i had unwanted 72 tell when my periods will start?

Hi,
Welcome to ehealthforum,
Taking ECP within 24-48 hours of unprotected intercourse helps in preventing pregnancy (provided you were not sexually active after taking it). Withdrawal bleeding occurs within 5-7 days of taking the pill indicating that it has worked (which may not occur if you have taken ECP close to periods). Since these pills contain high dosages of hormones, these affect the hormonal and period pattern causing delay in next periods. Wait and watch for your periods which could be delayed due to the emergency contraceptive use. Visit your doctor/gynecologist for further evaluation if periods do not start within 10 days or if you suspect chances of pregnancy, or if you develop any other new symptoms. If pregnancy gets ruled out, and if you are not ready for pregnancy, but intend to remain sexually active, you should consider visiting your gynecologist to get started on suitable regular birth control measures to be protected (after your periods). Be regular with birth control use as instructed. Avoid having unprotected sexual contact if you are not ready for pregnancy. Avoid repeat use of ECP.
Take care.