Hi, Thanks for writing in HCM. I understand your concern. Unwanted 72 is an emergency contraceptive pill that needs to be taken within 72 hours of having unprotected intercourse. It will cause withdrawal bleeding in the form of periods within 3 weeks from the day you have taken the pill. This would confirm that the pregnancy has been prevented from happening. Since it is hormonal preparation, the next few cycles may be early or late as the body needs to get adjusted to its normal levels. Hence, you may wait for next couple of cycles to reach normalcy. In case it doesn t, kindly seek medical help. Hope the information provided would be useful. All the best.