Emergency Contraception How To Choose Wisely

When the weekend passes and I open the clinic door on Monday, there are especially many emergency-contraception consultations. The question "We had relations on Saturday, but nowhere was open over the weekend so I couldn't come; a few days have passed—would it still work even now?" is almost never missing. Emergency contraception is, in a word, a race against time. Even in the same situation, the methods you can choose and their effectiveness change depending on how many hours have passed since intercourse. In this article, rather than the basic principles of emergency contraception, I will focus on the question I receive most often in the clinic—what is the smartest thing to choose at each time point.

The main way emergency contraceptive pills work is by delaying or preventing ovulation. Because you must catch up with and delay ovulation that is already in progress so as to throw off the timing at which sperm and egg meet, the sooner you take it, the higher the chance of success. The UK Faculty of Sexual and Reproductive Healthcare FSRH 2017 guideline and the American College of Obstetricians and Gynecologists ACOG 2015 materials both explain that oral emergency contraceptives are difficult to expect to be effective if taken after ovulation.

In the clinic, quite a few people give up in advance, saying "A few days have already passed, so it must be useless." But because the effective time window differs by method, there are often options remaining even if quite a bit of time has passed. So the first thing we check is the time of the last intercourse.

The emergency contraception methods currently available fall broadly into three. They are the two most commonly prescribed oral medications and the copper device inserted into the uterus. Each has a different effective time window and characteristics.

The FSRH 2017 guideline makes clear that both oral medications need to be taken only once, and that mixing the two drugs or increasing the dose does not raise effectiveness. In the clinic, too, we often get the question "Isn't it safer to take one more pill," but the principle is to take the one prescribed once.

Now let me organize what is reasonable according to the actual passage of time. The following are general medical criteria and may vary depending on individual circumstances.

• Within 72 hours: Levonorgestrel is the most familiar choice. However, since sooner is better, the key is not to delay.
• 72 to 120 hours: The evidence for levonorgestrel weakens as time passes. FSRH 2017 considers that beyond 96 hours it is in practice difficult to expect effectiveness, and recommends ulipristal or the copper device.
• Near 5 days or when you want the most certain method: The copper intrauterine device is reported as the most effective method, and it is also recommended by the WHO.

ACOG 2015 explains that ulipristal has room to delay ovulation even at the time of imminent ovulation, when secretion of luteinizing hormone LH has begun. This means it becomes an option even at a time point when levonorgestrel is no longer likely to work. If it is difficult to judge alone which drug is right, get a quick consultation on the method suited to your time point

If it is within 5 days of intercourse, that is, within 120 hours, copper intrauterine device insertion can be considered. ACOG 2015 and WHO materials explain that the copper device is the most effective emergency contraception method when medically appropriate, and some studies report cases of insertion at even later time points. Moreover, after insertion you can continue it as long-term contraception just as it is, so it is especially helpful for those who want to settle their next contraception at once.

When oral medication feels burdensome, or in situations where the effectiveness of oral medication may have declined because a lot of time has passed, the copper device becomes a reliable alternative. If you would like to re-examine your usual contraception method, it helps to look together at the pregnancy and contraception clinic or what types of contraception are available.

Even at the same time point, the better choice changes depending on your physical condition. Weight and drug interactions are representative examples.

It is reported that in cases of higher body weight, the effectiveness of levonorgestrel may be relatively reduced. ACOG 2015 explains that in those who weigh more, the failure rate of both oral medications may be higher, while noting that the effectiveness of the copper intrauterine device is not affected by weight. In such cases, ulipristal or the copper device comes to be considered first.

If you are taking medications that reduce drug efficacy, such as rifampin or carbamazepine, the effectiveness of oral emergency contraceptives may be reduced, so the copper intrauterine device is considered first. There is one more point we emphasize in the clinic. Because ulipristal may have reduced effectiveness if another progestogen component is used within 7 days before or 5 days after taking it, FSRH recommends waiting 5 days after taking ulipristal before restarting hormonal contraception.

Taking the medication is not the end. It is good to know a few situations in advance.

If you vomit within 3 hours of taking it, the drug may not be sufficiently absorbed and may be ineffective, so you take the same drug again immediately. For those with severe nausea, an antiemetic may also be prescribed together. Also, menstruation after emergency contraception may be earlier or later than usual, and if it is more than a week late from the expected date, it is safe to check whether you are pregnant.

Those who are breastfeeding also have many worries. In the past, because a small amount could be detected in breast milk after taking an emergency contraceptive pill, a 2-to-7-day suspension of breastfeeding was sometimes recommended, but the latest FSRH 2025 materials state that you do not need to suspend breastfeeding after a single dose of ulipristal. However, adjustment may be needed depending on individual circumstances such as the postpartum time point, weight, underlying conditions, and the next contraception plan, so we recommend also checking the taking emergency contraceptive pills while breastfeeding content.

This is a point many people misunderstand, so let me make it clear. Emergency contraceptive pills are not abortion pills. Because their main mode of action is to delay or suppress ovulation, they are not drugs that terminate an already established pregnancy. That is why the time point matters, and why, once ovulation and fertilization are already over, it is difficult to prevent with oral medication.

One more thing: emergency contraceptive pills are strictly for emergency situations and do not replace regular contraception. In clinical experience, the more someone repeats emergency contraception, the much more stable it is to newly establish a regular contraception plan. If contraception-method concerns keep recurring, we recommend taking this opportunity to design a method that suits you together.

Emergency contraception is a race against time, but having a little time pass does not mean there is no method at all. If you tell us exactly the time of your last intercourse and your physical condition, we can find together the most reasonable method to match. Consult about the emergency-contraception method suited to your current situation

Written by: Lee Dong-hee Director · Obstetrics and Gynecology Specialist · View medical staff profile

First published November 26, 2025 · Last reviewed May 30, 2026

References: FSRH Guideline Emergency Contraception (2017, amended 2025), ACOG Practice Bulletin Emergency Contraception (2015), WHO Emergency Contraception (2021)

This article is intended to provide general health information and does not replace individual diagnosis or treatment. If you have symptoms, please consult through a medical visit.