Emergency contraception is an option that can help reduce the chance of an unwanted pregnancy after unprotected sex, or when the contraceptive method used has for some reason turned out not to be reliable. The morning-after pill that can be used in such situations works by delaying or preventing ovulation, but it is important to know that it does not protect against pregnancy 100% of the time, and its effectiveness depends greatly on how quickly it is taken. As a general rule, it should be taken as soon as possible, because its effectiveness may decrease as time passes.
In this comprehensive guide we explain how emergency contraception works, when it may be needed, which options are available, how effective it is, what side effects it may cause, and when it is advisable to see a doctor. Our aim is to support a responsible decision with reliable, plain and up-to-date information.
The essentials in brief
- Time is the most important factor – the sooner it is taken, the more effective it is, ideally within the first 24 hours.
- Two active substances: levonorgestrel can be used within 72 hours, ulipristal acetate within 120 hours.
- It is not an abortion pill: it delays ovulation and does not end an existing pregnancy.
- Availability differs by country – in most European countries the pills are sold in pharmacies without a prescription, while in a few, such as Hungary, a prescription is required.
- It does not protect against sexually transmitted infections, and it does not replace regular contraception.
What exactly is emergency contraception?
Emergency contraception is a form of contraception that can help prevent pregnancy after sexual intercourse. Unprotected sex, a split condom, a missed contraceptive pill – in these situations the emergency contraceptive pill can help. The emergency contraceptive pill – as its name suggests – is a tablet that can help prevent an unwanted pregnancy. It is important to note, however, that it is not 100% protective; the sooner it is taken, the more effective it can be.
A common myth is also that this is an abortion pill – but that claim is not true. The pill works by delaying ovulation, which we cover in more detail a little later. It does not replace regular contraception and does not protect against sexually transmitted diseases – it is not recommended for frequent use; it is emergency help in unexpected situations.
Unprotected sex
72–120 hours
most effective when taken as soon as possible
Morning-after pill
Reduced risk of pregnancy
It does not protect against pregnancy 100% of the time, and it does not replace regular contraception.
When might emergency contraception be needed?
Emergency contraception can be a solution in situations where there is a risk of an unwanted pregnancy. It is not intended to replace regular contraception, but can be used in unexpected or unforeseeable situations.
In the following cases it is advisable to contact a health professional or to find out about the options as soon as possible:
The condom split or slipped off
The condom is one of the most widely used contraceptive methods, but it can split or slip off during use. In such cases sperm may enter the vagina, which can increase the chance of pregnancy.
Unprotected sex took place
If for any reason no contraception was used and there is a possibility of an unplanned pregnancy, emergency contraception can help reduce the risk.
A contraceptive pill was missed
The effectiveness of hormonal contraception may be reduced if one or more pills are missed, particularly during certain phases of the cycle. Whether emergency contraception is needed in such a case also depends on which week the pill was missed in, and on whether unprotected sex took place.
Vomiting or severe diarrhoea after taking the contraceptive pill
If vomiting or severe diarrhoea occurs within a few hours of taking the contraceptive pill, the medicine may not have been absorbed properly. This can reduce the effectiveness of the protection.
The contraceptive device failed
Certain contraceptive methods – such as a diaphragm, cervical cap or vaginal ring – may move, become damaged or be used incorrectly. In these cases too it is worth considering whether emergency contraception is needed.
Sexual violence
In the case of sexual violence, emergency contraception is one of the possible forms of medical care. In such a situation it is important that the person affected contacts a healthcare institution as soon as possible, where they can receive help not only in preventing pregnancy, but also with the necessary examinations, the prevention of infections and psychological support.
Important to know
Emergency contraception is more effective the sooner it is used. If there is a risk of pregnancy, it is not advisable to wait for symptoms to appear or for the next period – it is better to find out about the available options as soon as possible.
How does emergency contraception work?
The emergency contraceptive pill contains hormonal active substances that act on certain processes of the menstrual cycle. It is important to know that the morning-after pill is not effective in every case, and it works best if it is taken as soon as possible, preferably within the first 24 hours after intercourse.
To understand how emergency contraception works, it helps to know that several consecutive processes have to take place for a pregnancy to occur: ovulation, fertilisation, and then implantation of the fertilised egg. The morning-after pill acts primarily on the first of these processes.
Delaying or preventing ovulation
The primary mechanism of action of morning-after pills is delaying or preventing ovulation. The hormonal active substance they contain can prevent the egg from being released from the ovary.
This matters because if ovulation does not take place, sperm cannot fertilise the egg, so pregnancy cannot occur.
The product is therefore most effective if it is taken before ovulation. If ovulation has already occurred, the effectiveness of emergency contraception may be significantly reduced.
Important: the sooner the morning-after pill is taken, the greater the chance that it can delay or prevent ovulation.
Preventing fertilisation
In addition to delaying ovulation, some products may also influence the functioning of the female reproductive system. As a result, it may become harder for sperm to move and to reach the egg, which can further reduce the chance of fertilisation.
It must be emphasised, however, that the morning-after pill does not destroy sperm and does not guarantee that pregnancy is entirely ruled out. Effectiveness is influenced by a number of factors, such as the time elapsed since intercourse, the current phase of the menstrual cycle, and the type of product used.
It does not end an existing pregnancy
One of the most common myths is that the morning-after pill causes an abortion. This is not true.
Emergency contraception does not end an established pregnancy and has no effect on an embryo that has already implanted. If fertilisation and implantation have already taken place, the morning-after pill cannot interrupt this process.
Emergency contraception is therefore not the same as the abortion pill, and it cannot be used to end an existing pregnancy.
Within how much time should it be taken?
It is generally true that the sooner it is taken, the more effectively the pill protects against an unwanted pregnancy. For clarity, below you will find a summary of how emergency contraception works within the different time windows.
Which products are available, and how do they differ from each other?
The two most common active substances in emergency contraceptive pills are levonorgestrel and ulipristal acetate. Both aim to delay or prevent ovulation, but they can be used within different time windows, and their mechanisms of action are not entirely identical.
Important to know
The way these pills are obtained differs from country to country. In most of Europe both levonorgestrel and ulipristal acetate are dispensed in pharmacies without a prescription; in some countries, including Hungary, a doctor's prescription is still required. It is worth checking the local rules before you need them.
Products containing levonorgestrel
A morning-after pill containing levonorgestrel is generally taken within 72 hours, that is, within 3 days of unprotected sex. It is more effective the sooner it is taken, so it is not advisable to wait until the 72-hour limit.
It works primarily by delaying or preventing ovulation. If ovulation has already occurred, the effectiveness of the product may be significantly reduced.
Products containing ulipristal acetate
Ulipristal acetate can be used within a longer time window: within 120 hours, that is, within 5 days of unprotected sex. This does not mean, however, that it is worth waiting to take it – with this product too, use as early as possible is recommended.
Ulipristal acetate acts on progesterone receptors and may be able to delay ovulation even when the time of ovulation is already closer. For this reason it may be more effective than levonorgestrel in certain situations.
What is the most important difference?
The most important difference between the two products is the time window in which they can be used and their effectiveness in relation to ovulation. Levonorgestrel can generally be used within 72 hours, while ulipristal acetate can be used within up to 120 hours.
Choosing the right product, however, does not depend solely on the time elapsed since intercourse. Among other things, the following may matter:
- the current phase of the menstrual cycle,
- the expected time of ovulation,
- medicines taken regularly,
- hormonal contraception used previously,
- and in certain cases body weight and BMI as well.
So if you are unsure which option is appropriate in a given situation, it is advisable to consult a doctor or pharmacist.
Important: no morning-after pill offers 100% protection against pregnancy, none protects against sexually transmitted infections, and none replaces regular contraception.
For a clearer overview, you can also see the differences in the comparison table below.
Comparison of emergency contraceptive pills
The two most commonly available active substances: levonorgestrel and ulipristal acetate
LevonorgestrelWithin 72 hours (3 days) of unprotected sex.
Ulipristal acetateWithin 120 hours (5 days) of unprotected sex.
LevonorgestrelWorks primarily by delaying or preventing ovulation.
Ulipristal acetateActs on progesterone receptors and can delay ovulation even when the time of ovulation is closer.
LevonorgestrelMost effective when taken within the first 24 hours. Its effectiveness decreases as time passes.
Ulipristal acetateMay be effective for up to 120 hours, but the sooner it is taken, the greater the chance it will work.
LevonorgestrelIf ovulation has already occurred, its effectiveness may be significantly reduced.
Ulipristal acetateMay remain effective right up until ovulation approaches.
Levonorgestrel1.5 mg of levonorgestrel as a single dose.
Ulipristal acetate30 mg of ulipristal acetate as a single dose.
LevonorgestrelCertain medicines may reduce its effectiveness.
Ulipristal acetateCertain medicines may affect its effectiveness, and hormonal contraception can only be restarted with a delay after taking it.
LevonorgestrelIf less than 72 hours have passed since intercourse.
Ulipristal acetateIf 72–120 hours have passed, or ovulation is closer.
How effective is emergency contraception?
No form of emergency contraception offers 100% protection. How effective it is depends primarily on four factors: how much time has passed since intercourse, which product is used, where the body is in the cycle, and in part body weight as well.
Levonorgestrel taken within 72 hours prevented 84% of expected pregnancies in the clinical study.
Used within 72 hours, the pregnancy rate was 1.4% with ulipristal acetate and 2.2% with levonorgestrel.
The copper intrauterine device (copper IUD), fitted within 5 days, is the most effective emergency method.
What exactly does "84%" mean?
It does not mean that 84 out of 100 women do not become pregnant. It means that 84% of the pregnancies expected after unprotected sex did not occur. A single act of intercourse does not always lead to pregnancy in the first place, so the actual risk also differs from person to person and depending on the day of the cycle.
Time is the strongest factor
Both active substances are most effective if they are taken as soon as possible after intercourse. In an international study involving nearly 2,000 women, the pregnancy rate was 0.9% with ulipristal acetate and 2.5% with levonorgestrel taken within the first 24 hours.
The effectiveness of levonorgestrel decreases significantly after 72 hours, and according to international professional guidelines it can no longer be considered effective beyond 96 hours. In that case – between 96 and 120 hours – ulipristal acetate is the only pill that may still be considered.
The phase of the cycle: if ovulation has already occurred
Since both pills work by delaying or preventing ovulation, neither is effective if ovulation has already taken place. This is the most important limitation of the method, and also the reason why effectiveness cannot be given as a single figure that applies to everyone: the same pill is highly effective on one day of the cycle and no longer effective on another.
Body weight and body mass index
According to international professional guidelines, a body weight above 70 kg or a body mass index (BMI) above 26 may reduce the effectiveness of oral products – particularly that of levonorgestrel. In such cases the doctor may consider ulipristal acetate or a double dose of levonorgestrel. The effectiveness of ulipristal acetate may also decrease above a BMI of 30 (roughly 85 kg). Body weight does not affect the effectiveness of the copper IUD – it is advisable to discuss its insertion with a gynaecologist.
The data come from international clinical studies and from the WHO summary; the exact values may differ depending on the group studied and on the time of taking the product.
Important to know
Emergency contraception is an occasional solution. Regular contraceptive methods are considerably more reliable when used correctly, so if your current method often "slips", it is worth discussing the alternatives with a doctor.
What side effects may occur?
The side effects of the morning-after pill are usually mild and temporary. Because of the hormonal effect, however, the timing of the next period may change, and various unpleasant symptoms may occur for a few days. Side effects and their severity may differ from person to person.
The most common side effects
After taking the morning-after pill, the following symptoms, among others, may occur:
- nausea, sometimes vomiting,
- headache or dizziness,
- fatigue,
- lower abdominal pain or cramps,
- breast tension or breast tenderness,
- spotting or breakthrough bleeding,
- and changes to the next period.
The next period may come a few days earlier or later than usual, and the heaviness of the bleeding may also differ from the usual.
What happens if vomiting occurs?
If vomiting occurs shortly after taking the morning-after pill, the active substance may not have been absorbed properly. In such a case you should contact a pharmacist or doctor as soon as possible, because another dose may be needed. The exact time window depends on the product used, so it is worth checking its patient information leaflet as well.
When should you seek medical help?
Most side effects pass on their own within a short time. A medical examination may be warranted, however, if:
- severe or persistent lower abdominal pain occurs,
- unusually heavy or prolonged bleeding occurs,
- the period is significantly late,
- the pregnancy test is positive,
- or the symptoms are severe or do not pass.
It is particularly important to investigate severe lower abdominal pain and a late period occurring after use of the morning-after pill, because in the case of pregnancy the doctor must also rule out the possibility of an ectopic pregnancy.
Important to know
Spotting after the morning-after pill or a change in the timing of the period does not in itself prove that the product was effective. If pregnancy is a possibility, a pregnancy test and, if necessary, a medical examination are recommended.
What should you watch out for after taking the morning-after pill?
After taking the morning-after pill it is advisable to monitor your body's reactions and the timing of your next period. It is also important to know that the pill does not provide protection for any further unprotected sex during the rest of the cycle, so particular attention should be paid to using appropriate contraception afterwards.
Monitor your next period
Emergency contraception may temporarily change the menstrual cycle. The next period:
- may arrive a few days earlier or later,
- may be heavier or lighter than usual,
- breakthrough bleeding or spotting may also occur.
These changes do not necessarily indicate a problem in themselves.
When is it advisable to take a pregnancy test?
If your period is more than about a week late, is unusually light, or symptoms suggesting pregnancy occur, it is advisable to take a pregnancy test.
In order to reliably rule out pregnancy, it may also be warranted to take a test about 3 weeks after the unprotected sex if you are unsure about the timing of your next period.
Contraception is also needed the next time you have sex
It is a common misunderstanding that the morning-after pill provides protection until the next period. This is not the case. If further unprotected sex takes place after it is taken, there may again be a risk of pregnancy.
An appropriate contraceptive method should therefore be used during the rest of the cycle. If you use hormonal contraception regularly, what you need to do about continuing or restarting it also depends on which active substance the emergency contraception you used contained, so follow the product's patient information leaflet and the instructions of your doctor or pharmacist.
Do not forget about sexually transmitted infections
Emergency contraception serves only to reduce the risk of an unwanted pregnancy. It does not provide protection against sexually transmitted infections.
If there may have been a risk of infection during unprotected sex, it is advisable to consult a doctor about the necessary tests.
If vomiting occurred shortly after taking the pill, or if you have unusual, severe or persistent symptoms, you will find what to do and when to see a doctor in the section When should you seek medical help?
In brief
After taking it, monitor your period, take a pregnancy test if necessary, use appropriate contraception for any further sex, and see a doctor if you have unusual or severe symptoms.
Common myths
MythIt is an abortion pill
FactIt is not
MythIt causes infertility
FactIt does not cause infertility
MythIt can be used at any time
FactNo, it is effective for a maximum of 5 days
MythIt protects 100%
FactIt does not protect 100%
MythIt protects against STIs
FactIt does not protect against sexually transmitted infections
Frequently asked questions (FAQ)
How soon does emergency contraception need to be used?
Emergency contraception should be used as soon as possible; depending on the type of pill, it can generally be taken within 72 or 120 hours of intercourse.
Can you still get pregnant after taking the morning-after pill?
Yes. The morning-after pill does not provide 100% protection, so pregnancy can still occur after taking it.
What are the drawbacks of the morning-after pill?
It can cause temporary side effects such as nausea, headache, lower abdominal discomfort or changes to the menstrual cycle, and it is less reliable than regularly used methods of contraception.
How long does the morning-after pill stay in the body?
The active substance is largely cleared from the body within a few days, but its effect on the menstrual cycle may be noticeable for longer than that.
Is seven days after intercourse too late for emergency contraception?
For oral morning-after pills, seven days falls outside the 72–120-hour window, so it is best to speak to a doctor as soon as possible about the other options.
Can sperm survive after the morning-after pill is taken?
Yes. The morning-after pill does not destroy sperm; it reduces the chance of pregnancy mainly by delaying or preventing ovulation.
What can reduce the effect of the morning-after pill?
Its effectiveness can be reduced by taking it too late, by vomiting soon after taking it, and by the concurrent use of certain medicines and herbal preparations.
What should be avoided after taking the morning-after pill?
There are no general food or activity restrictions, but it is important to use contraception properly for any further intercourse, because the morning-after pill does not provide lasting contraceptive protection.
Which medicines should not be combined with the morning-after pill?
Some medicines – for example certain treatments for epilepsy, tuberculosis or HIV, as well as St John's wort – can affect how some emergency contraceptives work, so a doctor or pharmacist should always be told about them.
Which emergency contraceptive is best?
There is no single "best" product for everyone, because the right choice depends on the time that has passed since intercourse, the expected timing of ovulation, other medicines being taken and individual circumstances.
Is levonorgestrel or ulipristal acetate the better choice?
Ulipristal acetate can be used within a longer window of up to 120 hours and may be preferable in certain situations, but choosing the right product depends on individual circumstances.
How late can a regular contraceptive pill be taken?
This depends on the type of contraceptive pill, so the window stated in that product's patient information leaflet should always be followed.
Is it a problem if I take the emergency contraceptive pill four hours later?
This depends on the type of product: with some pills a delay of a few hours does not yet reduce protection, while other products require stricter timing.
What side effects can the morning-after pill have?
The most common side effects include nausea, headache, tiredness, lower abdominal pain, spotting and a change in the timing of the next period.
Can the morning-after pill be dangerous?
Emergency contraception can be used safely by most people, but side effects can occur, so a doctor should be consulted if severe or unusual symptoms appear.
Emergency contraception and online medical advice
Whether emergency contraception needs a prescription depends on where you live: in most of Europe it is sold over the counter, while in some countries – Hungary among them – a doctor's prescription is required. Because time matters so much here, it is worth asking for help as early as possible.
With AIP Clinic the process can be started online, without booking an appointment or waiting in a surgery. After registering you answer a few medical questions about your health and your situation, and a doctor reviews your case. If the doctor considers it medically appropriate and safe – and a prescription is required where you live – a prescription can also be issued.
You usually receive your personalised treatment plan, and the prescription if one is needed, within 24 hours. Care is 100% online, so you can ask for specialist help from anywhere.
Summary
Emergency contraception can be an important option in situations where unprotected sex has taken place, or where the chosen contraceptive method did not provide adequate protection. Time plays a key role in the effectiveness of the morning-after pill: the sooner it is used, the better the chance of reducing the risk of an unwanted pregnancy.
At the same time, it is important that the morning-after pill does not provide 100% protection, does not end an existing pregnancy, does not protect against sexually transmitted infections, and does not replace regular contraception. Choosing the right product and deciding what to do next may also depend on individual circumstances.
If unprotected sex has taken place, do not wait until your next period: seek personalised advice from a doctor or pharmacist as soon as possible. And if, after taking the pill, your period is significantly late, symptoms suggesting pregnancy occur or you have unusually severe complaints, take a pregnancy test and see a doctor.
Medical information: This article is for general information purposes and does not replace individual medical advice, diagnosis or treatment. If you have complaints or questions, consult a doctor or pharmacist.
Sources
- WHO – Emergency contraception (fact sheet)
- Cleveland Clinic – Morning-after pill
- PMC – Emergency contraception: mechanisms of action
- BMJ Sexual & Reproductive Health
- Contraception Journal
- Glasier A. et al.: Ulipristal acetate versus levonorgestrel for emergency contraception – The Lancet, 2010
- FSRH Clinical Guideline: Emergency Contraception (2017, updated 2023)
- European Consortium for Emergency Contraception – country-by-country information: ec-ec.org