Important Notes: Emergency contraception (the morning-after pill) may prevent pregnancy for three days (72 hours) and sometimes five days (120 hours) after unprotected sex. Take emergency contraception as soon as possible after unprotected sex. If you don't have access to dedicated emergency contraception, oral contraceptives can be used as replacement it, but remember the following: 1) Only some contraceptives work as emergency contraception. 2) Different contraceptives require different dosages and time schedules to work as emergency contraception. 3) You must only use the first 21 pills in 28-day packs. 4) Birth control pills may be less effective than dedicated emergency contraception. For general information on emergency contraception, click here and here.