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You had contact on 23rd day of your period, which is safe period, provided your periods are regular. If the periods are not regular, there is a possibility of becoming pregnant.
If you still feel you could get pregnant take 2 tablets of ECEE2, immediately and 2 Tablets after 12 hours. If vomiting
occurs within 3 hours of taking the tablets, then again you have to take two tablets, as the previously taken tablets will have been lost in the vomiting.