Morning after pill
Originally Published: December 21, 1995 - Last Updated / Reviewed On: June 1, 2009
How long after having had sex is the taking of the morning after pill useful?
Also known as emergency contraception, the "morning after pill" is a high dose of birth control pills taken within 120 hours (or five days) after unprotected intercourse to prevent pregnancy. But note: The sooner it is taken, the more effective it is. Emergency contraception (EC) is not to be confused with RU-486 (mifepristone), a pill that causes medical/chemical abortion in pregnant women within 49 days from the first day of their last menstrual period.
There are two forms of EC, and they may work in several ways: by delaying or inhibiting release of an egg (ovulation), preventing the egg and the sperm from meeting (fertilization), or keeping a fertilized egg from attaching to the uterine wall (implantation). If started within 72 hours of unprotected intercourse, progestin-only EC is more effective (89% efficacy) than combined hormonal pills that contain estrogen and progestin (75% efficacy). Users are also less likely to have nausea and vomiting from taking progestin-only EC than from the combined regimen. The most common form of EC is called Plan B, and it contains progestin as its only hormonal ingredient.
It's normal for some women to have irregular periods or unexpected bleeding after using EC. Women who don't get their periods within three weeks should visit a health care provider. Temporary side effects of using EC may include:
- stomach pains
- breast tenderness
- weight gain or loss
Plan B is available from pharmacists over-the-counter to women and men 17 and older. Because it's important to take EC as soon as possible after unprotected sex, this is a critical advance. If you're 17 or older, you might want to think about buying a package to have on hand, just in case. If you're under 17, you can ask your health care provider for a prescription before you need EC to avoid having to wait for an appointment. It's important to note, however, that EC is not intended to be used as a regular form of birth control. Columbia students under 17 can obtain prescriptions for emergency contraception by making an appointment with Primary Care Medical Services at x4-2284 or contacting the clinician-on-call (nights/weekends) at x4-9797.
For more information on EC, check out Health Services: Emergency Contraception or call the EC phone hotline at 1.888.NOT.2.LATE (1.888.668.2.5283). You can also find information in English, Spanish, French, and Arabic at NOT-2-LATE.com.
Knowing that you have options if, for any reason, you have unprotected intercourse can provide a tremendous sense of security. If you missed the 120-hour window, you can take a pregnancy test. If you're pregnant, talking about your options with a health care provider may help you decide what to do next.