Regimen Update: Timing and dosage of levonorgestrel-alone emergency contraceptive pills

2013
Publication type: EC Fact Sheets
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Levonorgestrel-alone emergency contraceptive pills (LNG ECPs) are available in over 140 countries. Two kinds of LNG ECP packages are available: one contains a single pill with a dosage of 1.5 mg, and the other contains two pills of 0.75 mg each.

The labels on both kinds of ECP packages say that the treatment should be started within 72 hours (3 days) after unprotected intercourse. The labels on two-pill ECP packages specify that the second pill should be taken 12 hours after the first. However, these labels do not reflect current scientific information.

Dosage: A WHO-led study in 10 countries established that a single dose of 1.5 mg LNG is as effective as two doses of 0.75 mg.1 Two Nigerian studies found similar results.2,3 Taking only one dose is simpler for women than taking two doses 12 hours apart.

Timing: Data suggest that LNG ECPs have some efficacy 4 days or even 5 days after sex.4,5 Some6 but not all4 studies have found that LNG ECPs may be more effective the sooner they are taken after sex.

Conclusions

  • Women should take LNG ECPs as a single dose of 1.5 mg. If using a package that contains two pills of 0.75 mg LNG, a woman should take both pills at the same time.
  • Women should take the 1.5 mg LNG ECP dose as soon as possible after sex, but the treatment may be used up to five days after the coital act.

References

1 von Hertzen H, Piaggio G, Ding J, Chen J, Song S, Bartfai G, et al. Low dose mifepristone and two regimens of levonorgestrel for emergency contraception: a WHO multicentre randomised trial. Lancet. 2002;360(9348):1803-10.

2 Arowojolu AO, Okewole IA, Adekunle AO. Comparative evaluation of the effectiveness and safety of two regimens of levonorgestrel for emergency contraception in Nigerians. Contraception. 2002;66(4):269-73.

3 Dada OA, Godfrey EM, Piaggio G, von Hertzen H. A randomized, double-blind, noninferiority study to compare two regimens of levonorgestrel for emergency contraception in Nigeria. Contraception. 2010;82(4):373-8.

4 Piaggio G, Kapp N, von Hertzen H. Effect on pregnancy rates of the delay in the administration of levonorgestrel for emergency contraception: a combined analysis of four WHO trials. Contraception. 2011;84(1):35-9.

5 Glasier A, Cameron ST, Blithe D, Scherrer B, Mathe H, Levy D, et al. Can we identify women at risk of pregnancy despite using emergency contraception? Data from randomized trials of ulipristal acetate and levonorgestrel. Contraception. 2011;84(4):363-7.

6 Creinin MD, Schlaff W, Archer DF, Wan L, Frezieres R, Thomas M, et al. Progesterone receptor modulator for emergency contraception: a randomized controlled trial. Obstetrics and Gynecology. 2006;108(5):1089-97.