What is emergency contraception?

A condom broke, you missed a pill, or sex happened when you did not plan for it. In those moments, you might immediately wonder, “what is emergency contraception, and is it too late to do something?” Emergency contraception gives you a second chance to prevent pregnancy after unprotected sex or birth control failure, and it is more accessible and safer than many people realize.

This guide walks you through what emergency contraception is, how it works, which options you have, and what to expect next so you can act quickly and feel more in control.

Understanding emergency contraception

Emergency contraception is any method you use after sex to lower your chance of getting pregnant. It does not end a pregnancy that has already started. Instead, it helps prevent a pregnancy from occurring in the first place.

You might use emergency contraception if:

A condom broke or slipped off
You forgot to take your birth control pills or took them late
You had sex without any birth control
You were forced to have sex or experienced sexual assault

Medical organizations like the American College of Obstetricians and Gynecologists describe emergency contraception as a “backup” option, not a replacement for regular birth control (ACOG).

Types of emergency contraception

When you ask “what is emergency contraception,” you are really asking about a few different methods. In the United States, there are two main categories: emergency contraceptive pills and the copper IUD used as emergency contraception.

Emergency contraceptive pills

Emergency contraceptive pills are sometimes called “the morning after pill.” Despite the name, you do not have to wait until morning. The sooner you take them after sex, the better they work.

There are three main kinds:

Levonorgestrel pills
These are one‑dose pills you take as soon as possible within 72 hours, or 3 days, after unprotected sex. Some brand examples include Plan B One‑Step and generics like Fallback Solo. They are available over the counter without a prescription in the United States (Mayo Clinic, Cleveland Clinic).
Ulipristal acetate pills
Often sold under the brand name ella, this pill stays effective up to 120 hours, or 5 days, after unprotected sex and does not lose effectiveness as quickly over time. You need a prescription for ulipristal in the United States (ACOG, Mayo Clinic). Research shows that between days 3 and 5, ulipristal works better than levonorgestrel pills (CDC).
Combined estrogen and progestin pills
This older method uses certain regular birth control pills in higher doses. It is less effective and more likely to cause nausea and vomiting than levonorgestrel or ulipristal, so it is usually considered a backup to the other pill options (CDC).

All morning after pills work mainly by delaying or preventing ovulation, which means they stop your ovaries from releasing an egg during that cycle (Mayo Clinic, Cleveland Clinic, WHO).

Copper IUD as emergency contraception

The copper intrauterine device, often called a copper IUD, is another highly effective form of emergency contraception. A healthcare professional places it in your uterus within 5 days of unprotected sex.

According to the World Health Organization, the copper IUD is more than 99 percent effective at preventing pregnancy when used this way and is considered the most effective emergency contraception available (WHO). It works by releasing copper, which is toxic to sperm, so sperm cannot fertilize an egg.

The copper IUD also doubles as long‑term birth control for up to 10 years and can be removed at any time if you decide you want to try to get pregnant or switch methods (ACOG, WHO).

How emergency contraception works

To understand what emergency contraception is doing in your body, it helps to think about the steps that have to happen for pregnancy to occur:

Your ovary releases an egg
Sperm meet and fertilize that egg
The fertilized egg implants in your uterus

Emergency contraceptive methods target the early part of that process.

Pills: pausing ovulation

Emergency contraceptive pills, both levonorgestrel and ulipristal, primarily:

Delay or block ovulation
Make it harder for sperm and egg to meet

If you have already ovulated and fertilization has occurred, current evidence shows that these pills do not disrupt an existing pregnancy and do not cause an abortion (Mayo Clinic, Cleveland Clinic, WHO).

Copper IUD: stopping fertilization

The copper IUD releases copper ions into your uterus. These create an environment that:

Damages sperm so they cannot move well
Reduces the chance that sperm can fertilize an egg

Like emergency contraceptive pills, the copper IUD prevents a pregnancy from starting. It does not interrupt an established pregnancy and does not harm a developing embryo (WHO).

When you should use it

Timing makes a big difference in how well emergency contraception works. The general rule is simple: the sooner, the better.

According to the World Health Organization, you can use emergency contraception up to 5 days after unprotected sex for all recommended methods, but effectiveness is highest when taken or inserted as soon as possible (WHO).

Here is a quick timing guide:

Levonorgestrel pills: Best within 72 hours, can be used up to 120 hours but become less effective each day (Cleveland Clinic, Mayo Clinic)
Ulipristal acetate: Effective up to 120 hours and does not lose much effectiveness over that time (ACOG, CDC)
Copper IUD: Over 99 percent effective when inserted within 120 hours after sex (WHO)

You can use emergency contraception more than once in a menstrual cycle if needed, but it is meant as a backup method. For ongoing protection, it is a good idea to talk with a clinician about regular birth control options after you have handled the immediate situation (Cleveland Clinic).

Safety, side effects, and myths

Emergency contraception has been studied for many years and is considered safe for most people of reproductive age, including teenagers (WHO).

Common side effects

With emergency contraceptive pills, you might notice:

Nausea or mild stomach pain
Headache
Dizziness or fatigue
Breast tenderness
Light spotting
A period that comes a little earlier or later than usual

The Mayo Clinic notes that your next period might be delayed by up to one week. If it is more than three weeks late, taking a pregnancy test is recommended (Mayo Clinic). Copper IUD insertion can cause brief cramping, and some people notice heavier or more painful periods, especially in the first few months.

Myths to let go of

A lot of confusion still surrounds emergency contraception. Here are some key clarifications based on current medical guidance:

It does not cause an abortion. Emergency contraceptive pills work before pregnancy begins. They do not end an existing pregnancy (Cleveland Clinic, WHO).
It does not harm future fertility. Using emergency contraception does not make it harder for you to get pregnant in the future (Cleveland Clinic).
It is not meant for regular use. While you can use it more than once, it is less effective than most daily or long‑acting birth control methods and is meant for emergencies only (Cleveland Clinic, Mayo Clinic).
It does not protect against STIs. Emergency contraception only helps prevent pregnancy. It does not protect you from sexually transmitted infections, including HIV, so condom use and other prevention methods like PrEP are still important if you are at risk (CDC).

There is also evidence that body weight can affect how well pills work. If you have overweight or obesity, clinicians often recommend the copper IUD as the most reliable option (ACOG, Cleveland Clinic).

If you are not sure which method is best for you, contacting a clinic, telehealth service, or pharmacist as soon as possible can help you choose quickly and confidently.

Choosing the right option for you

The best form of emergency contraception for you depends on a few key questions:

How long has it been since you had unprotected sex?
Do you have access to a prescription or a clinic visit right now?
Are you looking for long‑term birth control too?
What is your body weight and health history?

Here is a simple way to think about it:

If you want the most effective option and long‑term protection, a copper IUD within 5 days is your best bet, as long as you can get to a provider who can insert it (WHO, ACOG).
If it has been more than 3 days but less than 5 days, ulipristal acetate generally works better than levonorgestrel pills (CDC).
If you need something immediately and cannot see a clinician today, an over‑the‑counter levonorgestrel pill from a pharmacy is usually the fastest solution.

After using emergency contraception, you can usually start or resume a regular birth control method right away, although there are some timing nuances if you take ulipristal. A healthcare professional can guide you through this so you stay protected going forward (ACOG, CDC).

What to expect afterward

Once you have taken an emergency contraceptive pill or had a copper IUD inserted, your body may need a short time to adjust.

You can expect:

Mild side effects that usually pass within a couple of days
A period that is slightly earlier, later, lighter, or heavier than usual
The need for a backup method, like condoms, if you have more sex soon and are not yet on regular birth control

If your period is more than one week late, or if you have symptoms of pregnancy, such as nausea or breast tenderness that continue, take a pregnancy test and consider following up with a healthcare professional (Mayo Clinic).

If you had sex without a condom, or a condom broke, you might also want to ask about STI testing. Since emergency contraception does not prevent infections, pairing it with STI screening can help protect your overall sexual health (CDC).

Key takeaways

Emergency contraception is a safe, effective way to reduce your chance of pregnancy after unprotected sex or birth control failure.
Your main options are morning after pills and the copper IUD, which is the most effective method and can double as long‑term birth control (WHO, ACOG).
Morning after pills like levonorgestrel and ulipristal work best when taken as soon as possible and do not cause abortion or affect future fertility (Mayo Clinic, Cleveland Clinic, WHO).
None of these methods protect you from STIs, so condom use and regular testing still matter for your health (CDC).

If you think you need emergency contraception right now, your best next step is to act quickly. Visit a pharmacy, contact a clinic or telehealth provider, or reach out to a trusted healthcare professional so you can get the method that fits your situation and feel more at ease about what comes next.