Morning-after pills can help prevent pregnancy if you've had unprotected sex — whether you didn't use birth control, you missed a birth control pill or your method of birth control failed.
Morning-after pills can prevent pregnancy because conception typically doesn't occur immediately after sex. Instead, it may happen up to several days later. During the time between sex and conception, sperm travel through the fallopian tubes until they potentially reach an egg. As a result, using emergency contraception soon after unprotected sex isn't too late to prevent pregnancy.
Morning-after pills do not end a pregnancy that has implanted. Depending on where you are in your menstrual cycle, morning-after pills may act by one or more of the following actions: delaying or preventing ovulation, blocking fertilization, or keeping a fertilized egg from implanting in the uterus. However, recent evidence strongly suggests that Plan B One-Step and Next Choice do not inhibit implantation. It's not clear if the same is true for Ella.
Keep in mind that the morning-after pill isn't the same as mifepristone (Mifeprex), also known as RU-486 or the abortion pill. Mifeprex terminates an established pregnancy — one in which the fertilized egg has attached to the uterine wall and has already begun to develop.
Emergency contraception is an effective option for preventing pregnancy after unprotected sex, but it isn't as effective as other methods of contraception and isn't recommended for routine use. The morning-after pill also doesn't offer protection from sexually transmitted infections.
An estimated 1 to 2 women will become pregnant out of 100 women who have unprotected sex one time and correctly use the morning-after pill.
The morning-after pill isn't appropriate for everyone. Tell your health care provider if:
- You're allergic to any component of the morning-after pill
- You're taking certain medications that may decrease the effectiveness of the morning-after pill, such as barbiturates or St. John's wort
- You're breast-feeding (Plan B One-Step and Next Choice can be used during breast-feeding, but Ella isn't recommended)
In addition, make sure you're not pregnant before using Ella. The effects of Ella on a developing baby are unknown. However, if you're already pregnant when you take Plan B One-Step or Next Choice, the treatment will simply be ineffective and won't harm the developing baby.
Side effects of the morning-after pill typically last only a few days and may include:
- Nausea or vomiting
- Breast tenderness
- Bleeding between periods or heavier menstrual bleeding
- Lower abdominal pain or cramps
For maximum effectiveness, emergency contraception should be started as soon as possible after unprotected intercourse, and within 120 hours. You can take emergency contraceptive pills anytime during your menstrual cycle.
If you're age 17 or older, Plan B One-Step and Next Choice are available over-the-counter at most pharmacies. If you're age 16 or younger or you want to use Ella, you'll need a prescription from your health care provider. Some health care providers may provide an advance prescription for emergency contraception, just in case.
Remember to talk to your health care provider about any other medications you're taking.
To use the morning-after pill:
- Follow the morning-after pill's instructions. If you use Next Choice, take one Next Choice pill as soon as possible and less than 72 hours after unprotected sex. Take the second Next Choice pill 12 hours later. If you use Plan B One-Step, take one Plan B One-Step pill as soon as possible and less than 72 hours after unprotected sex. If you use Ella, take one Ella pill as soon as possible and less than 120 hours after unprotected sex. Consider taking a pain reliever, such as ibuprofen (Advil, Motrin, others), at the same time.
- If you vomit within two hours after taking the morning-after pill, contact your health care provider to discuss whether to repeat the dose.
- Don't have sex until you start another method of birth control. The morning-after pill doesn't offer lasting protection from pregnancy. If you have unprotected sex in the days and weeks after taking the morning-after pill, you're at risk of becoming pregnant. Be sure to begin using or resume use of birth control.
Using the morning-after pill may delay your period by up to one week. If your period is more than one week late, take a pregnancy test.
If you have bleeding or spotting that lasts longer than a week or develop severe lower abdominal pain three to five weeks after taking the morning-after pill, contact your health care provider. These may be signs or symptoms of a miscarriage or an ectopic pregnancy — when the fertilized egg implants outside the uterus, usually in a fallopian tube.