill. Some people may not experience any side effects. 


There is no evidence that the pill will make you gain weight.


Are there any serious or long-term side effects?


There's a very low risk of serious side effects or risks with the contraceptive pill. However, the main risks associated with the pill include: 


• An increase in your blood pressure 

• An increase in your risk of blood clots 

• An increase in your risk of breast cancer and cervical cancer


These risks are considered very small for most women. If you have concerns about any of these risks, it’s important that you discuss them with your GP. 


Can it prevent acne? 


The combined pill can be used as a treatment for moderate to severe hormonal acne. Acne occurs when there is a build-up of sebum produced by your hair follicles, normally due to the follicles become blocked with oil and dead skin cells. But this build-up of sebum can also be caused by changing hormonal levels.  


A combined contraceptive pill is prescribed as it can help balance hormone levels, avoiding flare-ups caused by hormonal changes. If you would like to take a combined pill to help with acne, consult your GP. 


Can it help with PCOS? 


Polycystic ovary syndrome (PCOS) is a common condition that affects a person’s periods, fertility, hormones and your physical appearance. Some people with PCOS may be prescribed the contraceptive pill to help regulate their hormonal imbalance and menstrual cycle.


How do I get the pill? 


The contraceptive pill is free to all women of child-bearing age through the NHS. You can access it through: 


• Your GP surgery – talk to your GP or a nurse 

• Community contraception clinics 

• Sexual health clinics 

• Some genitourinary medicine (GUM) clinics 

• Some young people's services (call the Sexual Health Line on 0300 123 7123 for more information)


If you’d like to begin taking the contraceptive pill, visit your GP or a practice nurse who can assess whether it is suitable for you to take and can help find the best pill for you. 


You can also access the contraceptive pill through the Boots Online Doctor Contraceptive Pill Service*. Simply complete an online consultation and a clinician will review your answers within 24 hours and prescribe a contraceptive pill if suitable for you. 


There are also progestogen-only pills (Hana and Lovima) that are available to purchase from a pharmacy (without the need for a prescription). You can buy one or three-month packs in Boots stores or online. The pharmacist will check whether the pill is suitable for you before it is supplied.


What’s the best contraceptive pill?


There are many different brands of contraceptive pill available, and one that is considered most suitable for you may not be the same for another person. Visit your GP for a consultation to discuss the best option for you. It’s a good idea to seek advice from your GP or pharmacist before changing brand too.  


All types of contraceptive pill are equally effective at preventing pregnancy when taking correctly. 


How do I take the pill for the first time? 


You can normally start taking the combined pill at any point in your menstrual cycle. However, you may need to use additional contraception, such as condoms, when you begin taking it, depending on where you are in your cycle. 


If you begin taking the combined pill on the fifth day of your cycle (with the first day being the first day of your period) or before, you’ll be protected from pregnancy straight away and won’t need additional contraception. If you begin taking the combined pill after the fifth 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. 


You can start the progestogen-only pill at any time in your menstrual cycle, too. If you begin taking it on the fifth day of your cycle or before, you’ll be protected from pregnancy straight away and won’t need additional contraception. If you have a short menstrual cycle, you should use additional contraception until you’ve taken the pill for two days. If you begin taking it on any other day of your cycle, you will also need to use additional contraception until you’ve taken the pill for two days. 


There is special guidance if you have just had a baby, abortion, or miscarriage. You should always seek advice from a doctor, nurse or pharmacist when beginning to take the contraceptive pill. 


What do I do if I miss a pill? 


If you're on the pill and you miss taking one, what you need to do depends on:  


• How many pills you have missed 

• When you missed your pill (where you are in the pack)

• The type of combined pill you're taking


If you have missed a combined pill anywhere in the pack or started a new pack one day late, you'll still be protected against pregnancy and you won’t need to use extra contraception. You should:


• Take the last pill you missed now, even if this means taking two pills in one day

• Take the rest of the pack as normal

• Take your seven-day pill-free break as normal


If you have missed two or more pills anywhere in the pack or started a new pack late (48 hours or more), your protection against pregnancy may be affected. 


If you forget to take a progestogen-only pill, you should also take into account:


• Whether you've had sex without using another type of contraception in the previous seven days

• If you're less than three hours or less than 12 hours late taking the pill, depending on the type of progestogen-only pill you are taking


If you're taking a three-hour progestogen-only pill and are less than three hours late taking it, or if you're taking the 12-hour progestogen-only pill and are less than 12 hours late taking it:


• Take the late pill as soon as you remember, and

• Take the remaining pills as normal, even if that means taking two pills on the same day


If you're taking a three-hour progestogen-only pill and are more than three hours late taking in, or you’re taking a 12-hour progestogen-only pill and more than 12 hours late taking it, you will not be protected against pregnancy. You should: 


• Take the late pill as soon as you remember, and

• Take the remaining pills as normal, even if that means taking two pills on the same day

• Use extra contraception for the next two days after you remember to take your missed pill, or do not have sex 


Find out more about what to do if you miss your pill


When will the male contraceptive pill be available? 


There are many ongoing research projects into methods of male contraception. Researchers are optimistic that a safe and effective male contraception pill will become a reality, although this is still several years away.


If you currently take, or would like to begin taking the contraceptive pill and have any questions or would like some more information into how the contraceptive pill works to prevent pregnancy, you can always seek advice from a GP, practice nurse or pharmacist. 

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*Subject to availability. Charges apply. Treatments provided by Boots Online Doctor are subject to an online consultation with a clinician to check suitability.