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The emergency contraceptive pills work if taken within 48-72 hours of unprotected intercourse. Withdrawal bleed usually occurs within 5-7 days of taking ECP (which may not occur if taken close to periods). Since the emergency contraceptives contain high dosages of hormones, these can cause period pattern abnormalities and delayed 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.
Take care.