Birth Control Options for Women - Emergency Contraception

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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.

Review Date: 10/22/2006
Reviewed By: Harvey Simon, M.D., Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.