Birth Control: Contraceptive Measures after Unprotected Sex

  • Medical Author:
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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What is the dosage, and what types of the morning after pill are available?

The most common type of emergency hormonal contraception involves the administration of the progesterone hormone levonorgestrel in two doses (marketed as Plan B in the U.S.).

Another formulation for emergency hormonal contraception uses estrogen along with levonorgestrel, but levonorgestrel-only medication may be more effective and causes less nausea compared to estrogen-containing products.

Clinical trials using low doses of mifepristone (known earlier as RU-486, sometimes called "the abortion pill") have shown that this agent is extremely effective as an emergency contraceptive when taken prior to ovulation, but it has not been approved for this use in the US. Mifepristone (Mifeprex) has been approved, in much higher doses, for terminating a pregnancy of less than 49 days' duration and must be taken under a physician's supervision.

Another type of anti-progestin medication that is similar to mifepristone in its structure and actions is known as ulipristal acetate. Ulipristal acetate (Ella) is marketed for emergency contraception in Europe and was approved by the US FDA in August 2010 for use in the US for emergency contraception up to 120 hours after intercourse. It is available by prescription only.

How effective is the morning after pill?

Although effectiveness of the oral contraceptives are dependent to some extent upon how soon after unprotected intercourse they are taken, efficacy studies have generally reported pregnancy rates of 0.2% to 3% with use of oral emergency contraception.

Does the morning after pill protect against STDS?

Emergency contraceptive pills do not protect women from sexually transmitted diseases (STDs).

Can the morning after pill be used as a primary form of birth control?

Emergency hormonal contraception or the morning after pill is not meant to be a primary birth control method. Once the emergency is over, a woman should receive proper counseling so that she can select an effective and appropriate contraceptive method to use on a regular basis if she continues to be sexually active.

Medically Reviewed by a Doctor on 2/18/2015

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