Emergency contraception is used to prevent pregnancy after unprotected sex but before pregnancy begins. Currently, women can use emergency contraception by taking higher doses of the active ingredients found in ordinary oral contraceptive pills [either combined estrogen-progestogen (progestin) or progestogen-only formulations], or by having providers insert copper-bearing intrauterine devices (IUDs). The antiprogestogen mifepristone also has an excellent efficacy and safety profile as emergency contraception, but it is currently available for this indication only in China. Many studies have documented providers' and women's fears about the individual and public health safety risks of emergency contraception. Some of these concerns include potentially increased risks of cardiovascular events (including arterial and venous disease), worries about possible effects on future fertility, feared teratogenic consequences following method failure or inadvertent use during pregnancy, exaggerated or extreme fears of adverse tolerability, and concerns about drug interactions with other medications. Wider public health questions include feared reductions in the use of ongoing, more effective contraception, possible 'abuse' of emergency contraception through overly frequent use, and potential increases in risky sexual encounters (owing to the existence of a back-up, postcoital method) and therefore in rates of sexually transmitted infections, including HIV/AIDS. These fears can each be generally allayed. Direct and indirect investigations of emergency contraception in the biomedical and social science literature, the extensively documented safety profile of ordinary oral contraceptives, and more than 30 years of clinical experience since hormonal emergency contraception was first described, give strong evidence for its safety. This review confirms declarations by the World Health Organization and the US Food and Drug Administration, and shows that emergency contraception has an excellent safety profile in nearly all women. Finally, emergency contraception allows women a second chance to avoid unwanted pregnancies. Whether pregnancy is carried to term or terminated, the condition has inherent risks that are greater than any posed by emergency contraception.