contraception is a way to prevent pregnancy if:
If you had sex without birth control, there is a chance
that you could get pregnant. This is true even if you have not started having
periods yet or you are getting close to
menopause. You could also get pregnant if you used a
birth control method that is not very reliable or if you didn't use it the
Using emergency contraception right away can prevent an
unwanted pregnancy and keep you from worrying while you wait for your next
period to start.
There are two main types of emergency contraception: pills and the copper
intrauterine device (IUD). Most women choose pills
because they work well, don't cost a lot, and are usually easy to get. The IUD
works very well, but it has to be inserted by a doctor.
Emergency contraception pills
work by preventing ovulation, fertilization, or implantation.
Emergency contraception hormones may prevent fertilization by stopping
the ovary from releasing an egg (ovum). They also make the fallopian tubes less
likely to move an egg toward the uterus. Emergency contraception is also
thought to thin the lining of the uterus, or
endometrium. The thickened endometrium is where a
fertilized egg would normally implant and grow.
The copper IUD for emergency contraception may work by killing sperm, preventing fertilization, or preventing implantation.
Emergency contraception. You can buy emergency contraception, such as Plan B or Next Choice, in most drugstores.
Some types of emergency contraception, such as ulipristal (for example, Ella) are available only with a prescription from a doctor.
Birth control pills. If you
already have birth control pills on hand, you may be able to use them for
emergency birth control. To find out which brands of pills work and how to take
them, go to:
Some pharmacists will not sell emergency contraception or fill
prescriptions for birth control pills. If this happens to you, ask for the
location of a pharmacist who will, or go to:
IUD. You can get an IUD from many
doctors, from college and public health clinics, or in most hospital emergency
rooms. An IUD has to be inserted by a doctor or other health
Emergency contraception pills
The pills come in 1-pill or 2-pill packages. Follow the directions in the package or take them as your doctor directs you to.
You can take emergency contraception up to 5 days after
unprotected sex. But it works best if you take it right away.
Birth control pills as emergency contraception
For most regular birth control pills, you take one dose
of 2 to 5 pills as soon as you can. Then you take a second dose 12 hours later.
The dose depends on the type of pill.
If you use birth control pills for emergency contraception,
keep the following in mind:
A doctor or other health professional has to insert an
works very well. The sooner you use it, the more likely it is to prevent
If you haven't started your period within 3 weeks after
using emergency contraception, get a pregnancy test.
contraception may cause some side effects.
Call your doctor if you have a headache, dizziness, or
belly pain that is severe or that lasts longer than 1 week.
are already pregnant, most pills won't harm the fetus. But some pills, such as ulipristal, may cause problems with the pregnancy. More research is needed to know for sure. An IUD could cause problems
with the pregnancy.
This Web site provides information about emergency
contraception. This includes the correct use, effectiveness, and expected side
effects of emergency contraception, along with how regular contraceptive pills
can be used for emergency contraception. The Web site is operated by the Office
of Population Research at Princeton University and by the Association of
Reproductive Health Professionals.
A searchable database of
emergency contraceptive providers in the United States is also
This site offers resources for emergency contraception,
including birth control pills available for this use and their side effects,
the use of an intrauterine device (IUD), and a fact sheet.
Information on this site is also provided in Spanish.
CitationsAmerican College of Obstetricians and Gynecologists (2010). Emergency contraception. ACOG Practice Bulletin No. 112. Obstetrics and Gynecology, 115(5): 1100–1109.Glasier AF, et al. (2010) Ulipristal acetate versus levonorgestrel for emergency contraception: A randomised non-inferiority trial and meta-analysis. Lancet, 375(9714): 555–562.Stewart F, et al. (2007). Emergency contraception. In RA Hatcher et al., eds., Contraceptive Technology, 19th ed., pp. 87–112. New York: Ardent Media.Other Works ConsultedAmerican Academy of Pediatrics (2005). Policy
statement: Emergency contraception. Pediatrics, 116(4):
1026–1035.American College of Obstetricians and Gynecologists (2010). Emergency contraception. ACOG Practice Bulletin No. 112. Obstetrics and Gynecology, 115(5): 1100–1109.Stewart F, et al. (2007). Emergency contraception. In RA Hatcher et al., eds., Contraceptive Technology, 19th ed., pp. 87–112. New York: Ardent Media.
May 4, 2012
Sarah Marshall, MD - Family Medicine & Femi Olatunbosun, MB, FRCSC - Obstetrics and Gynecology
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