The Morning After Pill 


How it Works
How effective is it?
Risks and Side Effects
Who can’t take Emergency Contraception?
Emergency Contraception Options
How Emergency Contraception is prescribed
How to take Emergency Contraception
Important Notes
Emergency Contraception Hotline

Emergency contraception (EC) is the use of Plan B to prevent pregnancy after a contraceptive method has failed or because none was used.

How it Works:
If used within the first 72 hours after unprotected intercourse, EC probably works in one or more of the following ways:

  • Progestational hormones in the pills interfere with the sperms’ ability to travel up through the uterus and into the fallopian tube to fertilize the egg, or make it difficult for the egg to implant in the uterus.

How Effective is it?:
If used within the first 72 hours after unprotected intercourse, EC is greater than 90% effective.


  • Pregnancy prevention
  • Inexpensive
  • Relatively noninvasive


  • Cannot be used by women who cannot use birth control pills
  • Pregnancy may still occur
    • If a fertilized egg is already implanted in the uterus
    • If it is taken more than 72 hours after unprotected intercourse
    • Failure of emergency contraception
  • Best if used within 72 hours of unprotected intercourse

Side Effects:

  • Nausea and/or vomiting (take with food)
  • Breast tenderness
  • Irregular bleeding (period may be early or late)
  • Headache

Who can’t take Emergency Contraception?:

  • Hypersensitivity to any of the components of the drug
  • Unexplained bleeding from vagina
  • Already established pregnancy

Emergency Contraception Options:

  • Plan B (progestin only)

How Emergency Contraception is prescribed:

  • A pregnancy test is done
  • STD testing may be done if desired or recommended by the health care provider
  • A blood pressure check, heart rate, and temperature is usually done

How to take Emergency Contraception:

  1. Take one dose within 72 hours of unprotected intercourse (take about 20 minutes after eating)
  2. If you vomit within an hour after taking the emergency contraception, call your health care provider 
    (you will probably need to repeat the dose or the whole procedure)

Important Notes:

  • Emergency contraception should be used for just that- emergencies- and is not recommended for routine use.
  • If rape or sexual assault occurred, go to an emergency room for treatment.
  • Talk with your health care provider about methods of contraception you may be interested in for ongoing protection (some methods can be started immediately or the day after using EC).
  • If you have not started your period within 3 weeks after the EC, return to your health care provider.

Emergency Contraception Hotline
1-800-584-9911, 1-888-NOT-2-LATE

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