Get an A+ in Plan B and emergency contraception

Eva Marie Luo, MD, MBA, FACOG - Contributor Avatar

Written by Jess Sims 

Eva Marie Luo, MD, MBA, FACOG - Contributor Avatar

Written by Jess Sims 

last updated: Aug 26, 2021

8 min read

If your regular birth control method fails or you, for whatever reason, didn't end up using contraception during penile-vaginal sex, there's a safe and effective way to prevent pregnancy: emergency contraception (EC). According to the CDC, nearly one in four people with ovaries ages 20-24 have used an emergency contraceptive at least once — so if you've used one, you're far from alone.

Various methods of EC have been around for decades. Human clinical trials of estrogen-only EC were taking place in the 1960s, and hormonal birth control has been used off-label for EC since then. In 1999, the FDA approved Plan B, which instead uses a progestin (levonorgestrel) — this is the most well-known form of EC, and what people often call “the morning-after pill.” Emergency contraceptive pills (ECPs) like Plan B became widely available over the counter by the mid-2000s, increasing access for those who need them.

We know there’s a lot of information out there (it is the internet, after all), so we want to set some things straight and give you the nitty-gritty on all things emergency contraception. Before we dive into the who, what, where, and when of options like Plan B, there's one thing we have to clear up first: Emergency contraception is not an abortifacient and will not abort an existing pregnancy.

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The biggest takeaways

  • Emergency contraception is a safe and effective way to prevent pregnancy after unprotected sex or birth control failure.

  • There are four main forms of emergency contraception: Over-the-counter pills containing levonorgestrel (like Plan B), ulipristal acetate (under the name ella), temporary higher doses of birth control pills (this is called the Yuzpe Method), and the copper IUD.

  • Emergency contraception pills (ECPs) have 75%-89% effectiveness at preventing pregnancy if taken within 72 hours (three days) of unprotected sex, ulipristal acetate is at least 75%-89% effective for up to 120 hours (five days), the Yuzpe Method is 56%-86% effective for up to 72 hours, and the copper IUD is almost 100% effective if inserted within 120 hours.

  • ECPs are less effective for people with higher body-fat percentages. Copper IUDs are the most effective and work better for more people.

  • Emergency contraception does not cause abortions and won't impact your fertility in the long run, regardless of type.

What exactly is emergency contraception? And how effective is it?

Although Plan B may be synonymous with “emergency contraception,” it’s actually one of several in a class of emergency contraception pills (ECPs) that contain levonorgestrel (LNG), a progestin. Other options in this category include Fallback Solo, Opcicon One-Step, and Next Choice One Dose.

Since all of the above ECPs contain the same active ingredient, despite being called “morning-after pills,” they're all 75%-89% effective at preventing pregnancy if taken within 72 hours (three days) of unprotected sex. The great thing about Plan B and other ECPs with LNG is that you can get them right over the counter, which makes it easier to take them at the right time.

But ECPs with LNG (acronym overload, we know) aren’t the only forms of emergency contraception:

  • Ulipristal acetate is sold under the brand name ella (that lowercase "e" is intentional) and requires a prescription from your healthcare provider. If taken within 72 hours of unprotected sex, ulipristal acetate has at least the same effectiveness as ECPs with LNG (75%-89%) — but it maintains that same level of effectiveness up to 120 hours (five days) after unprotected sex.

  • The Yuzpe Method of emergency contraception is taking two doses of combined oral contraceptives, which are your typical birth control pills containing both estrogen and progestin, at one time. This method is 56%-86% effective as emergency contraception if done within 72 hours of unprotected sex.

  • The copper intrauterine device (IUD), which is a procedure, can be used as emergency contraception if it's inserted within 120 hours of unprotected sex. The copper IUD is almost 100% effective as emergency contraception. Bonus: You'll now have extremely effective contraception that lasts for up to 10 years!

Why all the hype around Plan B when there are other options out there? "Easy access and brand recognition," explains OB-GYN and Modern Fertility medical advisor Dr. Eva Luo, MD, MBA. Plan B is also easier to explain than, for example, increased dosage of a birth control pill. However, says Dr. Luo, "Many OB-GYN offices feel comfortable prescribing the other options or counseling the options via phone/video," which improves access. In terms of the copper IUD in particular, they're a great choice for people who are also looking for an extremely effective form of long-acting contraception. "The second bonus is that if patients are trying to avoid hormones, unlike the other forms of EC, this is non-hormonal," she adds — though she wouldn't recommend a copper IUD for those who have a baseline of heavy or crampy periods.

How does emergency contraception work?

Exactly how emergency contraception works depends on the kind you're using:

  • Plan B and other ECPs with LNG: ECPs containing LNG work by blocking ovulation and the thickening of the cervical mucus, putting two obstacles in the way of sperm meeting up with egg after unprotected sex.

  • Ulipristal acetate (aka ella): If ulipristal acetate is taken before ovulation, it delays or blocks ovulation — thereby making sure an egg isn't available for fertilization. If it's taken after ovulation, it can prevent the endometrium (uterine lining) from thickening to make it less hospitable for implantation of a fertilized egg.

  • The Yuzpe Method: Like birth control pills during typical use, the Yuzpe Method works by blocking ovulation and possibly implantation of a fertilized egg.

  • The copper IUD: This non-hormonal IUD works by releasing copper ions into your cervix, making your uterus an unwelcoming home for sperm.

How do you take emergency contraception?

Perhaps unsurprisingly, the form of emergency contraception you use dictates exactly how and when you take it.

Here's how to take Plan B or other ECPs with LNG:

  • Buy an ECP over the counter (or through some online pharmacies). The ECP may come in either one pill or two.

  • Always be sure to refer to the package for instructions. Typically, you'll take the first (or only) pill as soon as possible within the first 72 hours for the highest effectiveness.

  • If your ECP has a second pill, the general guidelines are to take it 12 hours later.

  • If you vomit within one to two hours of taking either of the pills, you may need to ask a healthcare professional about taking another one.

How to take ulipristal acetate:

  • Talk to your healthcare provider about getting ulipristal acetate prescribed or explore online pharmacies.

  • Take one tablet as soon as possible, or within 120 hours of unprotected sex.

How to follow the Yuzpe Method:

  • This method uses the birth control pills you already have.

  • Depending on your pill type, there are specific dosing regimens that should be followed within 72 hours of unprotected sex.

How to use a copper IUD for emergency contraception:

Dr. Luo explains that timing for emergency contraception is likely the hardest part of the process for many people. Taking the emergency contraception within that 72- or 120-hour window "can sometimes be hard given access or even awareness that you have options," she says. Dr. Luo emphasizes these two points when talking to patients about emergency contraception: "Take it ASAP after you have realized that you have had unprotected intercourse (i.e., don't wait until hour 71 to take it), and take a pregnancy test in two weeks."

Does emergency contraception have any side effects?

As with most medications, the answer is yes across emergency contraceptive types. The most commonly reported side effects for both ECPs with LNG and ulipristal acetate include:

  • Nausea

  • Dizziness

  • Tiredness

  • Headache cramps

  • Some bleeding between periods

  • Heavier menstrual bleeding

If you're using the Yuzpe Method for emergency contraception, nausea and vomiting are commonly experienced.

For the most part, these side effects only last a few days. If side effects last longer or you have other, more severe side effects, stop what you’re doing and go see a doctor.

While the copper IUD doesn't have as many side effects as hormonal emergency contraceptive options, you might experience some of the following:

  • Some bleeding between periods

  • Cramps

  • More severe menstrual pain

  • Heavier menstrual bleeding

Can using emergency contraception impact your fertility?

One common misconception is that ECPs affect your fertility or you can take them “too many times.” The American College of Obstetricians and Gynecologists (ACOG) says you can take ECPs multiple times, even more than once in a single menstrual cycle, with no impact on your long-term fertility. ECPs are not recommended, though, for regular use as your primary birth control because it won't be as effective as other options.

Copper IUDs also won't impact your fertility in the long run. According to a 2015 study of 69 former IUD users (50 of which were copper) and 42 former non-IUD users, there was no difference in the time to pregnancy in IUD users compared to non-IUD users. One notable distinction here, though, is that copper IUDs are designed to be a primary form of birth control.

"While you can take ECPs several times without it affecting your fertility, it's not sustainable," explains Dr. Luo. She recommends using a visit with your healthcare provider for ECPs or other emergency contraception to "talk about a contraceptive plan moving forward."

Is there anyone who shouldn't use emergency contraception?

When taken correctly and within the 72-hour window, ECPs with LNG are pretty effective in helping to prevent pregnancy — as high as 89% effective. But there’s a caveat: Weight can play a role in its effectiveness.

In 2011, a large study conducted in the European Union found that levonorgestrel-based contraception seemed to lose its effectiveness in participants weighing 165 pounds or more. In participants weighing 175 pounds, it didn’t seem to work at all. Since then, there's been quite a bit of discussion and further research. The FDA currently takes this stance on the topic:

“The FDA has completed a review of available scientific data concerning effectiveness of levonorgestrel (LNG) emergency contraceptives (ECs) in women who weigh more than 165 pounds or have a BMI of more than 25 kg/m2. Because these data are conflicting and too limited to make a definitive conclusion, the FDA does not believe that a change in the labeling for LNG EC products is warranted at this time.”

Despite the FDA's decision not to update labeling for ECPs with LNG, the researchers behind the aforementioned study concluded that copper IUDs are the best option for people whose body-mass index — aka BMI, a flawed measurement tool commonly used by the medical community to estimate body-fat percentage — is above 25. (Ulipristal acetate may also be less effective for people with higher body-fat percentage.) Unfortunately, since copper IUDs are only available via procedure, that may mean that access is an issue for some.

"For my patients who have a BMI >25, it's important to mention this caveat," says Dr. Luo. "It is all about a balance between the risk of pregnancy and ease of access when it comes to counseling a patient about the role of weight and the form of EC they choose."

How much does emergency contraception cost? And does insurance cover it?

The cost of emergency contraception can be prohibitive for some: Over-the-counter Plan B One-Step is $40-$50 in most retail stores without insurance. That said, other less well-known brands with the same active ingredient and efficacy (like Take Action or My Way) can be as low as $11 per dose.

You can get ulipristal acetate through your healthcare provider or online for $90 without insurance. Getting a copper IUD could range from $0-$1,300, depending on whether or not you have insurance.

All forms of emergency contraception should be covered by your insurance plan if prescribed by your healthcare provider (which they can do for even the over-the-counter options) — though, as we'll cover in the next section, this might be an issue in certain states.

If you need access to low-cost or free emergency contraception, check with the closest Planned Parenthood.

Where can you find emergency contraception?

When it comes to emergency contraception (and many other things in the world of reproductive health), all access is not created equal. The Guttmacher institute keeps a running list of how easy it is to access emergency contraception in the 50 states and Washington, DC. Arizona, Arkansas, Georgia, Idaho, Illinois, Mississippi, and South Dakota all have state laws that prohibit access to emergency contraception.

Even in the states with restrictions, providers should still be able to prescribe emergency contraception, says Dr. Luo. But she makes sure to proactively send her patients home with a few prescriptions for emergency contraception just in case.

In most states, however, ECPs with LNG should be available over the counter at pharmacies. You'll have to talk to your healthcare provider or use an online pharmacy (only in the case of ulipristal acetate) to get prescription emergency contraception.

Ultimately, timing is the most important thing here — but know your OB-GYN or healthcare provider is always there to support you, and may be able to offer emergency contraception prescriptions through telemedicine.

The bottom line

In short, emergency contraception is safe, effective, and accessible for the majority of people in the US. It is not an abortion pill, and it will not affect your long-term health or fertility. Things can happen — know that you have options.

If you still need a longer-term method of contraception, check out our articles on the most popular methods out there. Modern Fertility's always here to support you with clinically sound info so you can make the right decisions for you.

This article was medically reviewed by Dr. Eva Marie Luo, MD, MBA, OB-GYN at Beth Israel Deaconess Medical Center and Clinical Lead for Value at the Center for Healthcare Delivery Science at Beth Israel Deaconess Medical Center.


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

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Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

August 26, 2021

Written by

Jess Sims

Fact checked by

Eva Marie Luo, MD, MBA, FACOG

About the medical reviewer