Possible Side Effects

Emergency contraception (EC), sometimes called “the morning-after pill,” has not been found to have any long-term or serious side effects. In most cases, women who take EC will experience no complications. However, some forms of EC will cause minor side effects, and rarely, EC can cause a more serious problem.

Emergency contraception that contains only the hormone progestin has been found to cause fewer side effects than EC pills that contain a combination of estrogen and progestin. Progestin-only EC pills include Plan B One-Step, My Way, Next Choice One Dose, and two-dose levonorgestrel tablets. Combination pills, which include most regular birth control pills, can be used as EC and are more likely to cause side effects. An intrauterine device (IUD) can also be used as EC, and it carries with it a set of side effects, too.

Possible side effects of emergency contraception

The most common side effects felt as a result of taking EC include: (2)

  • nausea and/or vomiting
  • headache
  • feeling tired
  • fatigue
  • feeling dizzy
  • lower abdominal pain
  • vaginal bleeding
  • breast tenderness

Most of these symptoms will resolve within two or three days of taking EC.

In addition to the above symptoms, women who choose to have an IUD inserted as EC may experience these additional side effects:

  • pelvic infection
  • damage to the uterus

Is vaginal bleeding normal after taking emergency contraception?

Some women who take EC may experience light vaginal bleeding. This will typically end within three days of taking the medicine. If it does not, or if the bleeding becomes heavier, contact your health care provider. The bleeding may be a sign of a more serious problem. (4)

Can you prevent side effects from emergency contraception?

If you’re worried about side effects or have a history of side effects when taking EC, talk with your health care provider about your concerns. He or she may prescribe additional medicine that can help you prevent or treat side effects, such as nausea, if they occur.

If you begin to experience dizziness or nausea after taking EC, it’s important you lie down and prevent vomiting as best you can. If you vomit within an hour of taking EC, you may need to take another dose. If you do get sick, call your health care provider or family planning clinic to find out if you should take an additional EC dose. (5)

Can emergency contraception affect my period?

Yes, EC can affect your menstrual cycle. Your next period may be as much as a week early or a week late. If your period is more than a week late, you may want to take a pregnancy test. (4)

When should I seek emergency medical care?

Light, unexpected vaginal bleeding is possible with EC use. However, some cases of unusual bleeding can be serious. If you are experiencing unexpected vaginal bleeding as well as abdominal pain and dizziness, call your health care provider. Also, if your bleeding does not end within three days or if it becomes heavier, call your health care provider. Your symptoms may be a sign of a more serious condition that requires medical treatment. 

Can I still get pregnant if I take emergency contraception?

EC prevents pregnancy; it does not end one if you are already pregnant.

EC is not 100% effective. The sooner you take EC, the more effective it will be at preventing an unplanned pregnancy. EC is most effective if taken within 72 hours (three days), but it can be taken up to five days after your unprotected sexual encounter and still prevent pregnancy. (2) According to the U.S. Department of Health and Human Services, 15 women out of 100 who use emergency contraception within 72 hours will become pregnant. One woman out of 100 will become pregnant if they opt for the IUD and have it put into place within five days. (2)

If you take EC and your next period is more than one week late, you may want to take a pregnancy test.