Hi, Thanks for posting in HCM. I understnad your concern. Unwanted 72 is an emergency contraceptive pill. It needs to be taken within 72 hours of having unprotected intercourse to prevent unwanted or accidental pregnancy. It does not necessitate to take another pill if intercourse is performed by 12 to 24 hours after the pill has been taken. It is advised to use other modes of contraception like condoms and spermicides or abstain from sexual intercourse until the withdrawal bleed takes place. The pill would prevent pregnancy by causing withdrawal bleeding within 3 weeks from the day of its intake. In case bleeding does not happen by 3 weeks, you need to take urine pregnancy test along with ultrasound scan of the abdomen and seek medical attention promptly. There is a failure rate of 10 to 15% with the use of such pills. Hope the information provided would be helpful. All the best.