Emergency Contraception | University Health Service

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What is emergency contraception?

Emergency contraception (EC) is a method used to prevent pregnancy after unprotected vaginal sex or when your method of birth control fails. Depending on the type of emergency contraception, it may be effective up to 5 days after unprotected sex, but it is most effective within the first 12-24 hours. It is intended for emergency situations and does not protect against sexually transmitted infections (STIs).

There are three main types of EC, and this page will focus primarily on ella® and Levonorgestrel.


  • 85% effective up to 120 hours after unprotected sex
  • Requires a prescription

Levonorgestrel (e.g. Plan B One-Step™, Next Choice®, and other brands)

  • 89% effective up to 72 hours after unprotected sex; continues to reduce risk of pregnancy up to 120 hours but with decreasing effectiveness.
  • Available without prescription (over-the-counter)

ParaGuard (copper IUD)

  • 99.9% effective up to 120 hours (5 days) after unprotected sex
  • Requires a prescription and a visit to a health care provider for insertion
  • Provides ongoing contraception for up to 10 years
  • See IUDs for more information.

EC may be used if:

  • You had sex without using any type of birth control method.
  • Your primary birth control method failed. For example, the condom broke and your partner ejaculated into your vagina.
  • You were forced to have unprotected sex. (See the U-M Sexual Assault Survivor website for resources and information)

How does emergency contraception work?

EC consists of one of the two hormones found in birth control pills — progestin. The release of this hormone into your body helps to keep your ovaries from releasing an egg and thickens your cervical mucus to prevent sperm from joining with an egg in the uterus. Progestin also thins the lining of the uterus to keep a fertilized egg from attaching to the uterus.

EC does not cause an abortion. The “morning-after pill” (ella® or Levonorgestrel) is NOT the “abortion pill” RU-486. If you are already pregnant, emergency contraception will not end your pregnancy. If you think you may be pregnant, talk to your health care provider.

How do I use emergency contraception?

Following package directions, take EC as soon as possible after unprotected sex. The sooner you start the EC, the more effective it is in preventing pregnancy. Eating a snack or drinking a glass of milk can help reduce nausea.

EC is taken as one or two doses or pills, depending on the product. Take the first pill as soon as possible and, if there is a second pill, you may take it 12 hours later, or take it at the same time the next day.

How effective is emergency contraception?

EC is most effective within the first 12-24 hours after unprotected sex. The sooner you start EC after unprotected sex, the better it will work. Depending on the brand of EC, it may be effective up for to 5 days (120 hours) after unprotected sex.

The efficacy is slightly decreased from 72-120 hours (3-5 days) after unprotected sex, but it is still recommended for use.

In terms of effectiveness, Levonorgestrel:

  • Is most effective for women with a body mass index (BMI) that is less than 25. To determine if this pertains to you, you can use a BMI calculator from Mayo Clinic.
  • Is most effective within 3 days (72 hours) after unprotected sex. It is less effective after 3 days.

Talk to your health care provider about which type of contraception is right for you.

What are the benefits of emergency contraception?

  • EC is an effective and safe back-up birth control method to prevent pregnancy after having unprotected sex.
  • EC is available at local pharmacies or health care clinics to anyone that is 17 years of age or older.
  • EC does not affect your ability to get pregnant later, if desired.

What are the downsides or health risks of emergency contraception?

  • EC will not provide protection from sexually transmitted infections (STIs).
  • EC is not intended for regular use and is not as effective as other forms of birth control. Talk to your health care provider about other long term options that may be right for you.

You may have some negative side effects while using EC. Nausea and vomiting are the most frequent side effects. If you are worried about feeling nauseous or vomiting, you can use anti-nausea medicine about one hour before taking the pill(s). You may also want to eat a snack or drink a glass of milk before taking the pills to reduce nausea.

Other side effects may include: breast tenderness, irregular bleeding, abdominal pain, fatigue, dizziness, or headaches.

Where can I get emergency contraception?

For ParaGard copper IUD:

  • Call UHS 734-764-8320, select option 2, and request “emergency contraception IUD”
  • Learn more about IUDs

By prescription (ella): Call UHS 734-764-8320, select option 2, and request “ella emergency contraception.” You can also get it in advance (you don’t have to wait for an emergency to get it).

Without prescription (Levonorgestrel): You can buy it at pharmacies, including the UHS Pharmacy, and other stores that sell medication. It can be purchased by both males and females of any age. There is no limit on the quantity that can be purchased at one time.

If you are under 17 years old, you need a prescription to get EC.

Important tips

  • Take EC as soon as possible! The sooner you start the EC after unprotected sex, the more effective it is.
  • If you do not regularly use another form of birth control, you can keep some EC at home in case of an emergency. This will allow you to take it as soon as possible after unprotected sex.
  • EC is a good backup birth control option. After you use the morning-after pill, talk with your health care provider to find the best type of birth control for you to use on a regular basis.
  • If you vomit within two hours after taking EC pills, call your health care provider.
  • After you take EC, it is normal for your next period to be different than usual. Your period may come earlier, be lighter or heavier, or you may have spotting throughout the month.
  • If you do not have a period in the next month after taking EC, take a pregnancy test and talk with your health care provider.

Personal Experiences

Resources on EC:

  • For questions, call for Nurse Advice.
  • Emergency Contraception website from the Office of Population Research at Princeton University and the Association of Reproductive Health Professionals
  • Planned Parenthood Emergency Contraception

Related resources from UHS:

  • Contraception
  • Pregnancy Testing
  • STI Assessment
  • HIV Antibody Testing
  • Resources for Sexual Health

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