which is a emergency contraceptive pill
can protect from pregnancy
as you have taken within 40 hours of intercourse,
they are having side effects like menstrual irregularities, spotting etc, they can prepone and postpone the periods depending on the time when they have taken,
if you do not get periods on expected date, you once check for pregnancy as the tablets are having 1% failure rate.
as frequent taking of pills can affect menstrual cycles,
so better to shift to regular method of contraception