Hormonal emergency contraception

In the 1960s, high-dose estrogen was identified as a highly effective emergency contraceptive but was associated with a high frequency of nausea and vomiting. The combination of low-dose estrogen and a progestin (the Yuzpe regimen) is highly effective and much better tolerated. Recently, a progestin-only regimen containing levonorgestrel was found to be more effective than the Yuzpe regimen and caused significantly less nausea and vomiting. Danazol, an antigonadotropin, is well tolerated but has questionable efficacy. Mifepristone has several pharmacologic actions that make it highly effective with an adverse-effect profile similar to that of the Yuzpe regimen. Progress has been made in the last 3 years toward increasing the number of emergency contraceptives that are accessible to women in the United States, and several highly effective options are available. The most effective and well-tolerated regimen available is levonorgestrel. However, the barriers to access and low patient and provider awareness limit the impact of emergency contraception on the rate of unintended pregnancies.