TABLE 1. Facts About Levonorgestrel-Based Emergency Contraception

Characteristic	Fact
Dose and regimen	1.5 mg taken at one time, within 120 hours of unprotected sex, is the best approach.
Mechanism of action	Preventing/delaying/disrupting ovulation.
	Possibly thickening cervical mucus.
	Does not prevent implantation based on best evidence.
	Does not disrupt established pregnancy.
Effectiveness	52%–94% reduction in what risk of pregnancy would have been; better if taken sooner after unprotected sex.
Medical eligibility	Should not be taken if the woman has a confirmed pregnancy (because no need to take), although best evidence indicates it would not harm fetus.
Medical eligibility	Otherwise, no medical restrictions, including age.
Side effects	Minimal and not harmful (for example, possible mild nausea, menstrual changes).
Repeat use	Regular repeat use not recommended because of relatively poor effectiveness over time and possible side effects such as menstrual irregularity. However, repeat use poses no known health risks.