The emergency pill should be taken as early as possible after unprotected sex. This is important because then the drug can delay ovulation earlier and thus has a higher chance in preventing the egg’s fertilisation. Depending on the respective active substance, the drug can be swallowed a maximum of 48 to 72 hours after unprotected intercourse.

However, if the pill is taken too late, or if fertilisation has already taken place and the egg has implanted in the uterus, the drug will not work. Should your period not start four weeks after using the emergency contraceptive pill, you should take a pregnancy test to rule out an unwanted pregnancy.