Hi and welcome to HCM If you have taken the emergency contraceptive within 48-72 hours of the unprotected sexual intercourse, it should work in preventing pregnancy (provided you were not sexually active without protection after taking it). Even if ejaculation has occurred inside vagina, emergency pills can prevent pregnancy. Since the pills contain high doses of hormones, these can disrupt the normal hormonal and period pattern causing period/bleeding abnormalities and appearance of new symptoms. Wait and watch for your next periods which can be delayed. Look out for development of any other new symptoms If pregnancy is suspected, or if you miss your periods, or if you have abnormal periods, consider visiting your doctor/gynecologist at the earliest for thorough examination (to confirm pregnancy related changes/signs in body) and blood/serum HCG level test (to confirm/rule out pregnancy accurately). If pregnancy gets ruled out and if you are not ready for pregnancy, but intend to remain sexually active, you should consider getting started on suitable regular birth control measures to be protected (after periods). Be regular with birth control use as instructed. Avoid having unprotected sexual contact if you are not ready for pregnancy. Regards Dr Santosh