Emergency birth control can prevent pregnancy if it is used within 3 days after you had unprotected sex. If you are already pregnant, emergency birth control will NOT stop the pregnancy. You may decide that you need emergency birth control if:
The 2 main forms of emergency birth control are:
Emergency birth control pills are also called morning-after pills. The pills contain female hormone. They may work in several ways to prevent pregnancy, such as:
Emergency birth control pills should be taken as soon as possible after unprotected sex. Depending on the type of medicine in the pills, the pills need to be taken no later than 72 to 120 hours (3 to 5 days) after you had sex.
Most women do not get pregnant if they take the pills within 3 days after sex. The effectiveness is highest (98%) if the pills are taken within 12 hours after sex. This means that no more than 2 women of every 100 get pregnant after taking the pills.
A copper intrauterine device (IUD) may be put into the uterus after unprotected sex. It may prevent pregnancy by:
A copper IUD is over 99% effective if the IUD is inserted within 5 days of unprotected sex. The IUD may then be left in the uterus as a regular method of birth control.
With either method of emergency birth control, you will usually have your next menstrual period at the expected time or within a week of the expected time.
If you have any questions, ask your healthcare provider or pharmacist for more information. Be sure to keep all appointments for provider visits or tests.