Effectiveness in Preventing Pregnancy
- There are two main types of emergency contraception: Emergency contraceptive pills (ECPs) and copper T intrauterine device (IUD). Effectiveness varies by method.
What is emergency contraception?
Emergency contraception is birth control that you use after you have had unprotected sex—if you did not use birth control or your regular birth control failed. Emergency contraception should be used as soon as possible within three to five days after unprotected sex to prevent pregnancy. ECPs are more effective the sooner you take them. Emergency contraception does not work if you are already pregnant.
There are two main types of emergency contraception: ECPs and copper T IUD.
How do I use it?
Progestin only: Research has shown that the pills containing levonorgestrel are effective when taken within the first three days after unprotected sex and are ineffective thereafter. The ulipristal acetate pill is the most effective oral emergency contraceptive when taken within the first five days after unprotected sex.
- Levonorgestrel (Plan B One-Step, Next Choice One Dose, After Pill, Take Action,and My Way): Progestin-only pills consist of one pill that the instructions state must be taken within three days (72 hours).
- Ulipristal acetate (ella): Pills consists of one pill that must be taken within five days (120 hours).
Combined regimen: The combined regimen consists of two doses of estrogen and progestin pills. The first combined dose must be taken within three days (72 hours), and a second combined dose must be taken 12 hours later.
Copper T IUD
A copper T IUD is inserted within five days (120 hours) after unprotected sex.
- Copper T IUD is a T-shaped device that is placed in the uterus by a healthcare provider.
How effective is it?
- Levonorgestrel: About 87 out of 100 women who would have become pregnant will not become pregnant after taking these pills.
- Ulipristal acetate: Six or seven out of every 100 women who would have become pregnant will not become pregnant after taking ulipristal acetate.
- Estrogen and progestin: About 75 out of 100 women who would have become pregnant will not become pregnant after taking this combined regimen of pills.
Copper T IUD
- The copper T IUD is the most effective emergency contraceptive method. Out of 1,000 women who use this method, only one will become pregnant.
How do I get emergency contraception?
ECPs are available at some pharmacies. Women and men of all ages can get emergency contraceptive pills, other than ulipristal acetate, without a prescription. Check that your local pharmacy carries ECPs before making a trip there.
Women of all ages need a prescription for ulipristal acetate. Contact your healthcare provider to get a prescription. Even if you do not need emergency contraception today, you may want to ask your provider for a prescription so that you have it in case you need it in the future.
Many family planning clinics dispense emergency contraceptive pills and offer IUDs as a birth control option.
Advantages of emergency contraception
- Emergency contraception is safe and effective in preventing pregnancy after unprotected sex.
- Some emergency contraception is available over the counter.
- Emergency contraception is private. It is your choice if your partner knows about it.
- The copper T IUD can remain in place for up to 10 years as a woman’s regular contraception.
Drawbacks of emergency contraception
- ECPs are not as effective as some other types of birth control.
- ECPs require a clinic visit and a prescription in some cases.
- ECPs may cause side effects, including nausea (anti-nausea medication might help with this), vomiting, stomach pain, and headaches.
- Emergency contraception does not work if you are already pregnant. Women who are pregnant or suspect they are pregnant should not use emergency contraception.
- Emergency contraception does not protect against sexually transmitted diseases (STDs), including HIV. Always use a condom to reduce the risk of STDs.
- Birth Control: Medicines To Help You
- Emergency Contraception
- United States Selected Practice Recommendations for Contraceptive Use, 2016
- Cleland, K., Zhu, H., Goldstuck, N., Cheng, L., & Trussell, J. (2012). The efficacy of intrauterine devices for emergency contraception: A systematic review of 35 years of experience. Human Reproduction, 2012 Jul 27(7), 1994–2000.
Did You Know? (Emergency Contraception)
Content last reviewed on May 21, 2019