Emergency Contraception

Emergency contraception is available to prevent pregnancy:

After sexual assault
After consensual intercourse in which contraception is not used
When contraception is used but fails (for instance, when a condom breaks or a diaphragm dislodges)
Basics of Emergency Contraception

Emergency contraception, also called the “morning after pill,” uses the hormones found in birth control pills to prevent either fertilization or the implantation of a fertilized egg in the uterine lining. It is not the same thing as the "abortion pill" [See Mifepristone, below]. Emergency contraception is usually given as hormone pills within 72 hours of unprotected sex. Some of these pills (such as Plan B) contain only progestin. Other pills (such as Preven) contain a combination of estrogen and progestin. Emergency contraception is also sometimes prescribed as an intrauterine device (IUD), which is inserted within 5 days of unprotected sex.

In 2006, after a long political battle, the FDA approved the Plan B brand as the first over-the-counter emergency contraception. It is available without a prescription at pharmacies and health clinics for women over age 18. Women will need to present proof of age to purchase it. Girls younger than age 18 will still need to get a prescription from their doctors.

Specific Methods
Emergency Oral Contraception. There are two forms of emergency oral contraception:

The Yuzpe method uses two doses of combined oral contraceptives containing estrogen and the progestin levonorgestrel. In the U.S., Preven is the standard brand used for the Yuzpe method. In general, this approach is effective in preventing pregnancies 75% of the time (although some studies report lower success rates).
The other standard approach uses two doses of the progestin levonorgestrel, which includes Plan B. Studies indicate that this method causes less stomach distress and is more effective than the Yuzpe method. In one large study, levonorgestrel prevented pregnancy in 85% of women requiring emergency contraception.
With both methods, the woman takes her first pill or pills within 72 hours of intercourse and a second dose 12 hours later. The earlier they are taken, the more effective they are in preventing pregnancy. Some evidence suggests they may be effective up to 5 days after sex, although effectiveness is greater if used within 72 hours. Although these regimens are popularly called morning-after pills, they are actually the same oral contraceptives that users of OCs take regularly.

Side effects of emergency oral contraception methods include:

Nausea and vomiting are common in both approaches, but particularly with Preven.
Fatigue
Headaches
Dizziness
Diarrhea
Breast tenderness
Fluid retention
Changes in the timing or flow of the woman's next menstrual period. A 2006 study found that emergency contraceptive pills (such as Plan B) that contain levonorgestrel may alter the menstrual cycle and the length of periods.
Immediate side effects typically subside within 1 - 2 days of taking the second dose. Family planning experts warn that emergency pill use should not be treated as a substitute for regular contraception.

Copper-Releasing IUD. An alternative emergency contraception relies on insertion of a copper-releasing IUD within 6 days of intercourse. It can be removed after the woman's next period, or left in place to provide ongoing contraception. The copper IUD reduces the risk of pregnancy by 99.9%.

Mifepristone. Mifepristone is the drug used in Mifeprex (formerly called RU 486). This "abortion pill" blocks progesterone action so that the lining thins and deters implantation of the egg. Unlike emergency oral contraception, the combination of mifepristone and misoprostol can abort an existing pregnancy. A single dose of mifepristone used within 72 hours of unprotected sex can prevent pregnancy.

When used after pregnancy occurs, mifepristone is taken within 49 days of a woman's last period. The woman is given three pills containing mifepristone during her first doctor's visit, and then a second drug (misoprostol) 2 days later. Misoprostol causes uterine contractions that will expel the embryo. A third visit is needed to ensure the abortion is successful. Women who have ectopic or tubal pregnancies cannot take mifepristone. Side effects include pain, and use of the pills may also cause nausea and bleeding.

There have been four reported deaths from infection (sepsis) in women who took mifepristone and misoprostol for medical abortion. In 2005, the manufacturer of Mifeprex revised the drug's prescribing label. The new information advises women to immediately contact their doctors or go to an emergency room if they experience abdominal pain or discomfort, or general malaise (weakness, nausea, vomiting, or diarrhea), with or without fever, more than 24 hours after taking misoprostol.