What is Emergency Contraception? Gynecologists Answer 10 Common Questions About this Type of Birth Control

There are four types of emergency contraception, each of which differs in terms of side effects, effectiveness, cost, and how it works.

Whether you forgot the condom altogether or noticed the one you used broke, unprotected sex happens to the best of us. The good news is emergency contraception—sometimes called the morning-after pill—can help prevent unwanted pregnancies when used in a certain time frame after sex.

Here's what you need to know about emergency contraception, including how it works, which type is best for you, and when to use it.

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1. What is emergency contraception?

Emergency contraception is a form of birth control that reduces the chance of pregnancy if used soon after having unprotected sex, Nahia Jean Amoura, MD, a professor of obstetrics and gynecology at the University of Nebraska Medical Center, tells Health.

There are four main types of emergency contraception:

  • Paragard (copper) IUD, which requires a prescription and must be inserted and removed in-office by a health care provider.
  • Hormonal IUDs, like Liletta or Mirena, which also require a prescription and in-office visits for insertion and removal.
  • Ella (ulipristal), a prescription pill that can be picked up at pharmacies or delivered to your home via an online pharmacy.
  • Levonorgestrel pills, with brand names like Plan B, Take Action, and Aferta, which do not require a prescription and can be found at most drugstores.

"Emergency contraception can be used anytime that you have sex that puts you at risk of pregnancy," Kate White, MD, MPH, vice chair of academics at Boston Medical Center and an associate professor of obstetrics and gynecology at Boston University School of Medicine, tells Health. This includes sex where either:

  • No contraception was used
  • Contraception was used, but you aren't sure you used it correctly—such as missing multiple birth control pills in a month or potentially leaving your birth control ring out for too long.
  • Contraception was used, and you know it failed—say the condom slipped off or broke.

It's important to note that emergency contraceptives will not protect against sexually transmitted infections (STIs).

2. How does emergency contraception work?

For starters, emergency contraception is not the same as abortion. That's because it works by preventing pregnancy, not by interfering with an already existing one, Dr. Amoura says. In fact, emergency contraception will not work if pregnancy has already occurred, and it will not harm the fetus if you are pregnant.

"Emergency contraception either works or it doesn't. It doesn't cause birth defects or a miscarriage," Dr. White says.

Exactly how emergency contraception works depends on which type you use. For example, the two pill options—ella or levonorgestrel pills, such as Plan B—are basically high-dose versions of the hormones found in regular birth control pills. "Both seem to work the same way by stopping ovulation that might be due to happen in the next few days," Dr. Amoura says. Without ovulation, there's no egg for sperm to fertilize.

Even if you've already ovulated, the pills still prevent pregnancy by interfering with how sperm move or by keeping a fertilized egg from attaching to the uterus wall, Dr. Amoura says. "In medical terms, a fertilized egg that has not been implanted does not qualify as a pregnancy," she adds.

Meanwhile, both IUDs—which are small pieces of flexible, T-shaped plastic inserted into the uterusprevent pregnancy by making the uterus a hostile environment for sperm. They do so by interfering with how sperm move and thickening cervical mucus so it's more difficult for sperm to reach the egg. While the Paragard IUD uses copper to achieve this affect, hormonal IUDs use levonorgestrel.

Once you get your period—which signals the IUD worked—a health care provider can remove it, Dr. White says. You also have the option to keep the IUD as a long-term form of birth control, since Paragard is effective for 12 years and hormonal IUDs are effective for six to seven, depending on the brand.

4. How effective is emergency contraception?

When used as directed, emergency contraception is extremely effective at preventing pregnancy. In fact, IUDs are the most effective form of emergency contraception, preventing more than 99% of pregnancies, according to Planned Parenthood. Meanwhile, ella is 85% effective and levonorgestrel pills are 75% to 89% effective.

Unfortunately, research indicates both morning-after pills are not effective if you are over a certain BMI. For example, Plan B may not work if you have a BMI over 26, and ella may not work if you have a BMI over 35, Dr. White says. The good news is, neither IUD has a weight limit. However, if you can't get an IUD or you really don't want one, Dr. White recommends taking one of the morning-after pills.

"Not being effective isn't the same as hurting you," she explains. "So, if Plan B or ella is the only thing you can get your hands on I would say try anyways."

5. When should I take emergency contraception?

The time frame in which emergency contraception will be effective depends on the type of emergency contraception you use. For example, both IUDs will prevent pregnancy if inserted within 5 days (120 hours) of having unprotected sex. They also remain as effective on day one as they do on day five.

If you choose a morning-after pill, you should take it as soon as possible, since its effectiveness decreases over time, Dr. Amoura says. For example:

  • Ella can be taken up to five days after having sex, but its effectiveness diminishes over time. Therefore, it should be taken as soon as possible.
  • Levonorgestrel pills, like Plan B, should be taken within three days (72 hours) of having unprotected sex. However, like Ella, it is less effective the longer you wait.

6. What are the side effects of emergency contraception?

Depending on the type of emergency contraception you use, you may experience some unpleasant but mild side effects, Dr. Amoura says.

If you opt for the copper IUD, you may have spotting and your next period may be heavier and longer than normal, Dr. White explains. Increased cramping and back pain are also common. Hormonal IUDscan also cause spotting, but your next period will not be heavier, and cramping doesn't get worse.

According to the American College of Obstetrics and Gynecology, side effects of the morning-after pill include:

"[Side effects] are not very common, and if they happen, they usually only last two or three days," Dr. White says.

7. Can emergency contraception make your period late?

Emergency contraception, particularly morning-after pills, can change the timing of your next period: It may come on time, or a bit earlier or later than usual.

"Your next period might be weird, but after that, it resets back to your regular cycle," Dr. White says. "If you haven't had a period four weeks after taking emergency contraception, you should take a pregnancy test to be safe."

8. How much does emergency contraception cost?

The price tag of your emergency contraception will depend on the type you choose. In general, levonorgestrel pills cost between $11 and $45, with Plan B at the higher end: about $40 to $50, according to Planned Parenthood. One of the downsides of having Plan B available over-the-counter is that "insurance is less likely to cover it," Dr. Amoura says.

However, most insurance plans will cover ella, which costs about $50 in-store without insurance and $90 when ordered online (including the price of medical consultation and overnight shipping).

Meanwhile, IUDs can range from $0 to $1,300 depending on your insurance, says Planned Parenthood. "Insurances that cover IUDs for contraception will also cover IUDs as an emergency contraceptive," Dr. White says.

9. How many times can you take emergency contraception?

If you have an IUD and decide to keep it, you won't have to take emergency contraception for the next 6-12 years. You can take morning-after pills as many times as is necessary since there are no long-term risks. "It's the same risk as using any other contraceptive," Dr. White says.

However, taking emergency contraceptive pills multiples times a month will mess with your cycle and cause irregular and unpredictable bleeding, Dr. White points out. That's why health care providers recommended most people don't use morning-after pills in place of regular birth control. Doing so will also cost more in the long run than using other methods like the pill or an IUD, Dr. Amoura says. Although, people who rarely have sex that exposes them to pregnancy-risk—such as those who don't identify as heterosexual or may be in long-distance relationships—morning-after pills may be the only birth control method they need, Dr. White says.

10. Which emergency contraception is right for me?

Whatever emergency contraception you choose will depend on your own unique circumstances. For example, if it's already been three days since you had unprotected sex, then ella may be the best option for you. Or maybe you choose Plan B since you can't get a prescription in time. Perhaps you have a higher BMI, in which case an IUD would be your safest bet.

If you are unsure which emergency contraception is right for you, call your primary care physician or ob-gyn. They can help you make the best decision for you and your body.

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Updated by
Amanda Gardner
mandy gardner

Amanda Gardner is a freelance health reporter whose stories have appeared in cnn.com, health.com, cnn.com, WebMD, HealthDay, Self Magazine, the New York Daily News, Teachers & Writers Magazine, the Foreign Service Journal, AmeriQuests (Vanderbilt University) and others. In 2009, she served as writer-in-residence at the University of Wisconsin School of Medicine and Public Health. She is also a community artist and recipient or partner in five National Endowment for the Arts grants.

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