Cochrane for Clinicians

Putting Evidence into Practice

Emergency Contraception: Safety and Effectiveness


Am Fam Physician. 2020 Jun 1;101(11):651-652.

Author disclosure: No relevant financial affiliations.

Clinical Question

Which form of emergency contraception is the safest and most effective for preventing pregnancy after a single episode of unprotected intercourse?

Evidence-Based Answer

Oral mifepristone (Mifeprex), ulipristal (Ella), levonorgestrel-releasing emergency contraception (Plan B One-Step), ethinyl estradiol/levonorgestrel, and the copper intrauterine device (IUD; Paragard) are safe and effective for emergency contraception. 1 (Strength of Recommendation [SOR]: B, based on inconsistent or limited-quality patient-oriented evidence.)

In head-to-head comparisons, a one-time dose of mifepristone is more effective than any dose of oral levonorgestrel, with moderate-dose mifepristone (25 to 50 mg) being more effective than low-dose mifepristone (less than 25 mg; relative risk [RR] = 0.61). (SOR: B, based on inconsistent or limited-quality patient-oriented evidence.) All other forms of emergency contraception are more effective than ethinyl estradiol/levonorgestrel (RR = 0.57). (SOR: A, based on consistent, good-quality patient-oriented evidence.) Ulipristal is more effective than oral levonorgestrel alone (RR = 0.59). (SOR: A, based on consistent, good-quality patient-oriented evidence.)

The copper IUD is not inferior to any dose of mifepristone, but no direct comparison has been made between the copper IUD and other types of emergency contraception. (SOR: C, based on consensus, disease-oriented evidence, usual practice, expert opinion, or case series.) Adverse effects most often include nausea and vomiting for oral medications and abdominal pain and menorrhagia for the copper IUD.1

Practice Pointers

Emergency contraception is the use of a medication or device to prevent pregnancy following unprotected intercourse. Although the likelihood of pregnancy after a single episode of unprotected intercourse is highly variable depending on timing and other factors, emergency contraception can be more than 95% effective at preventing pregnancy when used within five days of in

Author disclosure: No relevant financial affiliations.


show all references

1. Shen J, Che Y, Showell E, et al. Interventions for emergency contraception. Cochrane Database Syst Rev. 2019;(1):CD001324....

2. Finer LB, Zolna MR. Declines in unintended pregnancy in the United States, 2008–2011. N Engl J Med. 2016;374(9):843–852.

3. American College of Obstetricians and Gynecologists. Emergency contraception. ACOG practice bulletin no. 152. Obstet Gynecol. 2015;126(3):e1–e11.

4. Hubacher D, Chen PL, Park S. Side effects from the copper IUD: do they decrease over time? Contraception. 2009;79(5):356–362.

These are summaries of reviews from the Cochrane Library.

This series is coordinated by Corey D. Fogleman, MD, assistant medical editor.

A collection of Cochrane for Clinicians published in AFP is available at



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