The emergency contraceptive pill can be effective within 72 hours after sex, but it is not 100% effective and may fail. If you do not get your period when you should, it is recommended that you go to the hospital for a blood HCG test to see if there is a possibility of pregnancy. Emergency contraceptive pills are not recommended for women to take regularly because they may cause endocrine disorders in women and may even cause symptoms such as continuous bleeding during menstruation. If a woman does not want to have children, she can use intrauterine device or condom for contraception.