In the United States (US), access to emergency contraceptive pills (ECPs) expanded to nationwide in 2006 when regulators allowed Plan B, a brand of emergency contraception, to be sold without prescription. Using data from the National Health and Nutrition Examination Survey from 2001 to 2010. I examined any association between increased access to these ECPs in the US and negative consequences. I found an association between increased access to ECPs and a 2.2 per cent higher probability of any sexual activity, a 5.1 per cent increase in the likelihood of reporting sex with multiple partners, an increase in the average number of partners by 0.35, and a -7.6 per cent decrease in the likelihood of injectable contraceptive use. These results suggest that policies in the US and other countries that expand access to ECPs should be paired with information on ECPs' lack of protection against sexually transmitted infections and relatively lower efficacy compared to other forms of contraception.