how much days she have to wait for her periods?

Hi,
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If she has regular menstrual cycles, then she should have got her periods within 10 days of expected period dates. Emergency contraceptives contain high dosages of hormones and can disrupt the normal hormonal and period pattern. Wait and watch for her periods/withdrawal bleeding. Look out for development of any new symptoms if pregnancy is suspected. She should visit her gynecologist for further evaluation and assistance if she has not got her periods within 10 days of expected period dates, or if she gets abnormal bleeding. If pregnancy gets ruled out and if you are not ready for pregnancy, but intend to remain sexually active, you should consider getting her started on suitable regular birth control measures to be protected (after her periods). She should be regular with birth control use as instructed. If pregnancy gets ruled out, further evaluation would be done to look for the underlying cause for the missed periods. Treatment as appropriate (based on examination findings and investigations results) would be started to help her get periods and regulate her periods. She should be in regular monitoring and follow-up with her treating doctor/gynecologist and report any new/abnormal symptoms immediately.
Take care.