AdvertisementEmergency contraception: How it works, how effective it is and how to get itJuly 08, 2022Maria GodoyCarmel WrothfacebookEmailPlan B is one brand of the emergency contraceptive levonorgestrel, which works by delaying ovulation. It is sold over the counter at pharmacies, but is often kept in locked boxes or is only accessible by asking a pharmacist. (Getty Images)