COVID-19 Information - To see our up to date advice for using our pharmacies - Click Here

Health Knowledge and Encyclopedia

At your local Pearn's Pharmacy we can offer advice on most general health matters. You can also use our Health Encyclopaedia to provide you with the tools and links you need to pinpoint symptoms and get a full explanation of a suspected condition.

Search By Letter
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y |

Search by Keyword

Emergency contraceptive pill


The emergency contraceptive pill, also known as the morning-after pill or post-coital pill, can be used by a woman to prevent pregnancy after having unprotected sex.

It can also be used if another method of contraception has failed, for example if a condom splits or you have forgotten to take one of your contraceptive pills.

The emergency contraceptive pill can be used up to five days (120 hours) after having unprotected sex. However, the sooner it is taken, the more likely it is to prevent pregnancy.

It can be taken more than once during your menstrual cycle, but does not protect you against pregnancy during the rest of your menstrual cycle and is not intended to be a regular form of contraception. Using the emergency contraceptive pill repeatedly can severely disrupt your natural menstrual cycle.

The emergency contraceptive pill does not protect against sexually transmitted infections.

How effective is it?

The effectiveness of the emergency contraceptive pill depends on how soon you take it after sex. Taking it within 12 hours of having sex gives the best chance of preventing a pregnancy.

The emergency contraceptive pill is:

  • 95% effective if taken within 24 hours of having sex
  • 85% effective if taken within 24-48 hours of having sex
  • 58% effective if taken within 48-72 hours of having sex

How the emergency contraceptive pill works

The emergency contraceptive pill prevents the ovaries releasing an egg (ovulation). It also:

  • thickens the mucus in the neck of the womb, so it is harder for sperm to penetrate into the womb and reach an egg
  • thins the lining of the womb, so there is less chance of a fertilised egg implanting into the womb and being able to grow

Types of emergency contraceptive pill

There are currently two brands of emergency contraceptive pill available in the UK:

  • Levonelle is the most commonly used emergency contraceptive pill. It can be taken up to three days (72 hours) after unprotected sex and is available free of charge on prescription or can be bought from your local pharmacy if you are over 16 years of age.
  • ellaOne is a newer type of emergency contraceptive pill that can be taken up to five days (120 hours) after having unprotected sex. It is only available on prescription and only recommended in women over the age of 18.

Other emergency contraception

The copper intrauterine device (IUD) is another method of emergency contraception. This prevents pregnancy if it is fitted within five days of having unprotected sex. For more information, see the topic on the intrauterine device.

Where you can get the emergency contraceptive pill

The emergency contraceptive pill is available free of charge from:

  • your GP
  • most family planning and contraception clinics
  • most sexual health clinics (sometimes referred to as genitourinary medicine or GUM clinics)
  • most young persons' or Brook clinics
  • most NHS walk-in centres(England only) 
  • most NHS minor injury units (MIUs)
  • some hospital accident and emergency (A&E) departments

If you are over 16 years old you can buy the emergency contraceptive pill from most pharmacies and some private health clinics. Prices vary, but it usually costs around £25.

^^ Back to top


Most women can use the emergency contraceptive pill. This includes women who are breastfeeding and women who cannot usually use hormonal contraception, such as the combined pill and contraceptive patch.

However, the emergency contraceptive pill may interact with some medicines (see below).

Breastfeeding women

The emergency contraceptive pill can be taken when breastfeeding. Although small amounts of the hormones contained in the pill may pass into your breast milk, it is not thought to be harmful to your baby.


There is no evidence that the emergency contraceptive pill harms a developing baby. If you are pregnant when you take the emergency contraceptive pill, or you become pregnant after taking it, you might have a slightly increased risk of developing an ectopic pregnancy. You can discuss this further with your GP.

When to avoid it

The emergency contraceptive pill can interact with medicines used to treat epilepsy, HIV and tuberculosis, and with the complementary medicine St John’s Wort. These types of drugs are called enzyme inducers.

The dose of Levonelle or ellaOne may need to be increased if you are using this medication, or you may be advised to use the emergency intrauterine device (IUD) instead.

It is always best to check with your doctor whether any of your medication may interact and change the effectiveness of the emergency pill.

What if I am sick after taking the emergency contraceptive pill?

You may vomit after taking the emergency contraceptive pill. Vomiting within three hours of taking the emergency contraceptive pill may mean that it has not been fully absorbed into your bloodstream. If this happens, there is a chance it will not work properly.

If you vomit within three hours of taking the emergency contraceptive pill, seek medical advice as soon as possible from your GP or a sexual health nurse or pharmacist. You may be advised to take a second emergency contraceptive pill or have an emergency intrauterine device (IUD) fitted.

Can I get the emergency contraceptive pill in advance?

You can get the emergency contraceptive pill in advance of having unprotected sex if:

  • you are worried about your contraceptive method failing
  • you are going on holiday
  • you cannot get hold of emergency contraception easily

Ask your GP or nurse for further information on getting advance emergency contraception.

^^ Back to top

Side effects

Taking the emergency contraceptive pill has not been shown to cause any serious or long-term health problems. However, it can sometimes have side effects.

Common side effects include:

  • abdominal (tummy) pain
  • irregular menstrual bleeding (spotting or heavy bleeding) before your next period is due
  • nausea (feeling sick)
  • tiredness

Less common side effects include:

  • breast tenderness
  • dizziness
  • headache
  • vomiting (being sick) - seek medical advice if you vomit within three hours of taking the emergency contraceptive pill

Any side effects will normally pass quickly.

When to see a doctor or nurse

If you are concerned about any symptoms after taking the emergency contraceptive pill, contact your GP or speak to a nurse at a sexual health clinic. Alternatively, you can call NHS Direct Wales for advice on 0845 4647.

You may also want to talk to a doctor or nurse if:

  • you think you might be pregnant
  • your next period is more than seven days late
  • your period is shorter or lighter than usual
  • you have any sudden or unusual pain in your lower abdomen (tummy)

How it affects your period

After taking the emergency contraceptive pill, most women will have a normal period at the expected time. However, you may have your period later or earlier than normal.

If your period is more than seven days late, or is unusually light or short, contact your GP as soon as possible to check for pregnancy.

Reporting side effects

The Yellow Card Scheme allows you to report suspected side effects from any type of medicine that you are taking. It is run by a medicines safety watchdog called the Medicines and Healthcare products Regulatory Agency (MHRA). See the Yellow Card Scheme website for more information.

^^ Back to top


Other contraception

It is fine to take the emergency contraceptive pill if you are already taking a combined oral contraceptive pill or progestogen-only pill.

If you needed to take the emergency contraceptive pill because you forgot to take some of your regular contraceptive pills or did not use your patch or vaginal ring correctly, you should take your next contraceptive pill, insert a new ring or apply a new patch within 12 hours of taking the emergency contraceptive pill.

You should then continue taking your regular contraceptive pill as normal.

You will need to use additional contraception, such as condoms, for:

  • the next seven days if you use the patch, ring or combined pill
  • the next two days if you use the progestogen-only pill

Other medicines

The emergency contraceptive pill may interact with some other medicines. This includes some immunosuppressant drugs (medicine that weakens the immune systrem), such as ciclosporin, and medicines used to treat liver disease.

There should be no interaction between the emergency contraceptive pill and most antibiotics.

If you want to check that your medicines are safe to take with the emergency contraceptive pill, ask your GP or a pharmacist. You should also read the patient information leaflet that comes with your medicines. 

^^ Back to top


Ectopic pregnancy

The emergency contraceptive pill prevents a fertilised egg from implanting in your womb. However, if you become pregnant despite taking the emergency contraceptive pill, there is a slightly higher risk of it being an ectopic pregnancy. An ectopic pregnancy occurs when the fertilised egg implants outside of the womb, usually in the fallopian tube.

If you become pregnant after taking the emergency contraceptive pill, it is important that you see your GP to rule out the possibility of an ectopic pregnancy. This is particularly important if you have previously had:

  • an ectopic pregnancy
  • fallopian tube surgery
  • pelvic inflammatory disease

You should always see your GP if you develop severe abdominal (tummy) pain. See the topic on ectopic pregnancy for more information.

Does emergency contraception cause an abortion?

Medical research and the law clearly state that emergency contraception prevents pregnancy and is not an abortion. Emergency contraception either stops ovulation, stops the fertilisation of an egg or stops a fertilised egg from implanting in the womb.

Abortion can only take place after a fertilised egg is implanted in the womb.

^^ Back to top


Will antibiotics stop my contraception working?

It depends on which type of contraception you’re using. 

It’s now thought the only types of antibiotic that interact with hormonal contraception and make it less effective are rifampicin and rifabutin.


When you take two or more medicines at the same time, the effects of one medicine can be altered by the other. This is known as an interaction. Some antibiotics can interact with some forms of hormonal contraception. 

Hormonal contraception

There are several types of hormonal contraception, such as: 

  • combined contraceptive pill 
  • progestogen-only contraceptive pill 
  • contraceptive implants and injections 
  • intrauterine system (IUS) 
  • contraceptive patch 
  • vaginal ring 
  • emergency contraception 

If you’re using hormonal contraception, it’s important to understand that some medicines can reduce its effectiveness. This includes some types of antibiotic. If this happens, to avoid getting pregnant you’ll need to use additional contraception, such as condoms, change to a different method of contraception, or take your contraception in a different way. See below for more details.

If you’re not sure if your contraception is affected by other medicines, speak to your GP or pharmacist or call NHS Direct Wales on 0845 4647.


Rifampicin-like medicines are the only types of antibiotic that can make hormonal contraception less effective. This includes:

  • rifampicin
  • rifabutin

These types of medicine can increase the enzymes in your body. This is known as enzyme-inducing and can affect hormonal contraception.

Enzymes are proteins that control your body’s chemical reactions. Enzyme-inducing antibiotics speed up the processing of some contraceptive hormones and therefore reduce the levels of these hormones in your bloodstream. This makes the contraceptive less effective.

Apart from those mentioned above, all other antibiotics are not enzyme-inducing.

Additional contraception

If you’re going to take rifampicin or rifabutin for over two months, you may want to consider starting or changing to a contraception method that’s not affected by these medicines if you’re currently using the: 

  • combined pill 
  • progestogen-only pill
  • implant
  • patch 
  • vaginal ring

Contraception methods that aren’t affected by rifampicin or rifabutin include:

  • progestogen injection
  • intrauterine device (IUD) 
  • IUS

If you’re taking rifampicin or rifabutin for less than two months and want to continue your same hormonal contraception, you must discuss this with your doctor. You may be asked to take this contraception in a different way from usual and use condoms as well. You will need to continue this for 28 days after finishing the antibiotics.

If you’re taking antibiotics other than rifampicin or rifabutin, you don’t normally need to use additional contraception.

However, if the antibiotics, or the illness they are treating, cause diarrhoea or vomiting, your oral hormonal contraception may be affected. For more information, see below.

What if I’m on the pill and I’m sick or have diarrhoea?

It depends on how long you’re being sick or have diarrhoea for.

If you are sick (vomit) within two hours of taking your contraceptive pill, it will not have been absorbed by your body. You should take another pill straight away. As long as you’re not sick again, you’re still protected against pregnancy. Take your next pill at the usual time. 

If you continue to be sick or have severe diarrhoea (passing six to eight watery stools in 24 hours), this can mean that your protection against pregnancy is affected.

Sickness or severe diarrhoea for more than 24 hours

If you continue to be sick for more than 24 hours, or you have severe diarrhoea for more than 24 hours, count each day with sickness or diarrhoea as a day that you’ve missed your pill (see below).

If you can, you should carry on taking your pills at the normal time, but you may need to use extra contraception. 

Missed pills

Missing pills or starting a new pack late can make your pill less effective at preventing pregnancy. You may need to use extra contraception such as condoms. You may also need emergency contraception. The advice depends on:

  • which type of contraceptive pill you take
  • when you missed the pills (where in the packet you are)
  • how many pills you’ve missed

For advice on what to do if you’ve missed a pill, see:

If you’re on the combined pill Qlaira and you’ve missed a pill, see the manufacturer’s Qlaira patient information leaflet on the electronic Medicines Compendium website or get advice.

^^ Back to top
“Pearn's Pharmacies, putting patients first”

Pearn's Pharmacy Services

Common Ailment Service

Primary Choice is a campaign to help the public choose the right health advice in the community.

Tell Me More


Repeat, one-off prescriptions. Collect in store or home delivery.

Sign Up

Funded Services

Browse our NHS funded services offered in our stores.

See Services


We are receiving an increase in the number of requests for delivery of medicines due to the COVID-19 pandemic.

Important Info

Find a GP   

Use our GP locator service and nearest Pearn's Pharmacy Branch

Search Now