Emergency Contraception - Topic Overview
A doctor or other health professional has to insert an
How well does it work?
works very well. The sooner you use it, the more likely it is to prevent
- Emergency contraception, such as Plan B, can prevent an average of about 74% of pregnancies.1
- If a woman takes emergency contraception on the fourth or fifth day after unprotected sex, ulipristal (such as Ella) may work better than levonorgestrel (such as Plan B).2
- The copper IUD is more than 99% effective. Only about 2 women out of 1,000 who use it for emergency contraception will get pregnant.3
If you haven't started your period within 3 weeks after
using emergency contraception, get a pregnancy test.
Does it cause side effects?
contraception may cause some side effects.
- Emergency contraception may cause spotting or mild symptoms
like those of birth control pills. It usually doesn't cause nausea.
- Birth control pills can cause nausea or vomiting. In some women,
they can also cause sore breasts, fatigue, headache, belly pain, or dizziness.
- An IUD may cause cramping and bleeding during the first few days
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.
What else should you think about?
- Emergency contraception pills won't protect
you for the rest of your cycle. Use your regular method of birth control, or
- If you are overweight or obese, emergency contraception pills may
not work as well to prevent a pregnancy. Talk with your doctor about methods of emergency
contraception that aren't affected by a woman's weight, such as the copper IUD.
- Unless you get an IUD, emergency contraception does
not take the place of regular birth control. Find a good method of birth
control you can use every time you have sex.
contraception does not prevent sexually transmitted infections (STIs). If you are
worried you might have been exposed to an STI, talk to your
- Accidents can happen. It is a good idea to keep a set of
the pills on hand in case you ever need it.