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How to prevent pregnancy after sex

If you've had unprotected sex and are worried about getting pregnant, there are steps that you can take to decrease those chances.

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Safe sex—like many other things in life—isn’t foolproof. Maybe you had penis-in-vagina sex without some form of protection. Or maybe the form of protection you typically use didn’t work. Condoms break, pills get missed, and withdrawal (“pulling out”) isn’t perfect. 

While the chances of getting pregnant after one-time unprotected sex get higher the closer you are to ovulation, there are things you can do to prevent pregnancy (as well as some myths you might have heard that unfortunately don’t work as advertised).

The key thing to know is that, if you’re within 3-5 days of unprotected sex, emergency contraception can help you decrease those chances.

Below, we’re explaining all of your options for emergency contraception, including how each one of them works, how well they work, and where you can access them.

Emergency contraception

Emergency contraception is medication that can help you decrease the chances of pregnancy after unprotected penis-in-vagina sex or when birth control doesn’t work as planned. Emergency contraceptives are not “abortifacients” and don’t cause abortions. They help prevent pregnancy, but they can’t end a developing pregnancy. 

One of the ways that they work is by delaying ovulation until most or all of the sperm is gone—yes, sperm can live up to five days in the vagina! Because of this, if you have already ovulated then emergency contraception will not work. (This is one of the reasons why it does not have a 100% effectiveness rate.) This is also why it’s best to take emergency contraception as soon as possible: It will decrease the chance that you have ovulated already. 

Popular options for emergency contraception include:

  • Plan B and other emergency contraceptive pills (ECPs) that contain the hormone levonorgestrel (a progestin)
  • Ella, which contains ulipristal acetate (a chemical that blocks the effects of progestins)
  • Hormonal intrauterine devices (IUDs) that release 52 mg of levonorgestrel, like Mirena or Liletta
  • Non-hormonal IUDs (Paragard)
  • The Yuzpe method using combination birth control pills

Hey Jane’s team of providers can help you plan ahead, find the best emergency contraception for you, and get discreet access to Plan B or Ella to keep on-hand for whenever you may need them in the future.

The morning-after pill

The “morning-after pill” is probably the form of emergency contraception you’ve heard the most about. There are actually two available options for ECPs: ones containing levonorgestrel and ones containing ulipristal acetate.

Plan B and other ECPs containing levonorgestrel

Plan B and other ECPs containing levonorgestrel work by delaying ovulation. Delaying ovulation means there’s no egg available for fertilization by sperm. An egg needs to be fertilized by sperm and the fertilized egg needs to implant into the lining of the uterus for pregnancy to happen.

Levonorgestrel-based ECPs only work if taken before ovulation. When taken within three days of unprotected sex, they can prevent pregnancy for about 93-99 in 100 people. They can be taken up to five days after unprotectex sex, but they’re less likely to work. They’re more effective the earlier you take them.

Levonorgestrel-based ECPs may be less effective for people who weigh more than 165 pounds, but they can still work.

Levonorgestrel-based ECPs are easy to get. You can order them from online clinics like Hey Jane or pick them up at your local pharmacy.


Ella is an ECP that contains the chemical ulipristal acetate. While ulipristal acetate isn’t a hormone, it blocks the effects of progesterone on the body. Ella works by delaying ovulation. 

Ella only works if taken before ovulation. When taken within 120 hours (five days) of unprotected sex, it can prevent pregnancy for about 98-99 in 100 people, if they have not ovulated yet. When factoring in effectiveness for people who take it both before and after they’ve ovulated, that rate is between 85-95 in 100 people. It’s more effective the earlier you take it.

Ella may be less effective for people who weigh more than 190 pounds, but it can still work.

Ella is only accessible with a prescription from a health care provider. You can get a prescription for advanced provision of Ella from online clinics like Hey Jane (and we accept insurance and HSA/FSA funds).

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Hormonal IUDs contain the hormone levonorgestrel, while non-hormonal IUDs release copper ions. 

Hormonal IUDs work by thickening the cervical mucus, which makes it harder for sperm to get to an egg. They also work by preventing ovulation.

Non-hormonal IUDs work by affecting the way sperm move and making it harder for sperm to reach an egg. 

IUDs are the most effective form of emergency contraception. If inserted by a health care provider within five days of unprotected sex and no more than five days after ovulation, IUDs can prevent pregnancy for more than 99 in 100 people. The effectiveness of IUDs isn’t impacted by weight.

You have to visit a health care provider in person to get an IUD inserted. IUDs are one of the most effective forms of birth control and can prevent pregnancy for up to 3-10 or more years, depending on the type of IUD. (In fact, many people who get IUDs as emergency contraception end up liking them and keeping them as a method of birth control after.)

Can you use birth control as Plan B? 

Yes, you can use birth control pills as emergency contraception in what’s called the Yuzpe method. It’s the least effective form of emergency contraception, but it may be the only option available to some people. 

The Yuzpe method only works if it’s done before ovulation. Although it’s unclear exactly how the method prevents pregnancy, it delays ovulation and may lead to changes in hormone levels, the uterine lining, and cervical mucus.

Following the Yuzpe method requires taking two doses of whatever number of combination birth control pills you need to reach 100 mcg of ethinyl estradiol and 0.50 mg of levonorgestrel. You’ll take the doses 12 hours apart, but within three days of unprotected sex. This method will prevent pregnancy for about 56-86 in 100 people.

Since the Yuzpe method uses combined birth control pills, you’ll need a prescription from a health care provider to do it. If you have pills at home you would like to use for this method, just keep in mind that you will be short pills at the end of your pack!

Interested in trying out hormonal birth control as your primary method of contraception? Hey Jane’s team of providers can help you choose the right one for you from over 100 options, including the pill, the ring, the patch, and the shot.

Myths about emergency contraception

As with all things reproductive health, there are countless myths circulating about emergency contraception. Here’s the truth.

“Trending” natural alternatives

Despite what you may have seen or heard on TikTok, while there are many benefits to eating fruit, there’s zero scientific evidence that pineapple, papaya, or apricots will prevent pregnancy. 

(Interestingly, eating pineapple has also been suggested as a way to increase the chances of getting pregnant. There’s no scientific evidence of that either.)


No, douching after sex won’t prevent pregnancy. In fact, experts recommend avoiding it altogether. Douching can disrupt the bacterial environment of the vagina and increase the risk of vaginal infections like bacterial vaginosis.


While there may be other reasons why you’d want to pee after sex (it can help you reduce the risk of getting a urinary tract infection), peeing after sex won’t prevent pregnancy. 

Get tested for STDs and STIs

Something else to consider after unprotected sex is possible exposure to sexually transmitted infections (STIs). Getting regularly tested for STIs and being open with your partners about STI history can help reduce the risk of transmission.

If you are diagnosed with herpes, which is a very common STI, know that Hey Jane is here for you. We offer fast and discreet herpes treatment to help you stay on top of your sexual health and wellness.

If you don’t want to be pregnant

If you find out you're pregnant after unprotected sex and don’t want to be, you still have options. Hey Jane can help you access abortion pills safely, discreetly, and quickly—all from the comfort and convenience of your phone. Find out if a medication abortion is right for you.

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Written by

Sarah duRivage-Jacobs (MPH)

Sarah duRivage-Jacobs is a New York-based writer and editor of words dealing with reproductive health and abortion access. She received her Masters of Public Health degree in Community Health.

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