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How Does Emergency Contraception Work?

If you think you need emergency contraception, you need answers fast. The good news is you have a lot of reliable options that can help if you act quickly. Learn more about your choices and how they work.

Understanding Emergency Contraception

Emergency contraception can help if you just had sex and something went wrong -- you forgot to use protection, you used it incorrectly, or the condom broke, for instance. It's also an important option for women who were forced to have sex. By using emergency contraception within 3 days of sex (the sooner, the better), you can dramatically lower your risk of getting pregnant. Though not as effective, it may also work up to 5 days after sex.

How It Works

Emergency contraception pills use hormones or medications that block pregnancy. Most use the same hormones that are in regular birth control pills.

Emergency contraception pills mainly work by stopping the release of an egg. The pills also may stop sperm from fertilizing the egg. They also may prevent a fertilized egg from implanting in the uterus. If you're already pregnant, most emergency contraception pills will have no effect.

Emergency contraception works well. But you should take it quickly -- preferably within 24 hours of sex. Yes, it's often called the "morning after" pill. But really, the sooner you take it, the more effective it will be. Studies show that if you take emergency contraception within 72 hours of sex, you have only a 1% to 2% chance of getting pregnant. Some types can still work up to 5 days after sex.

Types of Emergency Contraception

A number of methods are available: several kinds of pills, or an IUD.

Most emergency contraception pills use levonorgestrel, a form of the hormone progesterone. They include:

  • Plan B One-Step
  • Generic levonorgestrel, like My Way and Next Choice One Dose

You should use these drugs within 72 hours of having sex. They may still work up to 5 days later, but they're less effective with time. There are some differences among them. Plan B One-Step, My Way and Next Choice One Dose are one pill. Some other generics are two pills that you take at the same time.

Until recently, you had to be 17 or older to get Plan B One-Step without a prescription. However, the FDA removed the age restriction -- now people of any age should be able to buy Plan B One-Step without a prescription. If you're 17 or older, you can get generic levonorgestrel -- like My Way or Next Choice -- without a prescription. If you're under 17, you need a prescription.

Also, research shows that Plan B One-Step starts to lose its effectiveness in women heavier than 165 pounds and is not recommend for anyone over this weight. Instead, a copper-T IUD is the suggested option for emergency contraception in this group.

WebMD Medical Reference

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