How soon after unprotected sex the pill should be taken to be effective is mainly related to the type of pill chosen. If you choose an emergency contraceptive pill with progestin and estrogen and progesterone as its main ingredients, it is effective if taken within 72 hours after unprotected sex. After taking one tablet, the patient needs to take another tablet 12 hours later, in which case the contraception is more effective and the chances of an unplanned pregnancy are around 2%. If you choose the emergency contraceptive pill with mifepristone as the main ingredient, it is more effective when used within 120 hours after unprotected sex and only needs to be taken once. However, emergency contraceptive pills are highly effective hormones that tend to disrupt the endocrine system, and they are also prone to contraceptive failure and should not be used as a regular method of contraception.