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Research Summaries

All Research Summaries

Is Emergency Contraception (EC) Safe?

Original article by: Weiss DC, Harper CC, Speidel JJ, Raine TR. Bixby Center for Global Reproductive Health, University of California, San Francisco. Available at:


This research brief from the Bixby Center for Global Reproductive Health compiles and summarizes research on the safety of EC in scientific, concise, clear, and user-friendly terms. It includes information about hormones found in various types of EC. It also discusses "absolute risk" (potential negative health consequences of taking the drug, such as side effects or addictiveness) and "risk-benefit" (the risks of not taking the drug against the benefits of taking it.) The brief states that EC poses minimal absolute risks, particularly when compared to its major potential benefit of preventing unintended pregnancy.

Highlights: EC is a safe way to prevent unintended pregnancy

The hormones found in EC and birth control pills have been used safely by tens of millions of women worldwide for decades. EC has a particularly high safety profile, with ample research documenting that:

  • EC is non-toxic, with only short-term, non-serious side effects. Side effects generally last one or two days after taking the pills and are substantially lower with Plan B® than with the combined hormonal method used in most birth control pills.

  • EC poses no risk of addiction or overdose; even when used repeatedly, no severe health consequences result. Even among women who have used EC up to seven times in one menstrual cycle, no serious outcomes occurred and side effects were limited to those that could result after a single use. Conversely, hundreds of deaths occur in the U.S. each year from overdoses of aspirin or other over-the-counter medications.

  • There are no major drug interactions or medical complications associated with EC. The product labeling for Plan B® (levonorgestrel) EC lists only three contraindications: (1) allergy to any components of the product, (2) undiagnosed abnormal genital bleeding, or (3) known or suspected pregnancy — not because EC is unsafe in this circumstance, but because it will not work.

  • Use of EC does not increase the risk of ectopic pregnancy, nor does it compromise an existing pregnancy or future fertility. In fact, EC lowers the absolute risk of ectopic pregnancy by preventing pregnancy in general.

  • EC does not cause birth defects. If EC fails to prevent pregnancy, or a woman takes EC when she is already pregnant, there will be no harm to her, the pregnancy, or the fetus. Among 6,000 women participating in EC safety and efficacy studies to date, there have been no negative birth outcomes attributable to EC.

  • EC is safe even for women who should not use long-term hormonal contraception such as birth control pills. Health risks from hormonal contraception, such as blood clots and stroke, are related to estrogen. Because Plan B® is a progestin-only product, it does not involve such risks. In fact, both progestin-only birth control pills and Plan B® are safe for women who cannot use combined hormonal contraception, including women who are diabetic, have high blood pressure, or are at risk for blood clots or heart disease. Additionally, EC is intended for one-time use, in contrast to birth control pills, which are used daily on a continual basis. Thus, the total hormone dose for EC is much lower than that of the pill.

  • Use of EC does not affect a woman's ability to become pregnant in the future, as is the case for all rapidly reversible or non-injectable methods of hormonal contraception.

The potential consequences of unintended pregnancy far outweigh EC's risks: The scientific evidence is clear: EC is safe by all standards. In fact, more than 60 health and medical groups have declared that EC is "safer than aspirin." While EC's risks are negligible, its major potential benefit — prevention of unintended pregnancy — is substantial. In fact, for all women, the potential complications associated with pregnancy may be far more dangerous than short-term use of EC.