What Is It?

Emergency contraception is a way to prevent pregnancy after unprotected sex. Often called the morning-after pill, emergency contraception pills (ECPs) are hormone pills that women can take after having sex. There are different types of ECPs. One type, levonorgestrel (brand names: Plan B and Next Choice), has been on the market for a while. It works up to 72 hours after having unprotected sex.

The other type, ulipristal acetate (brand name: ella), was recently approved for use in the United States and can be taken up to 5 days after unprotected intercourse.

Levonorgestrel ECPs are often available without a prescription to those 17 years and older. Prescriptions are required for those 16 and under, as well as for ulipristal.

The intrauterine device (IUD) can sometimes be used as a form of emergency contraception. This is rarely prescribed for teens, though.

How Does It Work?

Levonorgestrel works by giving high doses of a progesterone-like hormone to prevent pregnancy. The number of pills taken depends on the type of pill being used. The first dose of pills should be taken as soon as possible within 72 hours of unprotected intercourse, sometimes followed by a second dose of pills 12 hours later. This type of ECP is most effective when it is taken as soon as possible after intercourse, although some studies have shown that it can still work up to 120 hours after intercourse.

The hormone may work in a number of ways to prevent pregnancy. It may delay ovulation (the release of an egg during a girl's monthly cycle), affect the development of the uterine lining, and disrupt the actual fertilization process. If implantation has already occurred and a girl is pregnant, levonorgestrel will not interrupt the pregnancy.

The newer type of ECP, ulipristal acetate, is a different type of medication. It delays ovulation and may help prevent implantation. This type stays effective up to 5 days after unprotected intercourse.

Emergency contraception will not prevent pregnancy if a girl has unprotected sex after taking the ECPs.

How Well Does It Work?

About 1 or 2 in every 100 women who use ECPs will become pregnant despite taking ECPs within the recommended amount of time. The effectiveness of emergency contraception methods is calculated differently from the effectiveness of other contraceptives because of how they are used. Emergency contraception is the only type of contraception method that is used after unprotected sex.

Because emergency contraception does not prevent all pregnancies, a woman should see her doctor if she doesn't get her next expected period after taking it.

Protection Against STDs

Emergency contraception does not protect against sexually transmitted diseases (STDs). Couples having sex must always use condoms to protect against STDs even when using another method of birth control. If a condom breaks (or a couple has unprotected sex), it's a good idea to get tested for STDs.

Abstinence (not having sex) is the only method that always prevents pregnancy and STDs. If a girl has been forced to have unwanted sex, she should see a doctor right away to be tested for STDs. That's because it's important to treat some STDs immediately before they develop into bigger problems.

Possible Side Effects

Many girls who take emergency contraception pills experience side effects such as nausea, vomiting, breast tenderness, abdominal pain, headache, dizziness, and fatigue. Such side effects are usually minor, and most improve within 1 to 2 days. A girl's menstrual period may be temporarily irregular after taking ECPs.

Who Uses It?

Emergency contraception is not recommended as a regular birth control method. Instead, it is used for emergencies only. If a couple is having sex and the condom breaks or slips off, if a diaphragm or cervical cap slips out of place, or if a girl forgot to take her birth control pills for 2 days in a row, a girl may want to consider using emergency contraception. It is also available to teens who are forced to have unprotected sex.

Emergency contraception is not recommended for girls who know they are pregnant.

How Do You Get It?

In most cases, teens need to get ECPs through a doctor, nurse practitioner, or a health clinic. Sometimes pharmacists can sell levonorgestrel over the counter (without a prescription) to people over 17, with proof of age. However, since laws change all the time and only some pharmacists are able to do this, call your pharmacy to find out if it is possible to get ECPs without a prescription.

ECPs need to be used as soon as possible after having unprotected sex. To find out who can provide or prescribe ECPs in your area, visit the The Association of Reproductive Health Professionals website at www.not-2-late.com. [Please note: By clicking on this link, you will be leaving this site.]

How Much Does It Cost?

Depending on the types of pills, the emergency contraception pill costs between $10 and $80. Many health insurance plans cover the cost of emergency contraception and family planning clinics (such as Planned Parenthood) may charge much less.

Reviewed by: Larissa Hirsch, MD
Date reviewed: February 2011